PNL-7105
Vol. 1
UC-95
ARCHITECT'S AND ENGINEER'S GUIDE TO ENERGY
CONSERVATION IN EXISTING BUILDINGS
Volume 1 - Energy Use Assessment
and Simulation Methods
February 1990
Prepared for
the U.S. Department of Energy
under Contract DE-AC06-76RLO 1830
Pacific Northwest Laboratory
Richland, Washington 99352
SUMMARY
This first volume of the Architect's and Engineer's
Guide to Energy Conservation in Existing Buildings serves as a
resource for federal energy managers to assist them in
understanding and undertaking energy conservation projects. This
volume is a general overview or preview on energy conservation in
general, while the second volume deals with 118 specific energy
conservation opportunities (ECOs).
Chapter 1.0 is an introduction to the Federal Energy
Management Program (FEMP), as well as an overview of this twovolume guide. Chapter 2.0 presents background information on
characteristics of the federal buildings sector and reviews
pertinent federal legislation concerning energy conservation.
Chapter 3.0 provides guidance on how to assess energy use in
federal facilities. Included in Chapter 3.0 is a discussion of
analysis of utility bills, screening for energy conservation
opportunities, analysis of promising opportunities, and
identification of supplemental metering needs. With the increasing
use of computers, especially personal computers, many building simulations or models are now available to aid energy managers or
architects/engineers in analyzing ECOs. Chapter 4.0 discusses the
evolution of these diverse computer simulation models, the most
common calculational methods and approximations used by the models,
the typical data input needed to use these models effectively, how
to use the models for ECO analysis, and how to interpret the model
results. The last section of Chapter 4.0 discusses some of the
limitations associated with using computer models in ECO analysis.
The two-volume guide is based on research performed by
Pacific Northwest Laboratory1 and The Fleming Group for the Federal
Energy Management Program within the Office of Conservation.
1
Pacific Northwest Laboratory is operated for the U.S.
Department of Energy by Battelle Memorial Institute.
ACKNOWLEDGMENTS
This update to the Architect's and Engineer's Guide to
Energy Conservation in Existing Buildings was prepared by Pacific
Northwest Laboratory (PNL) and The Fleming Group (TFG) with funding
from the Federal Energy Management Program. Principal authors are
Richard Mazzucchi and Steve Weakley of PNL. Major contributions
were made by Dennis Landsburg and Jim Fireovid of TFG and Bobi
Garrett and Judy Danko of PNL.
The authors wish to thank K. Dean DeVine, PE of the
Federal Energy Management Program, whose direction and efforts were
instrumental in completing this work, and Richard W. Brancato,
Director of the Federal Energy Management Program for his
continuing support. The authors also wish to express their
appreciation to the countless energy professionals whose work and
careful thinking have revealed the significance of energy
conservation in existing buildings.
CONTENTS
SUMMARY
. . . . . .
iii
ACKNOWLEDGMENTS
..... v
1.0
2.0
3.0
INTRODUCTION................................................. 1.1
1.1 THE FEDERAL ENERGY MANAGEMENT PROGRAM................... 1.1
1.2
OBJECTIVES OF THE ARCHITECT'S AND ENGINEER'S GUIDE ..... 1.2
1.3
OVERVIEW OF GUIDE ...................................... 1.2
BACKGROUND .................................................. 2.1
2.1
FEDERAL BUILDING SECTOR................................. 2.1
2.2
FEDERAL LAWS APPLICABLE TO FEDERAL BUILDING ENERGY
IMPROVEMENTS ................................. 2.4
2.2.1
Energy Performance Targets....................... 2.4
2.2.2
Energy-Efficiency Standards...................... 2.5
2.2.3
Shared Energy Savings Contracting................ 2.5
2.2.4
Life-Cycle Costing............................... 2.6
ENERGY USE ASSESSMENT........................................ 3.1
3.1 TEAMWORK - THE KEY TO PROGRAM SUCCESS.............. 3.1
3.2
ANALYSIS OF UTILITY BILLING DATA................... 3.2
3.3
SCREENING FOR ENERGY-EFFICIENCY OPPORTUNITIES...... 3.2
3.3.1
Types of Energy Audits for Buildings........ 3.3
3.3.2
Energy Conservation Opportunities........... 3.5
3.4
ANALYSIS OF ENERGY CONSERVATION OPPORTUNITIES...... 3.8
3.5
SELECTION OF SUPPLEMENTAL METERING POINTS.......... 3.10
4.0
SIMULATION METHODS........................................... 4.1
4.1
4.2
4.3
4.4
4.5
BUILDING ENERGY USE SIMULATION MODELS.............. 4.2
4.1.1 Types of Building Energy Simulations........ 4.2
4.1.2
Life Cycle Costing.......................... 4.4
4.1.3
Types of Calculations....................... 4.4
4.1.4
Development of Energy Simulations........... 4.5
4.1.5
Main Frame Simulation Programs.............. 4.6
4.1.6
PC-Based Simulations........................ 4.7
CALCULATION TECHNIQUES............................. 4.8
4.2.1 Variable Base Degree Day Method............. 4.8
4.2.2
Modified Bin Method......................... 4.8
4.2.3
Typical Day Method.......................... 4.9
4.2.4
Hourly Method............................... 4.9
4.2.5
Network Methods............................. 4.10
NATURE OF INPUTS REQUIRED.......................... 4.10
4.3.1 Type of Data Required and Organization...... 4.10
4.3.2
Level of Detail Considerations.............. 4.14
4.3.3
Building Simulation Input Formats........... 4.16
4.3.4
Example of Simulation Model Inputs.......... 4.17
SINGLE SIMULATION ................................. 4.19
4.4.1 Running the Baseline Case................... 4.19
4.4.2
Changing Inputs for ECOs.................... 4.20
4.4.3
Comparing Output for Effect of ECOs......... 4.22
PARAMETRIC ANALYSES................................ 4.22
4.6
4.5.1
Evaluating Parametric Combinations of ECO
Variables............................. 4.22
4.5.2
Variables That Can Be Changed.............. 4.22
4.5.3
Limitations on Variables................... 4.23
INTERPRETING RESULTS.............................. 4.23
4.6.1 Changes in Energy Uses..................... 4.23
4.6.2
4.7
4.8
5.0
Calculating Payback and Using Life Cycle
Costing............................... 4.29
LIMITATIONS OF SIMULATIONS................... 4.30
4.7.1 General Limitations................... 4.30
4.7.2
Loads Limitations..................... 4.30
4.7.3
Systems Limitations................... 4.31
4.7.4
Plant Limitations..................... 4.32
THE FUTURE OF ENERGY SIMULATIONS............. 4.32
REFERENCES.................................................. 5.1
APPENDIX A - INFORMATION TO BE GATHERED DURING AUDITS............ A.1
APPENDIX B - SIMULATION MODEL INPUTS FOR ASEAM VERSION 2.1....... B.1
APPENDIX C - PARAMETRIC INPUT AND OUTPUT VARIABLE LIST FOR
ASEAM VERSION 2.1................................... C.1
FIGURES
4.1
Graphical System Display............................ 4.29
TABLES
2.1
Percentage of Building Space by Predominant Usage....... 2.1
2.2
Federal Energy Use in Buildings and Facilities.......... 2.2
2.3
Energy Consumption by Principal Building Activity,1986.. 2.3
2.4
Energy Intensity by Region, 1986........................ 2.3
4.1
Applicability of Simulation Methods to ECO Analyses..... 4.21
4.2
Sample ASEAM2 Building End Use Report................... 4.24
4.3
Sample ASEAM2 Loads Report.............................. 4.25
4.4
Sample ASEAM2 Systems Output Report..................... 4.26
4.5
Sample of Tabular ASEAM Report.......................... 4.27
4.6
Sample of ASEAM2 Calculation............................. 4.28
1.0
INTRODUCTION
The federal government is the nation's single largest energy
consumer, using 1.9 quads of energy annually at more than 8000 locations
worldwide.1 Both the magnitude of the energy consumed and the potential for
energy savings have been the basis for legislative and administrative
initiatives and programs for energy conservation in the federal buildings
sector. Based on an estimated 1% replacement rate from 1990 forward, new
energy-efficient building stock will contribute only about 5% to building
energy savings by the year 2000. Thus, savings must be realized largely
through retrofits to existing buildings if the federal government is to
maximize its energy efficiency (DOE 1983).
1.1
THE FEDERAL ENERGY MANAGEMENT PROGRAM
The Federal Energy Management Program (FEMP) supports the mission
of the U.S. Department of Energy (DOE) to achieve effective management of the
energy functions of the federal government by providing assistance to federal
agencies in planning and implementing programs that will improve the
efficiency and fuel flexibility of the federal infrastructure (facilities,
operations, and transportation systems).
Since its establishment in 1973, FEMP has evolved and expanded in
recognition of the complexity of managing energy use in the federal sector.
Better energy management programs in many federal facilities have helped to
reduce use and expenditures for energy. Cumulative budget savings for energy
since 1977 are estimated to be over $6 billion, a significant reduction in
federal spending (DOE 1988). While important strides have been made toward
energy efficiency and fuel flexibility, the potential for additional savings
in federal facilities and operations remains high.
At the core of the program is the recognition that energy
consumption is inextricably linked to the life cycle of the physical
infrastructure and that a holistic approach to energy management is needed.
The need to rebuild the national infrastructure will be a significant problem
facing the United States government during the remainder of this century and
beyond. Many construction and rehabilitation decisions will be made over the
next several years. These decisions will have energy implications for the
next 40 to 50 years.
1
U.S. Department of Energy. 1989 (draft). Annual
Report on Federal Government Energy Management Fiscal
Year 1988. Assistant Secretary, Conservation and
Renewable Energy, Washington, D.C.
1.1
1.2
OBJECTIVES OF THE ARCHITECT'S AND ENGINEER'S GUIDE
This updated Architect's and Engineer's Guide to Energy
Conservation in Existing Buildings (A&E guide) has been prepared by FEMP to
provide federal energy managers, facility energy coordinators, contractors,
and other decision makers with current information on opportunities for
improving energy efficiency and on analysis methods.
As nonrenewable energy sources are depleted and energy demands and
costs rise, the potential for energy savings escalates. At the same time, the
risks associated with capital investments in efficiency improvements are
reduced, and the number of energy-saving options are increased by a better
understanding of building energy use and a growing number of conservation
technologies and analysis techniques.
Current concern about international competitiveness, global warming
as a result of fossil fuel combustion, nuclear power production and waste disposal, and the relatively high cost of alternative energy forms further support aggressive action to increase energy efficiency in the United States.
The advent of low-cost desktop computers and data acquisition
systems has made it possible for architects and engineers to model building
energy use, calibrate the models to metered data, and then use the models to
investigate potential energy conservation opportunities. For this reason,
FEMP has supported the development of a public domain program, ASEAM (A
Simplified Energy Analysis Method) for simulating energy use in buildings.
This A&E guide provides examples of how ASEAM can be used to
evaluate many energy conservation opportunities (ECOs) by taking into account
the interactions of energy end-uses, climate and building use. Anyone who
uses this A&E guide will surely benefit from courses offered by the General
Services Administration on the use of the ASEAM program.
The A&E guide explains how energy is used in buildings, how ECOs work,
and how particular ECOs can be evaluated; thus, the guide should be useful to a very
wide audience. However, it is important to understand that the results of any energy
analysis are only as good as the input data, the analysis tools, and the analyst's
knowledge.
1.3
OVERVIEW OF GUIDE
This A&E guide is in two volumes. Volume 1 discusses the characteristics of energy use in the federal buildings sector, federal legislation pertinent to
energy conservation, energy use assessment of facilities, and modeling or simulation
methods used to analyze ECOs. Volume 2 presents the following specific information
on 118 ECOs: implementation of each ECO, information required to analyze each ECO,
and use of a personal computer model (ASEAM) to analyze each ECO. These 118 ECOs
fall into the following eight categories: building equipment operation, building
1.2
envelope, HVAC equipment systems, HVAC distribution systems, water heating systems,
lighting systems, power systems, and miscellaneous ECOs dealing with control systems
and heat recovery.
1.3
2.0
BACKGROUND
This section provides a brief overview of characteristics of the federal
buildings sector and a review of the legislative authorities that guide the
energy improvement activities within federal buildings.
2.1
FEDERAL BUILDING SECTOR
The federal government owns or leases more than 500,000 buildings
and facilities, totalling more than 3.3 billion square feet of floor space in
the United States.1 The government owns approximately 93% of this square footage and leases the remaining 7%. The largest single use of federally owned and
leased buildings is housing, which accounts for over 24% of the total use.
Storage, office space, and service-related space are the next largest uses,
combining to total 56% of the building space. The remaining 20% of floorspace
is used for other needs as delineated in Table 2.1 (GSA 1988a,b).
The largest building manager and consumer of energy within the
federal government is the Department of Defense (DOD). Approximately three
quarters of the energy used for federal buildings is used by the DOD. Most of
the remaining quarter is used by the following ten civilian agencies: DOE, Veterans Administration (VA), United States Postal Service (USPS), General Service
Administration (GSA), National Aeronautics and Space Administration (NASA),
Department of Transportation (DOT), Health and Human Services (HHS), Department
of the Interior (DOI), Department of Justice (DOJ) and United States Department
of Agriculture (USDA). (See Table 2.2.)(a)
TABLE 2.1.
Percentage of Building Space by Predominant Usage
Type
Housing
Storage
Office
Services
Hospitals
Research and Development
Schools
Prisons and Other Institutions
Industrial
Miscellaneous
1
Area
in Percent
24
17
22
17
1
4
5
3
4
3
U.S. Department of Energy. 1989 (draft). Annual Report on
Federal Government Energy Management Fiscal Year 1988. Assistant
Secretary, Conservation and Renewable Energy, Washington, D.C.
2.11
TABLE 2.2.
Federal Energy Use in Buildings and Facilities
(For Fiscal Year 1988)
GSF(
Agency
a
)
x 103
Btu x 109
Btu/GSF(
Department of Defense
2,525,897.0
546,449.1
216,339
Department of Energy
75,892.9
56,601.2
745,804
U.S. Postal Service
203,668.0
43,801.4
215,063
Veterans Administration
131,120.0
43,785.6
333,936
General Services Administration
162,047.4
30,314.1
187,070
35,737.0
23,804.8
666,110
Department of Transportation
38,424.0
16,460.9
428,401
Department of Health and Human Services
21,575.0
11,930.4
552,974
Department of Justice
25,818.6
10,298.7
398,885
Department of Agriculture
23,700.0
7,589.5
320,230
Department of Interior
54,525.3
7,289.2
133,684
Department of Labor
16,100.0
4,264.2
264,858
Treasury Department
10,119.3
6,601.8
652,394
Department of Commerce
5,663.1
2,683.6
473,883
Tennessee Valley Authority
5,569.2
1,500.1
269,363
Environmental Protection Agency
1,454.9
970.6
667,125
Panama Canal Commission
3,040.0
927.3
305,041
National Science Foundation
901.0
537.1
596,150
Federal Communications Commission
121.0
35.2
290,736
3,341,373.7
815,844.8
244,164
a
National Aeronautics and Space
Administration
TOTALS
(a)
Gross square foot.
Spending approximately $3.7 billion for building energy in 1988,
the federal government used 0.8158 quadrillion Btu (quads) of energy for
building lighting, heating, ventilation, air conditioning, other standard
building services and some process operations.2 Electricity constituted 62.3%
2
U.S. Department of Energy. 1989 (draft). Annual Report on
Federal Government Energy Management Fiscal Year 1988. Assistant
Secretary, Conservation and Renewable Energy, Washington, D.C.
2.2 NEX
)
of total federal building energy consumption; 16.6% was accounted for by natural
gas; and 11.3% was accounted for by fuel oil. Small amounts of coal, purchased
steam, liquified petroleum gas and propane, and "others" (consisting mainly of
chilled water and renewable energy) accounted for the remaining 9.8% (EIA 1988).
Although end-use consumption data are not available specifically
for federal buildings, commercial buildings data obtained by the DOE Energy
Information Administration (EIA) in the Nonresidential Buildings Energy Consumption Survey can be generalized to estimate energy use for similar federal
buildings such as offices, health care facilities, schools, service and storage
buildings. The average energy consumption by building type for the calendar
year 1986 is shown in Table 2.3 (EIA 1989). The building types with the highest
energy consumption include offices and mercantile/service buildings. Health
care buildings have the highest consumption per square foot (216,900 Btu/ft2 ).
Building size seems to be negatively associated with consumption per square
foot. For the most part, as building size increases, consumption per square
foot decreases (186,000 Btu/ft2 for buildings with 1,000 square feet or less, to
about 90,000 Btu/ft2 for buildings with over 50,000 square feet) (EIA 1989).
Table 2.4 (EIA 1989) highlights regional differences in energy
consumption that can be attributed primarily to climate, but also to the average
size of the buildings in the area and other uncontrollable factors.
Based on 1985 data, overall functional use of energy in the
commercial building category is as follows:
@
55% for space conditioning, two-thirds of
which was used for heating, and the remainder
for air-conditioning and ventilation
TABLE 2.3.
Energy Consumption by Principal Building Activity, 1986
Principal Activity
Within Building
Energy Consumed/ft2
(in Btu)
Assembly
Educational
Food Sales
Food Service
Health Care
Lodging
Mercantile/Services
Offices
Public Order and Safety
Warehouse
Other
Vacant
TABLE 2.4.
Energy Intensity by Region, 1986
2.3 NEXTRECORD
54,900
87,100
211,600
202,600
216,900
111,600
78,400
106,000
126,700
54,500
99,500
44,000
Region Building
Located in
Energy Consumed/ft2
(in Btu)
Northeast
North Central
South
West
@
25% for lighting
@
5% for hot water heating
@
15% for miscellaneous use.
90,900
101,900
78,600
84,600
These percentages vary among commercial building types and climatic
regions (DOE 1989). Of the various end-uses, space conditioning is the most
prevalent. As of 1986, 63.2% of all commercial buildings were totally heated,
25.5% were partially heated, and 11.3% were unheated. Additionally, 69.4% of
all commercial buildings had air-conditioning (EIA 1988).
Housing is the most common use of federal buildings, and is also
the predominant energy user. Generalizations about the way that energy is used
within this segment can be made using the available consumption data for nonfederal single and multifamily dwellings. In 1985, 60.8% of the energy consumed
in the residential sector was used for space conditioning (56.8% for heating,
and 4% for air-conditioning). Other residential energy uses include hot water
heating (18.0%) and appliance usage (21.2%) (EIA 1987).
2.2
FEDERAL LAWS APPLICABLE TO FEDERAL BUILDING ENERGY IMPROVEMENTS
In recognition of the magnitude of the energy-savings potential in
the federal government, Congress has enacted a number of laws since 1973 that
have served to define the direction of federal energy improvement activities.
This section provides a brief overview of the pertinent aspects of this
legislation.
2.2.1
Energy Performance Targets
The Federal Energy Management Improvement Act of 1988 established a
fiscal year 1995 energy performance goal for federal buildings. The act states
that each agency shall apply energy conservation measures and improve the design
of new construction such that the energy consumption per gross square foot of
its buildings in use in fiscal year 1995 is at least 10% less than the energy
consumption per gross square foot in 1985. To achieve this goal and identify
high priority projects, each agency is required to
@
prepare or update a plan for achieving the 10%
reduction in energy use
2.4 NEXTRECORD
@
perform energy surveys of its facilities to
the extent necessary
@
apply life-cycle costing (LCC) methods in the
design of new buildings and in the selection
of conservation measures for existing
buildings.
2.2.2
Energy-Efficiency Standards
The Omnibus Reconciliation Act of 1981 established the Building
Standards in Federal Facilities Program, which required that energy-efficiency
standards for federal buildings be developed and disseminated to federal
agencies.
The current energy-efficiency standard for existing federal
buildings is the DOE Standard, which was first issued in November 1988. This
standard, which is voluntary for the private sector, is mandatory for federal
buildings. The DOE Standard is a slightly modified version of the American
Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)/
Illuminating Engineering Society (IES) Standard 90.1. This standard was
developed for new buildings, but it is applicable as a cost-effective method for
retrofitting existing buildings when it is coupled with DOE's LCC procedures.
The standards are expected to be used in the following way for any
major building retrofit project. First, the building would be audited to
compare the energy efficiency of its walls, roof, HVAC equipment, and other
components with those specified for that climate in the DOE Standard. Second,
the retrofit measures necessary to bring the building close to the DOE Standard
would be subject to the net benefit analysis of the LCC procedure to determine
the applicability of each energy-saving measure. The measures would then be
prioritized according to the savings-to-investment ratio (SIR) calculation of
the LCC procedure. Third, a retrofit plan would be developed to include those
measures that are cost-effective under the DOE LCC procedures.
2.2.3
Shared Energy Savings Contracting
Shared-energy savings (SES) is a contracting method whereby the
contractor incurs "costs of implementing energy savings measures, including at
least the costs (if any) of providing energy audits, acquiring and installing
equipment, and training personnel, in exchange for a share of any energy savings
directly resulting from implementation of such measures during the term of the
contract."
Legislative authority for federal agencies to enter into multi-year
shared-energy savings contracts was granted on April 7, 1986, when President
Reagan signed the Consolidated Omnibus Budget Reconciliation Act of 1985 (P.L.
99-272). In October 1988, the Federal Energy Management Improvement Act was
enacted. One provision of this act that has the greatest potential impact on
federal shared-energy savings is that each agency is required to establish a
program of incentives for conserving and otherwise making more efficient use of
2.5 NEXTRECORD
energy as a result of entering into SES contracts. The heart of this program is
that the head of the agency can utilize any savings from the annual energy
expenses (e.g., the difference between the amount budgeted and the amount spent)
to undertake additional energy-conservation measures.
The following are two significant advantages of SES contracting in
the federal environment:
@
No up-front funding is required. By law, all
payments to the contractor are made from the
agency's annual building operating (utility)
budget. Thus, the waiting time and
uncertainty surrounding funding for needed
capital improvements are greatly reduced.
@
Because the contractor provides all of the
expertise and the funding, the technical and
economic risk to the government is reduced.
Because the concept of SES contracting is new to the federal
government and runs contrary to many conventional procurement practices, there
can be extensive learning curve time and expense for the first SES projects
implemented by an agency. Because of the time and expense involved with first
projects, it is critical that agencies select candidate projects that have the
highest probability for these pilot SES contracts to succeed.
2.2.4
Life-Cycle Costing
The LCC methodology issued in December 1980 (Ruegg 1980) is used as
the primary criterion for allocating funding for energy conservation retrofit
measures to existing federal buildings. This method of economic evaluation
takes into account all relevant costs (design, system, component, material, and
practice) of a building over a given period of time, adjusting for differences
in the timing of these costs.
The above data on cost and savings from a project can be combined
in a number of different ways to evaluate its economic performance. For evaluating potential FEMP projects, one or more of the following modes of analysis
are required:
@
total life-cycle costs (TLCC) - TLCC is the
sum of all significant dollar costs of a
project discounted to present value.
@
net life-cycle savings (NS) - NS is the
decrease in the TLCC of a building or building
system that is attributable to an energy
conservation or renewable energy project.
@
savings-to-investment ratio (SIR) - The SIR is
a numerical ratio. The numerator is the
2.6 NEXTRECORD
reduction in energy costs, net of increased
non-fuel operation and maintenance costs; the
denominator is the increase in investment
cost, minus increased salvage values, plus
increased replacement costs.
@
payback period (PB) - The PB is the elapsed
time between the initial investment and the
time at which cumulative savings in energy
costs, net of other future costs associated
with the project, are just sufficient to
offset the initial investment costs.
The four modes of analyses are not equally suitable for choosing
among alternative new building designs, for designing and sizing projects for
new and existing buildings, or for ranking available retrofit projects in terms
of their relative cost-effectiveness. For instance, TLCC is generally best for
choosing among alternative designs for a new building, while SIR is best for
ranking retrofit projects according to their effectiveness.
Based on these analyses, priority is given to projects with the
highest LCC savings-to-investment ratio. The NECPA requires that changes in
operations and maintenance procedures have priority over measures requiring
substantial structural modification or installation of equipment. Energyefficiency considerations are not to adversely impact the mission responsibilities of the agencies (DOE 1983).
2.7 NEXTRECORD
3.0
ENERGY USE ASSESSMENT
Assessing the efficiency of energy use is central to energy
management programs. Such an assessment entails establishing an energy
management team, understanding present energy-using systems and conservation
options, and implementing methods to track the effectiveness of energy use. The
most successful energy management programs continuously monitor energy use and
track progress toward realistic efficiency goals. In this way, the effects of
investments in efficiency improvement are determined so that the program can
build upon successes while learning from occasional failures.
This chapter provides general guidance for starting or improving an
existing energy management program. Several common activities have critical
bearing on program success. These ingredients include configuring an effective
energy management committee, analyzing historical utility billing records,
screening for energy efficiency opportunities, analyzing promising measures, and
identifying supplemental metering needs.
When this guidance is combined with the detailed information in
Volume 2 of this A&E guide regarding assessment of ECOs, the facility energy
manager and consultants will have a sound framework for conducting the energy
management program.
3.1
TEAMWORK - THE KEY TO PROGRAM SUCCESS
Achieving optimal energy use efficiency requires the coordinated
action of many individuals working toward a set of common objectives. Not only
must energy-using systems be designed with efficiency in mind, but the equipment
must be properly operated and maintained over its useful life. The system
designs should account for the overall impacts on the utility suppliers and the
environment, and energy conservation measures should not jeopardize amenity
levels, productivity, or mission readiness.
The energy management program team may include the following:
@
facility energy management staff - to include
the energy coordinator, the operations and
maintenance foreman, and the utility clerk
@
servicing utility representatives - to include
the principal fuel suppliers
@
facility tenant representatives - to include
the principal building occupants and users
@
energy specialists - to include any consultants
or contractors involved with designing or
assessing facility energy use.
3.1 NEXTRECORD
This team should meet at least once every six months to review
energy-use levels and program efforts. More frequent meetings and communication
among subsets of this team should be conducted on an as-needed basis to resolve
problems and develop new program initiatives.
One of the first tasks of the energy management team is to determine
the present energy end-uses and to establish achievable goals for improving
energy efficiency. These activities necessitate a careful accounting of energy
flows and a reasonably comprehensive understanding of the characteristics of
energy-using systems. The amount of measured data available for facilities is
often limited, so initial program investments should be focused on overcoming
these limitations by assembling the available data, identifying information
gaps, and carrying out energy-use surveys and metering projects.
3.2
ANALYSIS OF UTILITY BILLING DATA
assessment.
In most cases utility billing data are the best place to begin the
The following information should be assembled:
@
prior billing records for the past three to
five years including the quantities of energy
consumed, the meter reading dates, and the
utility rate structures
@
meteorological summaries for the facility
indicating the daily minimum and maximum
temperatures
@
salient characteristics and documents
pertaining to the facility, such as the square
footage of the buildings and construction documents; history of additions, demolitions, or
other changes in the building stock or tenancy;
central plant capacities and operation logs;
and prior energy studies or conservation
initiatives.
These data should be assembled and summarized in an electronic
spreadsheet for subsequent analysis. As the sensitivity of energy use levels to
weather and environmental parameters is explored, the billing records can be
normalized for changes in climate. This is accomplished by matching the billing
records to the exterior temperature conditions during the same period and
conducting statistical regressions to explain historical variations in energy
use. Once these baseline conditions are established, the aggregate performance
of energy conservation initiatives can often be determined and energy cause and
effect relationships can be more fully understood.
3.3
SCREENING FOR ENERGY-EFFICIENCY OPPORTUNITIES
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The first task to be undertaken when screening a facility (or
facilities) for energy-efficiency improvements is to assemble accurate
information on the facility's characteristics and on conservation opportunities.
The three types of audits that should be or could be undertaken are discussed in
this section. The information to be gathered in each audit and analysis methods
using the data will be detailed. Some of the more common ECOs will then be
highlighted. An example of an ECO analysis will be shown using a sample
building and a PC-based simulation model. Results of examining the effects of a
wide variety of ECOs on the example building will be presented.
3.3.1
Types of Energy Audits for Buildings
Most energy audits fall into three categories or types:
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preliminary or walk-through audits
building/system audits
end-use/equipment audits.
These are discussed in detail below.
Preliminary or Walk-Through Audit
The information to be gathered during the preliminary audit can be
divided into four categories: overall facility information, information on
major energy-using systems/equipment, types of systems/equipment contained in
the building, and energy billing data. A complete list of information to be
obtained in the preliminary audit is included in Appendix A, Table A.1.
Of particular importance are the billing data, which are used to
calculate the Energy Utilization Index (EUI), in Btu/ft2. These data can be
compared with other facilities under study to allow the focus to fall on the
poorest performers in the group. Also, the EUI can be compared to EUIs for
functionally similar buildings, i.e., offices, warehouses, etc. The EUIs for
one building can be compared over time to note any significant changes.
Conducting a walk-through audit of the building will allow the
analyst to identify functional areas or zones of the building that will be
useful for the next audit step. A zone consists of a portion of the building
that shares common features such as
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operating schedule
thermostat setpoints
similar loads (e.g., lighting watts/ft2)
type of HVAC system
outside wall/roof exposure.
If possible, blueprints of architectural, electrical, and mechanical systems
should be used for zoning. Ensure that all updates to the systems have been
noted on the blueprints.
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Also on the walk-through audit, a description and location of all
major energy-using systems should be obtained, including HVAC equipment,
lighting systems, and control equipment. Any other major uses of energy in the
building, such as computers, laundry, or food services, should also be noted.
Additionally, the fuel and energy usage of the equipment should be noted, if
possible.
Building/Systems Audit
After gathering preliminary audit data, decide whether or not to
proceed to the next audit step: the building audit. While the preliminary
audit may be conducted by the building manager, the building audit may be more
cost-effectively done by a professional audit company. In many areas of the
country, the local utility may offer a free energy audit that includes a list of
potential ECOs. The information gathered during the building audit will be used
to model the energy use of the building, as well as to identify ECOs. The model
used should be able to show the effect of implementing various ECOs.
A list of the information that should be gathered during a building
audit is included as Table A.2 in Appendix A. This information is divided into
the following five categories or types of data:
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building envelope or shell
heating, ventilating, and air conditioning
lighting and electrical systems
central plant systems
weather.
End-Use/Equipment Audit
The final audit type, the end-use/equipment audit, should be
undertaken only if the building audit shows a need for further information or
that a particular ECO may be warranted. For example, a complete boiler analysis
may be identified as a need in the building audit. In most cases, a
professional boiler expert or engineer will need to perform this audit.
Similarly, a professional HVAC engineer will be needed to evaluate the
performance of the cooling plant components. Another method of gathering more
detailed data for some systems (e.g., lighting and electrical) is to meter or
monitor the end-uses of energy in the building. This allows the total energy
use in the building to be disaggregated to a significant degree. This last
audit step is very expensive and time-consuming and is usually only undertaken
if it seems likely that significant savings will result from the identification
of ECOs.
3.3.2
Energy Conservation Opportunities (ECOs)
The most common ECOs found in existing commercial buildings fall
into the following nine categories:
1.
building equipment operation
2.
building envelope
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3.
HVAC systems
4.
HVAC distribution systems
5.
water heating systems
6.
lighting systems
7.
power systems
8.
energy management control systems
9.
heat recovery/reclaim systems.
An ECO may be realized either by implementing operation and maintenance (O&M)
measures or by incorporating available technologies. Each of these energy
conservation areas is briefly described below. Volume 2 of this document
provides a detailed listing and discussion of ECOs in each of these areas.
Building Equipment Operation
An enormous amount of energy is wasted because building equipment is
operated improperly and unnecessarily. When the building is not occupied, the
building systems should be turned off or their operation reduced to a minimum.
Depending on building operations, the following systems' operating hours can be
curtailed during slack time: HVAC systems, water heating systems, lighting
systems, escalators and elevators, and other equipment and machinery. Care must
be taken to ensure that the reduction in hours has no adverse impact on building
operations and systems.
Building Envelope
The amount of heat (sensible and latent) supplied to or extracted
from the indoors in order to maintain a comfortable indoor environment is
directly proportional to the difference in temperature and humidity between
indoors and outdoors. Consequently, one should lower the heating and raise the
cooling temperature setpoints and/or lower the humidification setpoints and
raise the dehumidification setpoints to minimize the space conditioning requirements. Another ECO is to set the heating setpoints back when the building is
not ocupied. Care must be taken to ensure that the slight discomfort of the
occupants does not reduce their productivity.
Energy is saved when the heat exchange between the building and the
outside environment is reduced and/or solar and internal heat gains are controlled. The primary way to reduce heat conduction through ceilings/roofs,
walls, and floors is by adding insulation. Another method is to install vapor
barriers in ceilings/roofs and walls. To control or reduce solar heat gains
through the roof or glazing areas, a reflective surface or film can be used.
For glazing areas, the installation of interior or exterior shading will also
help control solar heat gain. The installation of storm windows or multipleglazed windows will also reduce heat conduction and long-wave radiation through
glazing areas.
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Infiltration is the unintended entry of unconditioned air into the
building through doors, windows, and other openings in the building envelope.
Infiltration can result in large increases in heating and cooling loads. Many
infiltration control strategies are inexpensive and relatively simple to
implement. Energy can be saved by sealing vertical shafts and stairways,
caulking and weatherstripping doors and windows, or installing vestibules and
revolving doors.
HVAC Systems
The HVAC systems in the building are made up of energy conversion
equipment, which transforms electrical or chemical energy to thermal energy, and
distribution and ventilation systems, which transport the thermal energy and
supply fresh outdoor air to the conditioned space. Energy may be saved in HVAC
systems by reducing ventilation requirements; improving the performance of space
conditioning equipment such as boilers, furnaces, chillers, air conditioners,
and heat pumps; using energy-efficient cooling systems; and reducing the
occurrence of reheating or recooling.
HVAC Distribution Systems
HVAC distribution systems transport the heating and cooling fluids
(generally air, water, or steam) from the central plants (chillers, boilers,
etc.) to the conditioned space. The system is made up of a network of pipes,
ducts, fans, pumps, grills, etc. Energy is required by the fans and pumps that
transport the working fluids. In addition, thermal energy is lost from the
distribution systems, reducing heating or cooling capacity. Consequently, ECOs
for distribution systems fall into two areas: reduction of energy required to
transport fluids, and reduction of energy losses during transport.
Water Heating Systems
In general, heating and distribution of hot water consumes less
energy than space conditioning and lighting. However, for some cases, such as
hospitals, restaurants, kitchens, and laundries, water heating amounts to substantial energy consumption. Water heating energy is conserved by reducing load
requirements, reducing distribution losses, and improving the efficiency of the
water heating systems.
Lighting System
Lighting accounts for a significant fraction of electrical energy
consumed in a building. Energy is saved and electric demand is reduced by
reducing illumination levels, improving lighting system efficiency, curtailing
operating hours, and using daylighting. Reduction of lighting energy can also
increase the energy use of building heating and decrease cooling system
consumption, since internal heat gains are reduced. However, this heat-of-light
is often a relatively expensive method of heating a building. If the building
cooling plant is to be replaced, implementation of lighting ECOs will reduce the
required plant size.
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Power Systems
The inefficient operation of power systems stems mainly from a low
power factor. Power factor correction is cost-effective when utility penalties
are imposed. Low power factors can be improved with power factor correction
devices and high-efficiency motors. Additional energy can be saved by installing energy-efficient transformers and replacing existing motors with smaller
and/or higher efficiency motors, or by installing variable-speed motor drives.
The peak power demand can be reduced by load-shedding, cogeneration,
or cool storage systems that produce cold water or ice during off-peak hours.
Load-shedding may also reduce the total power consumption, as well as the
demand. Cogeneration systems will increase the use of onsite energy, but can
also replace electricity consumption with less expensive fossil energy. Also,
the waste heat from the cogeneration equipment can meet thermal loads. Cool
storage systems shift the chiller demand to off-peak periods, reducing on-peak
demand.
Evaluation of these ECOs requires a determination of the building
demand profile. Several weeks of data in 15-minute intervals should be taken
with a recording meter. The measurements may have to be taken both in the
cooling and heating season. Most electric utilities will provide this service
at a nominal charge.
Energy Management Control Systems
Energy can be saved by automating the control of energy systems
through the use of energy management and control systems (EMCS). Rising energy
costs and decreasing prices for computers and microprocessors have encouraged
the use of EMCSs. An EMCS can efficiently control the heating, ventilating, air
conditioning, lighting, and other energy-consuming equipment in the building.
It selects optimum equipment operating times and setpoints as a function of
electrical demand, time, weather conditions, occupancy, and heating and cooling
requirements. The basic control principles for building energy conservation are
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operate equipment only when needed
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eliminate or minimize simultaneous heating and
cooling
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supply heating and cooling according to actual
needs
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supply heating and cooling from the most
efficient source.
About 100 companies manufacture EMCSs, and new technology is
continually being developed. Potential users should be thoroughly familiar with
currently available EMCSs.
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Heat Recovery/Reclaim Systems
Heat recovery is the reclamation and use of energy that is otherwise
rejected from the building. When applied properly, heat reclaim systems may be
used to reduce energy consumption, as well as peak power demand. The effectiveness of a heat reclaim system for energy conservation depends on the
quantity and temperature of the heat available for recovery, as well as the
application of the reclaimed heat.
3.4
ANALYSIS OF ENERGY CONSERVATION OPPORTUNITIES
All building energy consumption can be viewed conceptually as a rate
of use multiplied by time (energy = rate X time). The maximum rate is specified
or limited by parameter specifications of capacity or by intensity, such as wall
U value, lighting watts/ft2, or chiller tonnage. The rate over time is
specified by the operating schedule or weather variables. The type of parameter
and how it varies over time can be used to select the appropriate analysis
technique. For example, an external lighting system uses energy at a constant
rate, usually operates on a known schedule, and has no interaction with other
patterns of building energy consumption. Therefore, a change in installed kW
(rate) or operating schedule (time) can be calculated manually with precision.
For most ECOs, however, an accurate calculation is not that simple.
For example, the performance of heating and cooling systems is affected by
internal heat gains and weather variables, which vary in a complex fashion over
time. The efficiencies of the plant equipment and HVAC systems vary with
percentage of load. Therefore, using an energy model rather than manual
techniques offers the following accuracy improvements:
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Building parameters can be precisely scheduled.
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The impact of weather can be precisely
determined.
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Equipment performance can be specified at partload.
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Variable interactions, such as the effect of
internal lighting reductions on heating and
cooling loads, can be calculated.
Before personal computers were widely used, building energy analysts
had limited choices of calculation methods for evaluating ECOs. Typically, they
used manual calculation methods and nomographs. Those methods are simple and
require a relatively low level of effort from the user. However, those methods
are not as accurate and comprehensive as automated methods of calculation.
In the past, automated calculation methods were usually available
only on mainframe computers and their use was costly, complicated, and timeconsuming. However, those methods provided much greater accuracy and could
3.8 NEXTRECORD
evaluate building energy use hourly. With the advent of the personal computer,
automated methods for analyzing building energy became accessible to a wider
range of building professionals. Today, many software packages for analyzing
building energy are available for the personal computer.
ASEAM is such a model and was used to analyze the effects of several
of the ECOs discussed above. ASEAM is a modified bin method program for calculating the energy consumption of residential and simple commercial buildings.
ASEAM runs on an IBM-PC and compatibles with at least 256 kilobytes of memory
and two disk drives.
Like most building energy analysis programs, ASEAM performs
calculations in four segments:
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loads - Thermal heating and cooling loads (both
peak and "diversified," or average) are
calculated for each zone by month and by outside bin temperature. Lighting and
miscellaneous electrical consumption are
calculated in this segment.
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systems - The thermal loads calculated in the
loads segment are then passed to the systems'
segment, which calculates "coil" loads for
boilers and chillers. (The system coil loads
are not equal to the zone loads calculated
above because of ventilation requirements,
latent cooling, humidification requirements,
economizer cycles, reheat, mixing, etc.) Some
building energy requirements are calculated in
the systems' segment (e.g., heat pump and fan
electricity requirements).
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plant - All of the systems' coil loads on the
central heating and cooling plant equipment are
then combined, and calculations are performed
for each central plant type. (Plant equipment
can also impose loads on other plant equipment,
such as cooling tower loads from chillers and
boiler loads from absorption chillers or
domestic hot water.) The plant calculations
result in monthly and annual energy consumption
figures for each plant type.
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economic (optional) - Energy consumption from
all the building end-use categories is then
totaled and reported. If specified, the LLCs
of the total energy requirements, combined with
other parameters, are calculated and reported.
In the parametric and ECO calculation modes, a
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base case may also be compared with alternative
cases.
The ASEAM program is recommended as the initial energy-use
assessment tool for residential and commercial buildings. It is relatively
simple and inexpensive to use, does a good job of accounting for the
complexities of energy use, and facilitates the examination of most ECO costs
and benefits. This tool is further discussed in Chapter 4, and example
applications are described in Volume 2 of this A&E guide.
3.5
SELECTION OF SUPPLEMENTAL METERING POINTS
An understanding of energy-use effectiveness is often severely constrained by a lack of scientific data on energy system performance. Measurements taken on a regular basis are most useful to assess energy-efficiency
levels and the effects of operational or design changes. Measurements may be
continuous, such as utility meters, or may be for short periods of time, such as
combustion efficiency tests. Some of the most critical measurements are listed
below:
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electrical consumption levels by type of day
(working and nonworking days) and month of year
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electrical demand levels by hour of day and
season of year
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interior lighting levels, efficacy, and
schedules
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interior temperature levels by hour of day and
season of year
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chiller and boiler efficiency levels under
part-loads
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make-up water requirements for steam and hot
water distribution systems
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exterior temperature, humidity, and solar
radiation
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areas of heated, cooled, and unconditioned
space
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capacity ratings and hours of operation for
major equipment such as pumps, fans, and street
lighting systems
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thermal conductance (U-value) of conditioned
building envelopes
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submetered electrical consumption for major
buildings and equipment loads such as fans,
pumps, lighting, and process equipment
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submetered hot water, chilled water, and steam
measurements for individual buildings and/or
central plant headers
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hours of operation and other facility
production/use factors.
The costs of collecting and processing data are often a significant
barrier to scientific investigations of energy use and conservation potential.
The need for more accurate data must be balanced against the higher costs of
collecting and processing it. Continuing developments in energy metering and
analysis techniques are reducing measurement costs while improving the quality
and amount of data available. While some of the measurements identified above
require sophisticated equipment and skilled technicians, others may be readily
available for the asking from the building designers, servicing utilities, the
National Weather Service, or the O&M staff.
The analyst must verify the quality of the data before incorporating
it into an analysis. Typically, this requires a skeptical attitude on the part
of the user and a comparison of measurements and/or use of engineering calculations. While errors cannot always be found, inaccuracies in major items
such as meter readings, motor capacities, square footage calculations, and meter
multipliers and reading dates should be found and corrected.
To facilitate the identification of metering points and the
collection of data, the FEMP has developed four Mobile Energy Laboratories (MEL)
for application to federal facilities. These laboratories provide equipment,
skilled technicians, and standardized testing and measurement procedures on a
cost-shared basis to federal facilities that are willing to offset the costs
associated with MEL use. If supplemental metering is required, the energy
management committee should consider making use of this capability or obtaining
the professional services of a qualified energy consultant.
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4.0
SIMULATION METHODS
A building simulation is a mathematical representation of the way
in which a building functions. A simulation cannot precisely replicate a real
building because all building simulations are based upon a set of underlying
assumptions. The accuracy of the simulation will be determined by the validity
of the assumptions.
Even if a building simulation were a theoretically perfect representation of how a building functioned, it still could not replicate the actual
operation of the building. Climate can vary annually by ±15%. Systems and
equipment never operate precisely as predicted by part-load performance curves.
Even two apparently identical chillers or boilers can vary in performance by
several percent. Performance will also vary with age of equipment and with the
number of operating hours since the last major cleaning or overhaul. Finally,
no set of operating schedules can duplicate the way people operate and interact
with a building.
Therefore, the results of any building simulation are a relative
representation of how the building does or could function. Care should be used
in interpreting such results in an absolute sense. However, a building simulation is a valuable tool if properly applied and interpreted. For example,
comparisons between two or more systems, made under the same basic set of
assumptions, will yield a valid comparison. Furthermore, for an existing
building, the simulation can be fine-tuned and validated against energy bills
and operating data. A simulation can be adjusted to closely replicate a
building's monthly energy consumption.
A clear and general understanding of a simulation program's methodologies and limitations is essential if the simulation is to be successfully
applied to a particular building. Failure to do this could result in under- or
over-specification of building input data, or could lead to unrealistic
expectations in interpreting simulation results. Therefore, the user is
advised to become familiar with the methodologies used in a building
simulation, especially if a sophisticated or complex analysis is to be
attempted. To that end, this chapter includes a discussion of modeling methods
(Section 4.1), calculation techniques (Section 4.2), and the type and
organization of data (Section 4.3). A discussion of level of detail considerations is presented in Section 4.4.
There are several basic reasons for using building simulations.
The first is for buildings research. Building simulations permit the
researcher to explore the behavior of various types of buildings and their
response to changes in their systems or in building operating strategies.
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Building simulations are an important design tool. They can be
used to examine design strategies, compare various combinations of systems or
components, and explore the impacts of control strategies or operational
requirements. Building simulations can also be used to test for conformance to
a design energy budget.
Building simulations are often used as an aid in selecting and
sizing building systems or components. (They should never be used in place of
the judgment of an experienced design professional, however.) Simulations are
especially useful in evaluating the interactions of two or more systems or
components, a situation which is virtually impossible to deal with manually.
Energy conservation retrofit analysis is another area in which building
simulations are widely used.
Finally, the value of building simulations in the marketing of
building components or systems has always been important. Simulations are a
convincing means of demonstrating to prospective customers the performance of a
given system against competing products.
4.1
BUILDING ENERGY USE SIMULATION MODELS
The evolution of building simulations has paralleled the
development of the computer. Early computer models were written for main frame
computers. Initially, only the largest available machines had the speed and
capacity to perform building energy simulations. Today, some of the microcomputer models are approaching the sophistication of the main frame computer
models. Furthermore, programs such as DOE-2, which were originally written for
main frame computers, now run satisfactorily on mini-computers and can be run,
although slowly, on desktop computers.
Building simulations can be classified in two ways:
simulation and the type of calculation.
the type of
For the purposes of this discussion, simulations can be classified
by the type of analysis: whole building, component, parametric and
sensitivity, and retrofit analysis. Calculations are classified by the time
step used: static, incremental and dynamic.
In this section these two classification schemes are presented,
followed by a discussion of the development of building energy simulations.
4.1.1
Types of Building Energy Simulations
Building energy simulations can be described under one of the
following classifications.
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4.1.1.1
Comprehensive or Whole Building Analysis
In a comprehensive or whole building analysis, the energy
consumption of an entire building is simulated, including the effects of
weather, performance of mechanical/electrical systems, and the building
occupants. A comprehensive analysis is typically used to
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determine long-term energy costs
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examine a design for conformance to an energy
budget
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satisfy energy code compliance
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determine the performance of various HVAC
systems in a given building design
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determine component interactions.
4.1.1.2
Component Analysis
In a component analysis, the energy consumption of a single part of
a building or several integrated parts is simulated. A component might be a
roofing system, a lighting system, HVAC systems, a thermal storage system, or
an atrium. Component analyses can be used to compare the relative merits of
different systems without performing a whole building analysis. The comparison
is relative rather than absolute because interaction with all building systems
cannot be taken into account. However, determining that one system is 50% more
energy efficient than another may be sufficient for system selection.
Component analyses can be used for selecting and sizing components; demonstrating code compliance for specific components; marketing a specific
component by demonstrating its performance in comparison to competing products;
or determining the interaction of two components (e.g., additional roof
insulation and a night setback control).
4.1.1.3
Parametric and Sensitivity Analyses
In both parametric and sensitivity analyses, one or more building
parameters are varied incrementally. In a parametric analysis, the goal is to
optimize building energy performance. For example, different chillers with
unique performance curves and capacities could be examined.
In a sensitivity analysis, the goal is to determine whether an
incremental change in a building parameter has a significant impact on energy
consumption. If this is found to be the case, extra care can be taken in
specifying and installing the building component that is affected. For
example, the performance of a heat pump might be very sensitive to a 10% change
in supply CFM. On the other hand, a furnace may exhibit little change in
efficiency at part-load rates of 50% to 100%, which would mean that the exact
sizing of the furnace is not critical to efficient energy performance.
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4.1.1.4
Retrofit Analysis
This type of simulation is used to examine energy improvements in
an existing building. Either comprehensive or component analyses may be used.
Component analyses are less expensive to perform and are often used. Comprehensive analyses have an advantage in that a base case simulation can be compared with actual energy consumption taken from utility bills.
4.1.2
Life Cycle Costing
Life cycle costing is an integral part of many building simulation
methods. While the purpose of many building simulations is to save energy, the
bottom line for the building owner is to save money. It often makes sense to
complement the building simulation with an equally comprehensive economic
analysis. Since an energy-conserving building will often cost more initially
than a standard building, a life cycle cost analysis is used to compare the
total cost of various designs. Life cycle costing takes into account initial
cost, the cost of money, energy costs, operation and maintenance costs,
component replacement costs, salvage value, and other factors that will affect
cost over the entire life of the project.
4.1.3
Types of Calculations
Another way to characterize or classify building simulations is the
way in which they simulate changes in conditions over time. In this section,
three basic types of calculations are discussed. In Section 4.2, methods and
approximations used in present day building simulations are discussed.
4.1.3.1
Static Calculations
The simplest building energy calculation is a steady state calculation in which all building parameters are fixed. This type of calculation is
used to determine peak thermal loads and has been used by engineers for many
years to size space heating and cooling equipment. However, building
parameters do change over time. Outside air temperature, relative humidity,
wind speed and direction, and solar gain are constantly changing. Building
occupancy, lighting levels, miscellaneous equipment usage, and thermostat
setpoints vary over the course of a day. The operating parameters of building
systems and plants vary as well.
The first attempt at quantifying annual energy usage was
accomplished by the Tennessee Valley Authority in the 1930s. The heating
degree day concept was developed using 65EF as a base. The number of heating
degree days can be calculated and correlated to heating energy requirements by
subtracting 65 from the average daily temperature in EF. Heating degree days
were used in the static peak load calculation in place of the design
temperature difference (indoor-outdoor) to produce an annual, rather than a
peak, heating consumption estimate. Of course, all other variables (such as
heating system efficiency) had a single annual value. This approach worked
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reasonably well for predicting the electrical consumption of populations of
resistance-heated, non-air-conditioned and poorly insulated (by today's
standards) residences. However, it is a poor approximation for modern
commercial buildings with larger internal loads, coincident heating and cooling
requirements, and significant ventilation requirements.
4.1.3.2
Incremental Calculations
One method of improving the static calculations is to perform a
series of calculations at various conditions. The method of accomplishing this
varies from simulation to simulation and is discussed in Section 4.2. The most
common time step is hourly variation. This provides 24 distinct "states" in a
day, 8760 in a year. Furthermore, hourly weather data have been taken at
numerous observation stations worldwide. Because performing 8760 calculations
to determine annual energy consumption requires considerable computer power for
a detailed building simulation, there has been considerable research into
methods of reducing the required number of calculations. Typical day analysis
and bin methods are examples of incremental calculations that require less than
8760 calculations to simulate a year.
4.1.3.3
Dynamic Calculations
In some instances, one-hour time steps are not sufficient. It may
be desirable to study a non-linear passive solar effect.
The fact that the
chiller ran for an hour and satisfied the hourly load in the space does not
mean the occupants were comfortable for the entire hour. Studying the effects
of building mass is another reason for using dynamic calculations. Whatever
the reason, a situation may occur in which something interesting is happening
in between the specified time stops. If the time interval between the
incremental calculations is made infinitesimally small by the use of integral
calculus, the calculations are dynamic and represent the most realistic
simulation of actual conditions possible.
Dynamic calculations can be extremely complex and time-consuming.
The data necessary to verify them are typically available only in specialized
studies. Fortunately, incremental calculations are quite sufficient for most
building simulations.
4.1.4
Development of Energy Simulations
Energy analysis software was first developed in the early 1960s.
Development proceeded from automation of steady state calculations to the
advancement of a variety of component load applications, such as equipment
part-load operating curves. Combining the individual component analyses led to
the first energy analysis programs.
Whole building energy analysis software was originally developed in
the private sector. In 1967, the American Gas Association (AGA) launched its
Gas for the Advancement of Total Energy (GATE) Program. The purpose of this
program was to market gas-powered total energy systems for building complexes.
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Energy analysis software was used to show building developers the benefits of
total energy systems compared with conventional systems. The approach was
successful, and in 1971, AGA introduced the E-CUBE computer program. Other
utility groups also developed software. The Edison Electric Institute (EEI)
introduced its AXCESS Program in 1971 as well.
The first large-scale program to be developed by a federal agency
was also introduced in 1971. The U.S. Post Office developed the USPO Program
to analyze double-bundle heat recovery systems and other energy-conserving
designs they were investigating for use in their buildings. Many of the features of this program were incorporated into later public and private sector
models. The first comprehensive energy analysis program to be developed by a
profit-making company was the TRACE, Program, introduced by the Trane Company
in 1973.
The oil embargo of 1973, and the resultant need for a national
energy policy, led to the large-scale development of public sector energy
analysis software. In 1977, DOE's predecessor, the Energy Research and
Development Administration (ERDA), and the State of California introduced the
CAL-ERDA Program. This program has evolved into the DOE-2 Computer Program,
which is supported by the Lawrence Berkeley Laboratory for DOE. At the same
time, the U.S. Army Civil Engineering Research Laboratory developed the
Building Loads Analysis and System Thermodynamics (BLAST) Program. These
programs have been continuously supported and updated since their introduction.
They have furthered the art of building energy analysis, and many of their
features have been incorporated into private sector programs. While both of
these programs were originally written for main frame computers, mini-computer
versions are now available. The DOE-2.1C version can also be run on a desktop
computer using proprietary software.
In the late 1970s and 1980s, literally hundreds of energy analysis
computer programs were developed (ASHRAE 1986). They are used for building
research, energy analysis, education, load forecasting, marketing, and as
design tools. Much of the software development has centered around ease of
input. Program output is targeted to the needs of the user and may now include
graphics. As the capacity of desktop computers increases, there is emphasis on
models that the user can purchase and run in-house on a personal computer (PC).
DOE-2 and BLAST, however, remain the standards against which other programs are
measured. The following is a brief description of some of these programs.
4.1.5
Main Frame Simulation Programs
The two major public sector programs continue to be DOE-2 and
BLAST. Both of these programs have been supported and updated numerous times
since their introduction. DOE-2 and BLAST use sophisticated hourly load calculation methods, which take into account the climate, operating schedules, and
interactions with the building mass. Their major difference is in the
mathematical methods used to calculate space heating and cooling loads. Both
,
Registered trademark of American Standard Inc., New York, New York.
4.6 NEXTRECORD
use curve-fit equations to determine system and plant equipment part-load
performance. However, the actual performance of a specific type of equipment can
be input by an experienced user. Both programs can simulate most building system
and plant combinations, and they contain integrated life cycle costing software
for economic evaluation. DOE and BLAST also differ from other programs in their
use of building descriptive languages and free form input. This is discussed in
Section 4.3.
Three of the most widely used main frame private sector programs are
AXCESS, developed by the Edison Electric Institute; E-CUBE, developed by the
American Gas Association; and TRACE, developed by the Trane Company. These
programs rival the public sector programs in their degree of sophistication.
Since these programs target an audience made up of engineering and marketing
support, their programs use fixed format rather than free form input.
4.1.6
PC-Based Simulations
The two major public programs written for PCs are the BESA(R) programs
developed in Canada and the ASEAM program developed in the United States. The
BESA programs are a design tool series. Five basic packages dealing with predesign, concept, detailed design, building commissioning, and retrofit are being
developed. Some of the packages have multiple versions targeted for different
users such as architects, engineers, and building managers.
Except for one version of the detailed design program, which is an
hour-by-hour analysis designed to run on a mini-computer, all of the packages use
the bin method for energy analysis. Peak demand is calculated using a one-day
per month simulation. The program uses an interactive input routine, supports a
variety of systems, and has a parametric processor for detailed investigations.
ASEAM was designed as both a research and educational tool and a design
tool. It also uses a bin methodology for calculations. System and plant
algorithms are similar to those in DOE-2. The program has an interactive input
sequence, as well as a simplified input where many variables are defaulted. Online error checking and help screens aid program input. The program can be used
to run building energy analysis, ECO analysis, and parametric analyses. Life
cycle costing modules are built into the program.
Input is designed to facilitate the execution of multiple runs, either as
ECOs, or as a parametric analysis of one or several ECOs. Program calculations
can be displayed or printed during execution. The program graphical display
permits the user to visualize load, system, and plant energy flows for each
calculated outside air temperature. The program output permits the user to
specify any of a series of engineering reports, which can be displayed, printed,
or saved as a file. Output report files can be saved as spreadsheet files to
produce graphs or for additional analyses. Output reports can also be read into
a word processor for incorporation with text.
────────────────
(R) Registered trademark of Societe Canadienne des Brevets et d'Exploitation
Limitee, Ottawa, Ontario, Canada.
4.7
Three of the most commonly used PC-based simulations that have been
developed in the private sector are ACES, TRAKLOAD, and ADM-3. All three
programs run on IBM-compatible PCs, and all support PC-DOS and MS-DOS.
As private sector programs, they are targeted to building energy audits.
They have interactive input sequences. ACES and TRAKLOAD provide for automatic
specification of energy conservation measures, graphical output, and usertailored output reports. ACES and TRAKLOAD incorporate economic analyses. All
three programs accommodate multiple building zoning and a variety of HVAC system
and plant simulations. The models vary as to the specific HVAC systems supported
and whether the effects of thermal mass are considered. They also vary in their
treatment (or lack thereof) of factors such as latent heat, refrigeration
(freezers and coolers), and daylighting.
The major difference among the programs is their method of calculation. ADM3 is an hourly simulation, while ACES and TRAKLOAD use the bin method for load
analysis (see Section 4.2.2 for a description of the bin method).
4.2
CALCULATION TECHNIQUES
This section contains a discussion of the application of three
calculation types: static, incremental and dynamic. Included in the
discussion are one static simulation; three incremental simulations; and one
network-type model whose simulations approach the complexity of a dynamic
simulation.
4.2.1
Variable Base Degree Day Method
When a fast and inexpensive approximation is required, the degree day method
is still used. To compensate for the increased insulation, internal gains, and
decreased infiltration that is standard practice in buildings today, heating
degree days are calculated based upon temperatures other than 65 deg. F. The
building's balance point (temperature above which heating is not required) is
estimated. Heating degree days are calculated based upon this new temperature,
and annual heating energy requirements are estimated. This methodology should be
used to estimate the heating requirements of simple buildings only.
4.2.2
Modified Bin Method
The modified bin method, developed by ASHRAE's technical committees, is a
technique used to calculate annual energy consumption without performing 8760
discrete calculations. For example, the building load can be calculated at an
outside air temperature of 47.5 deg. F. That load is then assumed to be
representative of all of the hours when the outside air temperature is between 45
deg. F and 50 deg. F. One calculation can be performed for each 5 deg. F change
in outside air temperature. Each calculation is multiplied by the number of
hours in its respective "bin"; in other words, the number of hours when the
outside air temperature is within 2.5 deg. F of the temperature used in the
calculation. Typically, 5 deg. F bins are used, although the method will work
with larger or smaller bins.
4.8
In the modified bin method, the calculations are performed monthly or
annually, and for occupied and unoccupied building hours. Thus, several hundred
calculations are used to characterize building energy consumption, rather than
8760. The modified bin method accurately predicts annual building energy
consumption. This methodology compares well with hourly simulations, and can be
used with system and plant algorithms which are almost as sophisticated as those
used in hourly simulations. The modified bin method executes rapidly enough to
be used on desktop computers and is also applicable to parametric analyses.
One major shortcoming of the modified bin method is its inability to
accurately calculate peak demand. This calculation is best addressed by
typical day or hourly methods.
4.2.3
Typical Day Method
In a typical day method, the simulation is executed hourly for one or more
consecutive 24-hour periods. This type of simulation is used to
determine daily load profiles that cannot be calculated using averaging
techniques, such as the modified bin method. The affects of building mass and
hourly solar gain, which average out over the course of a month, have significant
impact on hourly demand calculations.
In practice, a typical day simulation is executed for three or four
consecutive days, often using the same weather conditions for each day. This
permits the model to reach an equilibrium state by eliminating
discontinuities which occur at model startup. Typical day calculations can be
performed for a peak winter day, a peak summer day, and one or more intermediate
days. This procedure permits characterization of daily load profiles through-out
the year.
Several typical days per month can be simulated and these simulations can be
used to project annual energy consumption. Considerable research was conducted
in this area in the late 1970s and early 1980s. At that time computer capacity
and speed limited the use of hourly simulations, and sophisticated bin methods
had not been developed. Given the speed and power of modern machines, current
practice is either to run 8760 hourly simulations or to use a modified bin method
approach to estimate annual energy consumption.
4.2.4
Hourly Method
The benchmark computer programs such as DOE-2 and BLAST use an hourly
simulation method. Load calculations are performed for each hour of the year,
using historical hourly weather data. The effects of thermal mass on changes in
loads are taken into account. Detailed schedules can be specified for occupancy,
lighting, miscellaneous equipment loads, ventilation, and control setpoints. The
building loads are passed to the system portion of the model where the operation
of air handling equipment and packaged systems are simulated. Finally, system
requirements are passed to the plant portion of the model for simulation of
boilers, chillers, and cooling towers. Hourly simulations are typically used for
large complex buildings.
4.9
4.2.5
Network Methods
Network methods are used to simulate the response of complex systems. They
are typically employed where multiple modes of operation are possible, where nonlinear effects occur, or where transient responses are important. These
simulations approach the complexity of dynamic calculations, and time-steps
shorter than one hour are typical. The input requirements and computer time
necessary to simulate one system can be as extensive as those for a whole
building hourly analysis.
An example of a network model is the TRYNSYS computer program. Here, a
simulation is built up from modules representing individual generic pieces of
equipment such as pumps, valves and controllers. For example, in a solar
simulation, energy gathered by the solar collectors can be delivered to the
space, domestic water heating, or a heating storage tank, depending upon the
requirements at a specified point in time.
Highly trained operators typically use network models for buildings
research because of their flexibility and complexity.
4.3
NATURE OF INPUTS REQUIRED
Building simulation begins, ideally, with the accurate specification of the
building, its systems, and its schedules. In this section, the type and
organization of data required for most simulations is discussed. Level of detail
considerations are presented. The types of building input formats currently in
use are discussed. Finally, sample input sequences are described using ASEAM as
an example.
4.3.1
Type of Data Required and Organization
Six types of data input may be required for a building simulation:
o
building operation
o
building envelope
o
secondary distribution systems
o
central plant equipment
o
weather data
o
economics (optional).
These data are normally organized as discrete modules to afford
flexibility in the execution of multiple runs. For example, the heating and
cooling requirements of a building can be calculated in a module called building
loads and subsequently be used to evaluate various types of HVAC systems.
4.10
Alternatively, the same building can be simulated in various climate regimes by
executing a simulation with different weather data.
The building is typically divided into zones before the building input is
developed. A zone is a portion of the building that shares common features,
which may include
o
use and operating schedule
o
thermostat setpoints
o
similar loads (e.g., lighting watts/ft└2┘ and equipment watts/ft└2┘)
o
HVAC system type
o
outside wall exposure.
For example, all of the south exposure classrooms in a school could be
modeled as a single zone. The cafeteria, mechanical rooms, swimming pool, shops,
offices, auditorium, and gymnasium might be separate zones, even though their
percentage of building floor area might be small. Other areas such as restrooms
and storerooms might be combined or added into other zones if their impact on
building energy usage is minimal. A small office building might be divided into
a core area and four perimeter zones (N,S,E,W) to isolate solar effects. The
goal is to break the building into several discrete areas that accurately
represent the different areas, exposures, and activities within the building.
Oftentimes, these zones will be the areas served by particular HVAC equipment.
Specifying too many zones may increase the work of the user, but not appreciably
improve the accuracy of the simulation.
Once the zones have been defined and the loads portion of the input is
completed for each zone, the input data for the secondary distribution
systems is completed. Zones are assigned to the systems that serve them.
Plant input information is then completed, and the plant equipment is
assigned to the respective systems. Weather data are specified, and, if
desired, economic information is completed.
The information required for each section of data input is outlined
below. Note that in many building simulation models the simulation can use
default values for system and plant performance to size systems and plant
equipment to meet the peak building loads.
4.3.1.1
Loads
This section is commonly referred to as the building loads portion of the
input. It combines information on the building shell and operation to calculate
the heating, cooling, lighting, and plug loads. Both building-specific and zonespecific data are required. The following are examples of the type of
information that is specified:
4.11
o
floor area
o
number of zones and zone identification
o
area by zone
o
thermostat schedules and setpoints
o
occupancy schedules
o
sensible and latent heat gain from people
o
exterior wall construction type and area
o
roof construction type and area
o
window construction type and area
o
door construction type and area
o
underground wall construction type and area
o
window shading and overhang geometry
o
miscellaneous conduction paths (e.g., freezer walls)
o
lighting watts/ft└2┘ and schedules
o
heat of light to space
o
miscellaneous equipment, schedules, and heat to space
o
infiltration rates.
4.3.1.2
Secondary Distribution Systems
This section includes both distribution systems such as air handlers and
unitary equipment such as heat pumps. The following types of information are
typically specified:
o
system capacity and type
o
zone assignments to systems
o
heat source for systems (plant type)
o
cooling source for systems (plant type)
o
system availability and schedules
4.12
o
system-specific information (as required) such as deck temperatures,
controls, outside air and damper control, humidification, preheat and
reheat, fan power and CFM, loop temperatures, and backup heating
o
unitary system information (as required) such as design COPs for
air conditioners and heat pumps, efficiency and parasitic losses
for furnaces, and unloading ratios for DX systems.
4.3.1.3
Plant
This section includes the specifications of the primary energy-using
systems such as boilers, chillers, cooling towers, circulating pumps, and
domestic water heaters. Plant data are filled out for the equipment and
typically include the following information:
o
plant types (if not specified in system input)
o
fuel types and costs
o
miscellaneous equipment consumption (if any)
o
cooling plant specifications such as number of units, capacity,
design COPs, controls, unloading and part load ratios, water
temperatures and flow rates, load management system specifications,
and pump kWs
o
cooling tower specifications such as heat rejection capacity,
number of cells, fan kW per cell, water temperatures and flow
rates, pump kWs, approach temperature, and controls
o
domestic water specifications such as fuel source, heating
capacity, average usage, inlet and supply temperatures, circulation
pump kW and scheduling, design efficiency, and standby losses.
o
boiler specifications such as energy source, number of units,
capacity, design efficiency, controls, minimum part-load ratio,
boiler pump kW, and standby/parasitic losses.
4.3.1.4
Weather Data
Weather data are typically part of the building simulation and are
specified by site location. The user must select an available weather
station that most closely corresponds to the location of the building being
simulated. Some simulations permit the user to create a weather file for a
specific location or application. Weather data typically used in a building
simulation include:
o
air temperature
o
relative humidity or humidity ratio
4.13
o
wind speed
o
wind direction
o
insolation or cloud cover.
4.3.1.5
Economics
If the user wishes to evaluate the life cycle cost of a building or to
compare the economics of various building systems or retrofit alternatives, an
economic analysis module is used. Typical inputs for such a module include:
o
energy rate costs
o
energy cost escalation factors
o
inflation rate
o
capital cost
o
annual maintenance costs
o
periodic overhaul costs
o
useful life
o
salvage value
o
replacement costs
o
depreciation rate and methodology
o
finance charges
o
owner's minimum acceptable rate of a return on investment.
4.3.2
Level of Detail Considerations
The level of detail specified for building data is, to a great extent, under
the control of the user. In this section, level of detail
considerations are discussed, followed by a more detailed description of
load, system, and plant input.
The level of detail that can be achieved in a particular building
simulation is limited by the capabilities of the simulation model itself and the
information available on the building. If the simulation is addressing the
design of a new building, the level of detail can be increased as the design
progresses. The desired level of detail is also driven by the goal of the
simulation. For example, if a daylighting system is being examined, the
orientation and reflectance of building surfaces is very important. If alternate
building HVAC systems are under study, the disposition of heat of light, the mass
of building materials, and solar heat gain through fenestration are important.
4.14
Over- or under-specification of building parameters is a common mistake
among inexperienced users. Under-specification leads to inaccurate results.
Over-specification, beyond the accuracy limits of the simulation,
complicates the input with no advantage in simulation accuracy. Some items that
should be considered are as follows:
o
The building should be zoned by major functional uses or to isolate
energy systems under study. Similar spaces, such as nearly
identical floors or exposures in a high rise office building, can
be grouped in a single zone.
o
The energy consumption of many buildings is sensitive to the amount
of infiltration specified. This is also a difficult quantity to
determine in an existing building. Care should be taken in
specifying the infiltration rate.
o
If lighting comprises a large percentage of building energy usage,
the lighting schedule and heat of light transmitted to the space
are important quantities.
o
The energy consumption of miscellaneous equipment may be
significant, and actual usage may be difficult to specify.
o
In examining architectural alternatives, it is common practice to
default system and plant variables and minimally specify
miscellaneous equipment. This will result in a relative comparison
of the architectural features being studied. However, the overall
result may be undesirable. For example, excess insulation
for the roof of a core area housing computers may be ineffective
because of internal heat gains. Accurate specification of the
computer equipment will display the need for cooling in winter, and
may result in consideration of a heat reclamation system.
o
If the heat or cooling plant equipment size is determined by the
model, without specification of plant oversizing, the simulation
will size the plant just large enough to accommodate system
requirements. The simulated plant will then operate at a higher
part-load and greater efficiency than that of the actual plant
equipment.
Producing accurate building input files requires that the user have a good
physical understanding of how buildings operate and use energy. Once the level
of detail to be considered has been determined and the building has been zoned,
the process of building takeoff and simulation input can begin.
4.15
4.3.3
Building Simulation Input Formats
The three formats for building simulation input are 1) fixed format, 2) free
format, and 3) interactive. Most simulations use only one of the three.
However, the BLAST program has a free form input and a version that uses
fixed format.
4.3.3.1
Fixed Format
Fixed format input was developed first. At the time, the only access a user
had to a computer was through a deck of computer cards. The cards had to be
submitted in the proper order. All information had to be entered in the proper
column. Much of the information was coded. For example, the type of chiller
might have been specified in columns 3 and 4 of Card Number 8, by entering the
proper code number. Today, entry would occur at a terminal rather than by
creating cards, but a similar process is used. The advantage is that the user
can be led through a specific input process. The disadvantage is that the
process can be tedious, since the input format must be completely filled out.
4.3.3.2
Free Format
The writers of DOE-2 and BLAST departed from the rigidity of fixed
format input by creating free form input. They developed a building
descriptive language (BDL) that permitted the user to create an input
sequence based upon the building being simulated. An example from the DOE
program is
CHILLER=PLANT-EQUIPMENT
TYPE=HERM-CENT-CHLR
INSTALLED-NUMBER=1
SIZE=2.16 ..
The first line tells the computer that the information which follows
deals with chilled water equipment in the central plant. The second through
fourth lines, which can be entered in any order, specify that there is one
hermetic centrifugal chiller rated at 2.16 x 106 Btu/hr. Free format input
permits very rapid specification of a building simulation, provided the user
learns the BDL and uses it often enough to stay familiar with it. The BDL also
requires sizable computer memory.
4.3.3.3
Interactive
Interactive input is most commonly used for building simulations that run on
desktop computers. A series of input screens is used to prompt the user for
information. The more sophisticated simulations have edit features, similar to a
word processor, and on-board help screens to assist the user. The input process
is rapid because unnecessary screens and lines of input are skipped
automatically.
4.16
Interactive input has two other advantages. First, gross input errors are
caught immediately. For example, if the space temperature is
accidentally input as 8 deg. F or 800 deg. F, an error message appears. With
fixed or free format input, this type of error may not be caught until the start
of execution. Second, if default values are specified, they are immediately
displayed for the user.
4.3.4
Example of Simulation Model Inputs
Only a small number of data inputs need be specified for a simple and
standard building. However, the complete variable listings are described to
indicate the wide variety of building and operational alternatives that can be
modeled.
The following sections describe the input variable options for ASEAM
Version 2.1. This model is a good example of a full feature desktop computer
simulation model for use by engineers. Appendix B provides an abbreviated
listing of the input variables for the ASEAM model. Where applicable, the name
of the data input screen is indicated in the first column.
The actual entry of these data into the model is done with numerous
"user friendly" screens. Each screen provides a menu of the input options and
available defaults. Once entered, the data are checked for
reasonableness. The inputs can subsequently be altered by re-entering the screen
or by using a parametric processing model. Chapter 2 of Volume 2 describes these
input screens in detail.
4.3.4.1
Building Load Data Inputs
The building shell or loads portion of the input is typically completed
first. It is divided into general building information and zone-specific
information.
The general building data are divided into three sections as shown on page
B.2 of Appendix B. The first contains building and project identifiers, the
square footage of the total building and conditioned spaces, and the number of
zones. This section also contains latitude, longitude, and operating and
occupancy information. The second section contains shading information, which
permits the user to specify the external shading on three different types of
windows. The third section permits the specification of up to four different
monthly operating schedules.
Pages B.3 and B.4 contain information that is completed for each building
zone. The data are divided into 13 sections. The first section contains zone
identification, zone area and volume, and temperature setpoints. The second
section permits the specification of up to four different lighting systems for
each zone. If a daylighting option is specified, the next two sections of data
are completed; otherwise, they are omitted. These sections permit specification
of daylighting information and dimmer or stepped control for one or more of the
lighting systems specified in the second section. The next section permits
specification of building occupants and the heat gains associated with them.
4.17
The next two input sequences deal with miscellaneous electrical
equipment and sensible heat gains. Note that diversity factors can be
specified for occupied and unoccupied conditions, as well as on a monthly
basis. Sections 8 through 11 are used to specify walls, roof, windows, and
doors. Each zone can be modeled with up to four types of walls and
windows and up to two types of roofs and doors. Mass and color correction, area,
and U value can be specified for walls and roofs. Windows can be shaded, and the
infiltration of both windows and doors can be specified using a crack method. In
addition, infiltration can be specified on an air change basis in the twelfth
section of input. The last section deals with miscellaneous conduction losses
and can be used to simulate a floor over an unheated space or a wall adjoining a
freezer. This completes the building shell or loads section of the simulation
input.
4.3.4.2
HVAC Systems Data Inputs
Secondary distribution systems input includes the zone to system
assignment and the description of each system. The information shown on page B.5
of Appendix B is completed once for each building. It enables the user to define
which systems are present in the building and which zones they serve.
The information entered is used by the simulation to display the
appropriate sections (13 total) of pages B.6 and B.7 for each system that has
been identified. The first four sections deal with coils in air systems which
add heating, cooling, preheating, and humidity. The type of plant is specified,
as are the availability and control of the conditioning coil and the discharge
temperature. The fifth section is used to specify baseboard heating systems.
The sixth and seventh sections are also used for air systems to specify the fans
and outdoor air control. The eighth and ninth sections are used to specify the
cooling and heating of heat pumps. The tenth and eleventh sections are designed
for the specification of furnaces and circulation fans. The twelfth section is
used to enter information on DX systems. Note that many of these systems can be
autosized and that a percentage of oversizing can be specified. The final
sections are designed for user-entered values or capacities (instead of
autosizing). This completes the input of building systems.
4.3.4.3
Plant Equipment Data Inputs
The plant input data are next. The information (shown on pages B.9 and B.10
of Appendix B), which is divided into nine sections, is filled out once per
building. Only the appropriate sections are completed for a given building. The
first two sections permit specification of energy types, conversion factors,
costs, and miscellaneous plant energy consumption. The next four sections deal
with four different types of chillers. Sections are completed for the chiller
types in use in the building. Specification includes number of chillers,
capacity, design COP, unloading and part-load ratios, and control. Note that the
chillers can be autosized. The seventh section of input is for the specification
of cooling towers.
4.18
The eighth and ninth sections are for the specification of domestic
water systems and boilers. The input sequence permits specification of
heating efficiency and parasitic and standby losses. Both plants can be
autosized. This completes the plant input section of the simulation.
4.3.4.4
Economics Data Input
The previous data inputs were used to calculate the energy requirements of
the building; whereas, the rest of the inputs are used to calculate the life
cycle costs of energy conservation measures. The inputs available for Federal
Building Life Cycle Costing (FBLCC) (shown on pages B.11 and B.12 of Appendix B)
include seven sections. General project information can be input to describe the
measures being evaluated. Capital Component Data input provides information on
the initial cost of the measure, while the Cost Phasing Schedule input allows
these costs to be spread over time. Replacements to Capital Components allow
entry for any recurrent capital costs associated with the measure, such as lamp
replacements for a lighting fixture retrofit. Operating and Maintenance costs
can be entered either on a regular annual basis or an irregular basis. Finally,
energy cost data and energy escalation rates can be entered.
4.4
SINGLE SIMULATION
Once loads, systems, plants, and optional economic inputs are completed, a
baseline simulation can be executed. Before proceeding, the user should
carefully review all input variables. A great deal of information has been
specified, and one small error can lead to large discrepancies in simulation
results.
4.4.1
Running the Baseline Case
The baseline case can now be executed. For ASEAM, the user selects the
"Specifying Analysis" option. This permits selection of a single run, ECO
analysis, or parametric analysis. The single run option is selected. The user
can then specify the load, system, plant, and the economics files (optional) that
are to be used in the run (multiple building files of each type could have been
created before the simulation is run). The weather file to be used is also
selected at this time. Finally, the user specifies which output reports are to
be produced. The "Run Calcs" option is then selected, and the building
simulation is executed.
Once the run has been completed, the results should be carefully
checked. If an existing building has been modeled, the energy consumption can be
verified against actual bills. It may be necessary to edit the baseline files
and re-execute the run. The user should have an intuitive feel for how the
building uses energy. Consumption for various items such as lighting, cooling,
and fans can be checked for reasonableness. Some of the limitations of building
simulations are discussed in Section 4.7.
4.19
4.4.2
Changing Inputs for ECOs
Once the user is confident that a good baseline run has been executed,
various ECOs can be analyzed. Some types of simulation methodologies are not
appropriate for all the types of ECOs that can be analyzed. Table 4.1 summarizes
the applicability of three simulation methods to the major ECOs. Note that some
types of ECOs cannot be simulated well by any methodology. For example,
simulation of a vestibule requires the user to guess the infiltration through a
door before and after the installation of the vestibule. While the "guess" may
be an educated one, the infiltration cannot be specified as precisely as a wall
U-factor or a lighting load in watts/ft2. Some items, such as demand reduction,
require the use of an hourly method. Furthermore, not all of the models using a
given methodology can address all ECOs specified. The user should have a good
idea of the ECOs to be analyzed before selecting a simulation model.
Some care should be taken in selecting and grouping ECOs for analysis. Some
ECOs such as domestic water heating and lighting do not interact. They can both
be modeled in the same ECO run, and the energy savings of each item discretely
determined. Other ECOs do interact. Increased roof insulation will reduce the
savings achieved by night setback. A reduction in lighting level increases
heating energy consumption and decreases cooling energy consumption. Thus, ECOs
that interact may have to be analyzed separately and then in combination.
Unfortunately, the number of possible ECO combinations grows exponentially with
the number of ECOs being analyzed. To run three
ECOs alone and in all possible combinations requires seven discrete computer
runs. For ten ECOs, 1023 runs would be required. One approach is to run each
ECO, then select only the most promising combinations of ECOs for combined
analysis. If large numbers of analyses are required, a parametric processor
should be used. This is discussed in Section 4.5.
To run ECOs, the base case input files must be edited. For some
simulations, such as DOE-2, the user must find the line(s) of code in the
input file to be edited, make the changes, and save the file under a
different file name. The ECO is executed by performing a run using the new
files. In other simulations, such as ASEAM, the process is automated. When
using ASEAM, the user selects the ECO option under data input. A series of menus
permits the user to select load, system, and plant ECO types. For each ECO
selected, a description can be entered. The specific inputs that must then be
changed are displayed on the screen for editing.
Once all ECO inputs have been entered, the user selects the "Specifying
Analysis" option to set up the simulation runs. The ECOs can be run individually
or in user-specified combinations. As previously noted, it is often appropriate
to run ECOs individually before selecting combinations for analysis. Up to 40
ECOs can be specified at once and run in a batch mode. The user should first
ensure that disk space is adequate to store all of the output files that will
result. The ASEAM output reports available when using the parametric or ECO run
mode are more limited because of the potentially large number of runs executed.
4.20
TABLE 4.1.
Applicability of Simulation Methods to ECO Analyses
Simulation Method
────────────────────
Degree
ECO TYPE
Day
Bin
Hourly
──────────────────────────────────────────────── ──────
──────
──────
Reduce space heating and cooling operating hours
Poor
Good
Good
Reduce ventilation system operating hours
Poor
Good
Good
Reduce water heating system operating hours
Good
Good
Good
Reduce equipment operating hours
Fair
Good
Good
Adjust space temperature and humidity settings
Fair
Good
Good
Reduce conduction through building surfaces
Fair
Good
Good
Water vapor barriers
Poor
Fair
Fair
Color and texture changes of building surfaces
Poor
Fair
Good
Multiple glazing
Fair
Good
Good
Movable insulation
Fair
Good
Good
Window tinting and shading
Poor
Fair
Good
Infiltration and air flow through windows
Poor
Fair
Fair
Revolving doors and vestibules
Fair
Fair
Fair
Reduce ventilation
Fair
Good
Good
Reduce indoor pollution
Poor
Poor
Poor
Air cleaners
Fair
Fair
Fair
Improve chiller efficiency
Poor
Fair
Fair
Improve boiler or furnace efficiency
Poor
Fair
Fair
Improve air conditioner or heat pump efficiency
Poor
Fair
Fair
Reduce energy for tempering air supply
Poor
Good
Good
Energy-efficient cooling systems
Poor
Fair
Fair
Attic ventilation
Poor
Good
Good
Reduce distribution system losses
Poor
Fair
Fair
Reduce system flow rates
Poor
Fair
Fair
Reduce system resistance
Poor
Fair
Fair
Reduce hot water loads
Good
Good
Good
Reduce hot water heating system losses
Fair
Fair
Fair
Energy-efficient water heating systems
Fair
Fair/Good Fair/Good
Reduce illumination requirements
Fair
Fair/Good Fair/Good
Retrofit energy-efficient lighting systems
Fair
Good
Good
Use daylighting
Poor
Fair/Good
Good
Reduce power system losses
Fair
Fair
Fair
Use energy-efficient motors
Fair
Good
Good
Reduce peak power demand
Poor
Fair
Good
Use energy management and control systems
Poor
Good
Good
Demand limiting control
Poor
Poor
Fair/Good
Heat reclaim systems
Poor
Fair/Good Fair/Good
4.21
4.4.3
Comparing Output for Effect of ECOs
The effect of implementing a given ECO, or combinations of ECOs, can be
determined by comparing output reports from the ECO run against those
produced in the base case run. It is helpful if the user has some idea of
what to expect when an ECO is simulated. For example, additional roof
insulation will decrease the building heating load. However, if the building
has large internal heat gains, the cooling load may increase, rather than
decrease. The user should also determine if the percentage of change in
energy consumption is realistic.
4.5
PARAMETRIC ANALYSES
If the user wishes to examine the effects of incremental changes in a
given building parameter, or several building parameters in combination, a
parametric analysis can be specified. A parametric analysis permits the
efficient input and execution of a series of simulations.
4.5.1
Evaluating Parametric Combinations of ECO Variables
In the parametric analysis mode, a series of input variables can be
changed. For example, in ASEAM, the parametric processor can sequentially
evaluate up to 10 separate values for up to 20 variables. For each variable,
either a new value or the percentage change from the original value is
specified. If a life cycle cost analysis is desired, a cost is entered for
each value as well. The ASEAM parametric processor produces several output
report files. The first file is a matrix of user-specified input variables,
which compose the changes in each run. The second file is a user-specified
matrix of output variables for each run. Other output files contain monthly
energy consumption, zone peak loads, and life cycle costing summaries, if
desired.
The output consists of summary matrix tables, rather than the full
complement of output reports available in a standard ECO simulation. Once
the optimum combination of variables has been determined parametrically, the
user may find it desirable to execute a standard ECO simulation for that case.
4.5.2
Variables That Can Be Changed
The 20 input variables that can be changed in a parametric simulation
using ASEAM are selected from the list in Appendix C (pages C.2 through C.6).
The choices permit changes in most input variables. Items that cannot be
changed include zoning, areas of building surfaces, and system and plant
assignments.
ASEAM also permits the selection of up to 20 output variables from the
list on pages C.9 and C.10 of Appendix C. These are energy consumption
variables by fuel type, by system or plant, or by heating mode.
4.22
4.5.3
Limitations on Variables
Although the ASEAM parametric processor has been designed to execute as
efficiently as possible, a run may take several minutes. It is advisable to
time one run and determine in advance how long it will take to execute all of
the runs to be specified. For example, if each run takes five minutes, and
180 runs are desired, 15 hours will be required to complete the run sequence.
4.6
INTERPRETING RESULTS
The results of a building simulation analysis are summarized in the
output reports. These consist of energy usage reports and (optional)
economics reports. The type and level of detail presented in the simulation
reports should be considered when a building simulation methodology is
selected. The following two sections contain discussions of energy usage and
economic output reports, using ASEAM as an example.
4.6.1
Changes in Energy Use
The energy use reports should be examined first. Obviously, the energy
simulation must be verified as accurate or the economic analysis will be
meaningless. ASEAM can produce a wide variety of reports that the user can
examine to interpret results. In an ECO analysis, the revised analysis
reports are compared with the baseline simulation reports to determine
changes in energy usage.
The most comprehensive output report is the building end use or BEPS
report, as shown in Table 4.2. This is a summary of building energy
consumption by use category, fuel type, Btu, and cost. This report is used
to determine the total energy and dollar savings of an ECO, as well as the
categories in which the savings occurred. To check the results presented by
this report, the user should examine the more detailed reports. Examples of
these follow.
Table 4.3 is an example of a loads report. It is a tabulation of the
peak heating and cooling loads by component. If an item such as roof
insulation were changed, this table could be used to check the roof
conduction load manually at two extreme climate conditions, thereby assuring
the user that the simulation program is performing as expected.
Table 4.4 is a sample of a systems output report for a variable-airvolume (VAV) reheat system. The plant loads of the system for occupied hours
in January, February, and March are shown. The report can be scanned to check
the months and outside air temperatures when the various systems' loads
occur. It can also be used to check the relative sizes of the loads and
their variance with outside air temperature.
Table 4.5 is an example of tabular ASEAM reports that can be imported
into the Lotus 1-2-3 Program[a] for further manipulation or graphing. In
this example, the operation of a boiler is summarized for the occupied cycle
in January, February, and part of March. Table 4.5 permits the user to check the
behavior of the boiler relative to efficiency and fuel consumption at
every operating condition. Thus, the behavior of the simulated boiler can be
thoroughly compared with that of an actual boiler.
If the user desires further detail, ASEAM provides two other types of
reports. However, the user must review or print them during simulation
execution, as they are too voluminous to save.
4.23
TABLE 4.2.
Sample ASEAM2 Building End Use Report
ASEAM2 Report: BLDG-END USE
Date: 04-07-1987
Sample Single Run Calculation
*
Heating Energy
──────────────
Electric Resistance
Electric Boiler
Building Annual Energy by *
* End Use and Fuel Type *
Nat Gas
(THERMS)
────────
Cooling Energy
──────────────
Reciprocating Chiller
Domestic Hot Water Energy
─────────────────────────
Domestic HW Heater
Electric
(KWH)
────────
Site
(MBTU)
────────
163
87,196
0.56
297.60
18,072
61.68
420
42.05
Building Miscellaneous
──────────────────────
Lights
Equipment
29,409
3,259
100.37
11.12
System Miscellaneous
────────────────────
Fans
12,283
41.92
1,617
2,685
5,000
5.52
9.16
17.06
1.00
Plant Miscellaneous
────────────────────
Cooling Tower
Pumping
Exterior Lighting
Kitchen Range
Consumption Totals
Unit Cost
Dollar Cost
Site Energy (MBTU)
Source Energy (MBTU)
10
430
$0.500
$215
43.0
43.0
4.24
159,685
$0.075
$11,976
545.0
1,852.3
$12,192
588.1
1,895.4
TABLE 4.3.
Sample ASEAM Loads Report
Sample Single Run Calculation
Loads Report File: demoLAOO
Report: Peak Load Summary
Space: Building
Floor Area: 5,000 sq ft
Time of Peak
Outside Temp
Glass Solar
Glass Conduction
Wall Conduction
Roof Conduction
Opaque Solar
Door Conduction
Misc Conduction
Occupants
Lights
Equipment
Misc Sensible
Infiltration
Total
Total Load/Area
Volume:
50,000
COOLING
Apr hour = 17
87.5 deg F
Sensible
(BTUH)
────────
29,365
8,336
4,095
9,750
25,226
0
0
3,275
31,972
3,840
0
17,666
──────
133,526
26.7
cu ft
HEATING
Feb hour = 5
-2.5 deg F
Latent
(BTUH)
──────
3,040
──────
(BTUH/FT└2┘)
Sensible
(BTUH)
────────
0
-26,719
-13,125
-31,250
0
0
0
0
0
0
0
-57,854
────────
-128,948
-25.8
───────────────────
[a] Lotus 1-2-3 is a trademark of the Lotus Development Corporation,
Cambridge, Massachusetts.
4.25
TABLE 4.4.
Sample ASEAM Systems Output Report
ASEAM2 Report: SYS-BC-VAVR
File Name: DEMO
System Name: VAV Reheat
System Energy Requirements (Plant Loads)
Date: 04-07-1987
System Type: VAVR
Sample Single Run Calculation
Month Cycle
<------ System Loads on Plant ------>
Jan
Occup
Preheat
Humidity
Cooling
Heating
Baseboard
Bin
Bin
Oper
Energy
Energy
Energy
Energy
Energy
Midpt Hours
Hours
KBTUH
KBTUH
KBTUH
KBTUH
KBTUH
───────────────────────────────────────────────────────────────────────────
17.5
15.7
15.7
0.0
26.1
0.0
108.9
0.0
12.5
17.9
17.9
0.0
28.0
0.0
118.0
0.0
7.5
2.5
2.5
0.0
26.6
0.0
127.1
0.0
2.5
0.7
0.7
0.0
27.2
0.0
136.2
0.0
Month Cycle
<------ System Loads on Plant ------>
Jan
Occup
Preheat
Humidity
Cooling
Heating
Baseboard
Bin
Bin
Oper
Energy
Energy
Energy
Energy
Energy
Midpt Hours
Hours
KBTUH
KBTUH
KBTUH
KBTUH
KBTUH
───────────────────────────────────────────────────────────────────────────
57.5
2.5
2.5
0.0
0.0
0.0
3.7
0.0
52.5
10.4
10.4
0.0
0.0
0.0
33.0
0.0
47.5
11.1
11.1
0.0
0.0
0.0
50.1
0.0
42.5
13.2
13.2
0.0
4.9
0.0
58.6
0.0
37.5
31.4
31.4
0.0
17.6
0.0
69.5
0.0
32.5
33.2
33.2
0.0
19.8
0.0
79.1
0.0
27.5
35.4
35.4
0.0
22.0
0.0
88.3
0.0
22.5
27.9
27.9
0.0
23.1
0.0
97.4
0.0
17.5
9.3
9.3
0.0
29.4
0.0
106.6
0.0
12.5
8.6
8.6
0.0
31.0
0.0
115.8
0.0
7.5
8.6
8.6
0.0
31.7
0.0
124.9
0.0
2.5
7.9
7.9
0.0
31.9
0.0
134.1
0.0
-2.5
0.7
0.7
0.0
31.8
0.0
143.3
0.0
Month Cycle
<------ System Loads on Plant ------>
Jan
Occup
Preheat
Humidity
Cooling
Heating
Baseboard
Bin
Bin
Oper
Energy
Energy
Energy
Energy
Energy
Midpt Hours
Hours
KBTUH
KBTUH
KBTUH
KBTUH
KBTUH
───────────────────────────────────────────────────────────────────────────
67.5
4.6
4.6
0.0
0.0
0.0
0.0
0.0
62.5
5.4
5.4
0.0
0.0
0.0
0.0
0.0
57.5
5.7
5.7
0.0
0.0
0.0
2.0
0.0
52.5
14.3
14.3
0.0
0.0
0.0
28.1
0.0
47.5
15.4
15.4
0.0
0.0
0.0
47.2
0.0
42.5
23.9
23.9
0.0
20.8
0.0
55.2
0.0
37.5
70.7
70.7
0.0
17.6
0.0
64.6
0.0
32.5
59.3
59.3
0.0
14.7
0.0
75.3
0.0
27.5
19.3
19.3
0.0
22.0
0.0
84.4
0.0
4.26
TABLE 4.5.
Sample of Tabular ASEAM Report
Report
Month
Bin
Bin
Oper
Heating
Plant
Part Load
Boiler
Fuel
Cyc
Temp Hours
Hours
Load
Load
Ratio
Effic
Therms
─────────────────────────────────────────────────────────────────────────────────
─
PBLR
1
1
67.5
6.0
1.5
58,664
58,664
0.250
58.73
0.990
PBLR
1
1
62.5
14.0
4.0
70,486
70,486
0.289
60.64
1.160
PBLR
1
1
57.5
9.0
3.0
82,308
32,308
0.338
62.99
1.300
PBLR
1
1
52.5
5.0
1.9
94,129
94,129
0.386
62.90
1.450
PBLR
1
1
47.5
25.0
10.8
105,951 105,951
0.435
66.92
1.580
PBLR
1
1
42.5
30.0
14.5
117,773 117,773
0.484
68.52
1.710
PBLR
1
1
37.5
45.0
23.9
129,595 129.595
0.532
69.99
1.850
PBLR
1
1
32.5
65.0
37.7
141,417 141,417
0.581
71.33
1.980
PBLR
1
1
27.5
24.0
15.1
153,239 153,239
0.629
72.48
2.110
PBLR
1
1
22.5
10.0
6.7
165,060 165,060
0.678
73.40
2.240
PBLR
1
1
17.5
14.0
10.1
176,882 176,882
0.727
74.18
2.380
PBLR
1
1
12.5
1.0
0.7
188,704 135,704
0.775
74.77
2.520
PBLR
1
2
62.5
7.0
1.9
66,418
66,418
0.273
60.49
1.090
PBLR
1
2
57.5
9.0
2.8
78,240
78,240
0.321
62.47
1.250
PBLR
1
2
52.5
12.0
4.4
90,062
90,062
0.370
64.38
1.390
PBLR
1
2
47.5
29.0
12.1
101,884 101,884
0.418
66.39
1.530
PBLR
1
2
42.5
51.0
23.8
113,706 113,706
0.467
68.15
1.660
PBLR
1
2
37.5
82.0
42.3
125,527 125,527
0.516
69.61
1.800
PBLR
1
2
32.5
23.0
12.9
137,349 137,349
0.564
70.97
1.930
PBLR
1
2
27.5
11.0
6.7
149,171 149,171
0.613
72.09
2.060
PBLR
1
3
77.5
3.0
0.7
27,121
27,121
0.250
59.38
0.450
PBLR
1
3
72.5
8.0
2.0
39,065
39,065
0.250
59.43
0.650
Table 4.6 is a sample of ASEAM calculations, which can be reviewed or
spot checked by the user. Reviewing this type of information on a regular
basis would be impractical. However, if the user is having a problem with a
particular simulation, this is one approach to identifying the problem.
Alternately, the user can review the graphical output, such as that shown in
Figure 4.1. The program will display every calculated condition for loads,
systems, and plants. In this example, a five-zone VAV reheat system is
shown. The outside air temperature is 77.5 deg., and the calculation
represents the 7.1 occupied hours when this condition occurs in September.
The three sets of numbers in the air duct represent the dry bulb temperature,
the humidity ratio, and the enthalpy of the air. In this example, 20%
outside air is mixed with return air, the air is cooled to 55 deg. F, and no
reheat is required. Note the increase in air temperature when the air passes
through the supply fan.
Thus, the output reports of ASEAM permit a range of output review
capabilities, which can be as simple as a one-page summary or as complex as a
listing of nearly every calculation the program has made.
4.27
TABLE 4.6.
Load
Wall
Wall
Wall
Wall
Calc
Cond
Cond
Cond
Cond
Z#
1
1
1
1
M#
1
1
1
1
S#
1
1
1
1
Load
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
Z#
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
M#
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
S# HR
1 1
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
1 18
1 19
1 20
1 21
1 22
1 23
1 24
Load
Roof
Roof
Roof
Roof
Calc
Cond
Cond
Cond
Cond
Z#
1
1
1
1
M#
1
1
1
1
S#
1
1
1
1
Load
Roof
Roof
Roof
Roof
Roof
Roof
Roof
Roof
Roof
Roof
Roof
Roof
Roof
Roof
Roof
Roof
Roof
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
CLTD
Z#
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
M#
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
S# HR
1 1
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
1 11
1 12
1 13
1 14
1 15
1 16
1 17
Sample of ASEAM Calculation
U-FCT
(0.100)
(0.100)
(0.100)
(0.100)
SOL#
1.2
2.2
3.2
4.2
5.2
6.2
7.2
8.2
9.2
10.2
11.2
12.2
13.2
14.2
15.2
16.2
17.2
18.2
19.2
20.2
21.2
22.2
23.2
24.2
U-FCT
(0.100)
(0.100)
(0.100)
(0.100)
AREA
( 700)
( 700)
( 700)
( 700)
OAT
(42.5
( 2.5
(42.5
( 2.5
-
SPC T
68.0)=
68.0)=
60.0)=
60.0)=
U-FCT
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
(0.100)
AREA
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
(700)
CLTD
(18.6
(16.6
(14.6
(12.6
(10.6
( 8.8
( 7.8
( 6.8
( 6.0
( 6.2
( 7.4
( 9.6
(12.8
(16.8
(20.8
(24.6
(27.4
(29.0
(29.0
(28.6
(26.8
(25.6
(23.6
(21.4
AREA
(900)
(900)
(900)
(900)
OAT
(42.5
( 2.5
(42.5
( 2.5
-
SOL# U-FCT
1.2 (0.100)
2.2 (0.100)
3.2 (0.100)
4.2 (0.100)
5.2 (0.100)
6.2 (0.100)
7.2 (0.100)
8.2 (0.100)
9.2 (0.100)
10.2 (0.100)
11.2 (0.100)
12.2 (0.100)
13.2 (0.100)
14.2 (0.100)
15.2 (0.100)
16.2 (0.100)
17.2 (0.100)
AREA
(900)
(900)
(900)
(900)
(900)
(900)
(900)
(900)
(900)
(900)
(900)
(900)
(900)
(900)
(900)
(900)
(900)
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
LMC
11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 -
SPC T
68.0)=
68.0)=
60.0)=
60.0)=
CLTD
(31.2
(27.0
(22.2
(18.4
(15.4
(12.4
( 9.6
( 7.8
( 7.2
( 8.6
(12.0
(17.2
(23.4
(30.4
(37.2
(43.2
(48.8
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
WALL LOAD
-1,785
-4,585
-1,225
-4,025
LMC
-19
-19
-19
-19
-19
-19
-19
-19
-19
-19
-19
-19
-19
-19
-19
-19
-19
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
COL C CLTD LD
(0.83)= 1,313
(0.83)= 1,197
(0.83)= 1,081
(0.83)=
965
(0.83)=
848
(0.83)=
744
(0.83)=
686
(0.83)=
628
(0.83)=
581
(0.83)=
593
(0.83)=
662
(0.83)=
790
(0.83)=
976
(0.83)= 1,208
(0.83)= 1,441
(0.83)= 1,661
(0.83)= 1,824
(0.83)= 1,917
(0.83)= 1,917
(0.83)= 1,894
(0.83)= 1,790
(0.83)= 1,720
(0.83)= 1,604
(0.83)= 1,476
BIN LOAD
-2,295
-5,895
-1,575
-5,175
-
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
7)
ACCUM WALL
-1,785
-4,585
-1,225
-4,025
ACC LD
1,313
1,197
1,081
965
848
744
686
623
581
593
662
790
976
1,208
1,441
1,661
1,824
1,917
1,917
1,894
1,790
1,720
1,604
1,476
ACCUM LOAD
-2,295
-5,895
-1,575
-5,175
COL C CLTD LD ACC LD
(1.00)=
468 1,782
(1.00)=
90 1,287
(1.00)=
-342
739
(1.00)=
-684
281
(1.00)=
-954
-105
(1.00)= -1,224
-480
(1.00)= -1,476
-790
(1.00)= -1,638 -1,010
(1.00)= -1,692 -1,111
(1.00)= -1,566
-974
(1.00)= -1,260
-598
(1.00)=
-793
-3
(1.00)=
-235
741
(1.00)=
395 1,604
(1.00)= 1,007 2,448
(1.00)= 1,547 3,209
(1.00)= 2,052 3,876
Roof CLTD
Roof CLTD
Roof CLTD
1
1
1
1
1
1
1 18
1 19
1 20
18.2 (0.100) (900) (52.4 + -19 - 7) (1.00)=
19.2 (0.100) (900) (54.0 + -19 - 7) (1.00)=
20.2 (0.100) (900) (53.4 + -19 - 7) (1.00)=
4.28
2,376
2,520
2,466
4,293
4,437
4,360
4.6.2
Calculating Payback and Using Life Cycle Costing
The simplest representation of payback is the simple payback period, the
installed capital cost divided by the value of energy saved per year.
However, the payback period is affected by many other factors such as taxes,
the time value of money, maintenance, and energy escalation rates. Life
cycle costing programs are used to account for these factors.
Two separate life cycle costing programs have been integrated into
ASEAM:
o
Federal Building Life Cycle Cost Program (FBLCC)
o
National Bureau of Standards Life Cycle Cost Program (NBSLCC).
The first program has been designed specifically for federal buildings and
incorporates financial assumptions appropriate for federal facilities. The
second program should be used for non-federal buildings. The input data
files for these programs are created in a similar fashion to the load,
system, and plant input files. The two economic programs require different
inputs and their files cannot be interchanged. Both economic analyses have
been integrated into ASEAM such that they can be executed in conjunction with
the energy analysis.
4.29
4.7
LIMITATIONS OF SIMULATIONS
A building simulation is a representation of how a real building
functions. Simulations are effective tools for use in the building design
and retrofit process. However, they must be applied and interpreted with
care. In most cases, accurate energy prediction is possible; however, there
are limitations that can lead to inaccurate results. The following is a list
of some of these limitations.
4.7.1
General Limitations
Not all building parameters can be firmly specified. Some parameters
can be specified only on the basis of engineering judgment or experience with
the building. For example, a lighting system designed at 1.9 watts/ft2
instead of 2.5 watts/ft2 is a parameter that can be precisely determined.
The fact that the lights are operated 10 hours per day, 5 days per week, is
an educated guess. Experience may show that an automated boiler blowdown
system improves boiler efficiency by, say, 4%. The actual savings in a
particular application may vary. This specification is based on engineering
judgment and has nothing to do with the accuracy of the simulation.
Building operational schedules and setpoints have a significant impact
on energy usage but are seldom precisely known. Furthermore, future
conditions must be assumed, although they may vary substantially.
The impact of the human factor on energy consumption cannot be
over-emphasized. The energy usage of two identical buildings has been found
to vary by as much as 40% to 50%. In one instance, the cleaning crew was
assumed to use minimal lighting when cleaning the building. In practice, the
crew turned on every light in the building when it began cleaning and turned
the lights off in completed areas. The result was that building lighting was
operated 75% more than anticipated. This human factor affected lighting
power consumption, cooling loads, and relamping intervals. In another case,
six cooks were asked to prepare three meals per day for seven days; the meals
and the electric ranges were identical. Energy use varied by as much as
3.4 kWh/day to 5.1 kWh/day. Thus, the practices of the cooks are probably
more significant than the efficiency of a given electric range.
4.7.2
Loads Limitations
Climate can vary +/- 15% from year to year. The local climate can also
vary with respect to the nearest available meteorological station. Because
of the effect of climate on building energy use, it is important to use
typical meteorological year (TMY) weather data to evaluate the long-term
performance of energy conservation measures.
4.30
The thermal conductivity of exterior walls and ceilings is often
difficult to determine for existing buildings. Shortcuts or variances with
"as-built" construction document specifications for insulation are frequent.
Physical inspection, judgment, and/or testing is needed to select the
appropriate levels. When the space temperature is set at 68 deg. F, the
simulation represents the entire zone as being heated to 68 deg. F. In the
building, the HVAC equipment maintains the thermostat at 68 deg. F. Thus the
simulation will not account for increased energy consumption as a result of
improper thermostat placement.
Most simulation models cannot account for internal temperature
variations that result from the location of supply ducts, interzonal heat
transfer, HVAC systems that compete with each other, return duct locations
that cause short cycling, and movable partitions that restrict air movement.
Furthermore, the thermostats may be adjusted to achieve minimal comfort
levels in the coolest or warmest spaces, thereby overheating or overcooling
other spaces.
One or two building employees may work nights or weekends. To
accommodate them, the fan, thermostat, and lighting schedules of a whole wing
of a building may be altered. The effect of space conditioning and lighting
energy needs would be significant.
Lights in glass vestibules may be assumed to be off during the day, when
in fact they are left on. The vestibule heater may be assumed to be set at
55 deg. F, but may actually run continually. Inner vestibule doors may be
blocked open; outer doors left open on mild days.
Some items are difficult to model or measure accurately. One of the
most significant is the amount of air exchange with the outdoors. While
default values are provided, they may be inappropriate to determine the
absolute energy requirements.
Internal heat gains generated by lights and other equipment have a large
impact on building loads. While the capacity of most of this equipment can
be estimated, the number of hours per day or week that the equipment operates
is often a guess. For this reason, the DOE and others are submetering
building energy use to develop empirical profiles of equipment usage.
4.7.3
Systems Limitations
The performance of most HVAC equipment will vary; five identical heat
pumps rated at a COP of 2.5 may, when tested individually, actually operate
at a COP of from 2.3 to 2.7.
A building simulation assumes a closed damper is, in fact, closed; in
reality, most air dampers leak. A damper that is 2% open may let in 8% to
10% outside air.
Most building simulations make no allowance for controls that are out of
calibration or linkages that are stuck or disconnected. This limitation can be
particularly severe for large and complex control systems because of the
increasing number of possible failures that may escape notice.
4.31
4.7.4
Plant Limitations
The simulation assumes equipment functions as designed. In one
instance, the manufacturer claimed a chiller used 25% of the rated power at
15% load. Upon investigation, the unit was found to draw 40% power at 15%
load.
HVAC systems and controls are often selected on a bid basis. The
equipment actually supplied will vary from design. For example, a building
may have a peak cooling load of 80 tons, and a chiller is specified by the
engineer at 100 tons. The low-bid manufacturer does not make a 100-ton
chiller and, instead, bids a 110-ton chiller. Furthermore, the compressor
unloading stops may be different than those simulated. Thus, the chiller
will have a completely different part-load performance curve than is assumed
in the simulation.
Chillers and boilers are typically cleaned annually. Their performance
gradually degrades from the day they start up until the day they are cleaned.
Oil burner nozzles may be changed annually, but they wear gradually over the
course of a heating season. Most building simulations do not account for
this.
4.8
THE FUTURE OF ENERGY SIMULATIONS
Present-day energy use simulation methods are based largely upon
thermodynamics and engineering theory of how buildings should operate.
Before any simulation is relied upon, every attempt should be made to check
the simulation's accuracy by comparing its results with available measured
data. As more empirical data on building energy performance are obtained and
studied, theoretical approaches should be tested and refined to converge with
and apply additional empirical evidence.
It may also be practical in the near future to apply empirically based
models or sophisticated expert systems to the determination of building
energy flows and conservation potentials. These models may be based upon a
set of diagnostic tests for a particular building, experimental results, or
large databases containing the measured performance of similar buildings and
energy conservation measures. As additional measured data are made available
to the research community, the state-of-the-art of building energy simulation
will advance. When coupled with the increasing sophistication of desktop
computers and users, these data may encourage a new era of energy use
analysis based upon measurements, thereby removing some of the present
uncertainties associated with key assumptions of the theoretical approaches
now in use.
4.32
5.0
REFERENCES
American Society of Heating, Refrigerating, and Air-Conditioning Engineers,
Inc. (ASHRAE). 1986. A Bibliography of Available Computer Programs in the
Area of Heating, Ventilating, Air Conditioning, and Refrigeration. 1791
Tullie Circle, N.E., Atlanta, Georgia.
Energy Information Administration (EIA). 1987. Residential Energy Consumption Survey: Consumption and Expenditures, April 1984 through March 1985.
DOE/EIA-0321(84), Energy Information Administration, Office of Energy
Markets and End Use, U.S. Department of Energy, Washington, D.C.
Energy Information Administration (EIA). 1988. Nonresidential Buildings
Energy Consumption Survey: Characteristics of Commercial Buildings, 1986.
DOE/EIA-0246(86), Energy Information Administration, Office of Energy
Markets and End Use, U.S. Department of Energy, Washington, D.C.
Energy
Energy
tures,
Energy
Information Administration (EIA). 1989. Nonresidential Buildings
Consumption Survey: Commercial Buildings Consumption and Expendi1986. DOE/EIA-0318(86), Energy Information Administration, Office of
Markets and End Use, U.S. Department of Energy, Washington, D.C.
Ruegg, R. T. 1980. Life-Cycle Costing Manual for the Federal Energy
Management Programs. NBS Handbook 135, National Bureau of Standards, U.S.
Department of Commerce, Washington, D.C.
U.S. Department of Energy (DOE).
DOE/CE-0115/4, Washington, D.C.
1983.
Federal Ten Year Buildings Plan.
U.S. Department of Energy (DOE). 1988. Energy Conservation Multi-Year
Plan, 1990-1994. U.S. Department of Energy, Office of Conservation,
Washington, D.C.
U.S. Department of Energy (DOE).
DOE/BET-89/1, Washington, D.C.
1989.
Buildings Energy Technology.
U.S. General Services Administration (GSA). 1988a. Summary Report of Real
Property Leased by the United States Throughout the World as of September,
1987. General Services Administration, Public Buildings SErvice,
Washington, D.C.
U.S. General Services Administration (GSA). 1988b. Summary Report of Real
Property Owned by the United States Throughout the World as of September 30,
1987. General Services Administration, Public Buildings Service,
Washington, D.C.
5.1 NEXTRECORD
APPENDIX A
INFORMATION TO BE GATHERED DURING AUDITS
Appendix A consists of two tables containing information to be
gathered during audits. Table A.1 contains information that should be
gathered during the preliminary audit of a building and is divided into the
following four categories: overall facility information, information on
major energy-using systems/equipment, the types of systems/equipment
contained in the building, and energy billing data. Table A.2 contains
information that should be gathered during the building audit and is divided
into the following five data categories: building envelope/shell, HVAC
systems, lighting and electrical systems, central plant systems, and
weather. A discussion of these audits is contained in Chapter 3.
TABLE A.1.
Information to be Gathered During Preliminary Audit
OVERALL FACILITY INFORMATION
@
Floor area of building (ft2) and of different
functional parts (e.g. offices, warehouses,
etc.)
@
Volume of building (ft3) and of different
functional part
@
Age of building (date of construction,
remodels, additions and descriptions of
changes
@
Blueprints of architectural, mechanical, and
electrical systems
@
Lighting types, amount, and operating
schedule (interior and exterior)
@
Insulation levels (type, amount, location)
@
Building operating hours (seasonal, weekly,
holiday changes)
@
Occupancy (seasonal, daily, weekly changes)
@
Any planned changes to the building
MAJOR ENERGY-USING SYSTEMS/EQUIPMENT INFORMATION
@
Type, size, design, specs, age, etc.
TABLE A.1.
@
(contd)
Fuel used for heating, cooling, and water
heating
@
Location noted on blueprints
@
Operating hours and schedules
@
Control schemes or equipment used
TYPES OF SYSTEMS/EQUIPMENT TO BE CONSIDERED
@
HVAC distribution systems
@
Heating systems (boiler, furnace, heat pump)
@
Cooling systems (chiller, cooling tower, air
conditioner)
@
Water heater
@
Freezer/refrigeration compressors
@
Auxiliary Equipment (pumps, fans, etc.)
@
Other systems (food service, laundry,
computers)
ENERGY BILLING DATA
@
For all types of energy used (electricity,
natural gas, oil, steam, etc.)
@
For as many years as possible
@
In as much detail as possible
@
Per unit cost (including any changes in cost
per season, time-of-day, etc.)
@
Demand changes
A.2 NEXTRECORD
TABLE A.2.
Information to be Gathered During Building Audit
BUILDING ENVELOPE/SHELL
@
Floor area
@
Number of zones and zone identification
@
Area by zone
@
Thermostat schedules and setpoints
@
Occupancy schedules
@
Sensible and latent heat gain from people
@
Exterior walls (materials of construction)
@
Roof
@
Windows (type, area, weatherstripping, etc.)
@
Shading and overhangs
@
Doors (type, area, etc.)
@
Underground walls
@
Miscellaneous conduction (e.g., freezer
walls)
@
Insulation (type, location, area, etc.)
@
Infiltration
HVAC DATA
The data required is for both distribution
systems and unitary equipment (e.g. heat
pumps).
@
System label and type
@
Zone assignments to systems
@
Heat source for systems (plant type)
@
Cooling source for systems (plant type)
A.3NEXTRECORD
TABLE A.2.
(contd)
@
System availability and schedules
@
System specific information as required such
as:
- deck temperatures
- controls
- outside air and damper control
- humidification
- preheat and reheat
- fan power and flow rate
- loop temperature
- backup heating
@
Unitary system information as required such
as:
- design COPs for air conditioners and heat pumps
- efficiency and parasitic losses for furnaces
- unloading ratios for DX cooling systems
LIGHTING AND ELECTRICAL SYSTEMS
Most of this information is per zone
@
Lighting levels (watts/ft2, footcandles)
@
Control scheme for lights (switches,
schedules)
@
Location of fixtures
@
Type and size of lights (fluorescent,
incandescent, etc.)
@
Motors (Type, HP, amperage, etc.)
@
Location and condition of transformers and
switch boxes
@
Power factor of building (if applicable)
CENTRAL PLANT SYSTEMS
This includes specifications of the primary
energy-using systems such as boilers,
chillers, cooling towers, circulating pumps,
and water heating systems.
A.4 NEXTRECORD
TABLE A.2.
@
(contd)
Boiler specifications such as:
- fuel usage and cost
- number of units
- capacity
- design efficiency
- controls
- minimum part load ratio
- boiler pump kW
- standby/parasitic losses
@
Cooling plant specifications such as:
- fuel usage and cost
- number of units
- capacity
- design COPs
- controls
- unloading and part load ratios
- water temperatures and flow rates
- load management system specifications
- pump kW's
@
Cooling tower specifications such as:
- heat rejection capacity
- number of cells
- fan kW per cell
- water temperatures and flow rates
- pump kW's
- approach temperature
- controls
@
Domestic water specifications such as:
- fuel usage and cost
- heating capacity
- average usage
- inlet and supply temperatures
- circulation pump kW and scheduling
- design efficiency
- standby losses
WEATHER DATA
The auditor should select an available
weather station which most closely
corresponds to the location of the building
being analyzed.
@
Air temperature (average daily and monthly)
A.5 NEXTRECORD
@
Relative humidity or humidity ratio
@
Wind speed
@
Wind direction
@
Insolation or cloud cover
@
Average heating and cooling degree days (if
average temperatures are not available).
A.6 NEXTRECORD
APPENDIX B
SIMULATION MODEL INPUTS FOR ASEAM VERSION 2.1
Appendix B is an abbreviated listing of the input variables for ASEAM
Version 2.1. The actual entry of the data into the model is done with
numerous "user friendly" screens. Each screen provides a menu of input
options and available defaults. The input forms are divided into the
following four data types: building load data (loads), HVAC systems data
(systems), plant equipment data (plant), and economics data (Federal Building
Life Cycle Costing - FBLCC).
B.1
ASEAM LOADS INPUT FORMS (ABBREVIATED)
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
Building File Name
Building Name
Project Number
Building Address
Building Type
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
Bldg/Project
(The following two screens apply to the entire building)
Shading
Shading
Shading
Shading
Shading
Shading
Shading
Shading
Shading
Shading
Shading
Shading
Shading
Shading
Shading
Shading
Window Model Name (or 'NA')
Window Width
Window Height
Overhang Depth
Top of Window to Overhang
Overhang extension beyond left edge of window
Overhang extension beyond right edge of window
Depth of vert projection at end of overhang
Depth of left fin
Left fin extension above top of window
Distance from left edge of window to left fin
Dist from left fin bottom to bottom of window
Depth of right fin
Right fin extension above top of window
Dist from right edge of window to right fin
Dist from right fin bottom to bottom of window
Month
Month
Month
Month
Month
Month
Month
Month
Month
Month
Month
Month
Month
Month
January
February
March
April
May
June
July
August
September
October
November
December
Sch
Sch
Sch
Sch
Sch
Sch
Sch
Sch
Sch
Sch
Sch
Sch
Sch
B.2
Zone
Zone
Zone
Zone
Zone
Zone
Zone
Zone
Zone label
Zone function (Opt)
Zone area
Zone volume
(or) Floor to ceiling height
Summer occupied temperature setpoint
Winter occupied temperature setpoint
Winter unoccupied temperature setpoint
Lighting
Lighting
Lighting
Lighting
Lighting
Lighting
Lighting
Lighting
Lighting
Lighting
Lighting
Lighting
Lighting
Lighting
Function name (or 'NA')
Average function area (ft)
Installed watts/ft
(times) Percent of function area
(or) Total installed watts
Daylighting (Y/N)
Controlite filename (if appl)
Lighting system type (Opt)
Percent light heat to space (%)
'A' classification
'B' classification
Diversity Factor Occupied
Diversity Factor Unoccupied
Monthly Diversity Factor Table #
Daylighting
Daylighting
Daylighting
Daylighting
Daylighting
Daylighting
Daylighting
Daylighting
Daylighting
Daylighting
Daylighting
Daylighting
Daylighting
Daylighting
Function name (or 'NA')
Window orientation (N,NW,etc)
Ground reflectance (%)
Typical room window area (ft2)
Glass visible transmittance (%) Room depth from window (ft)
Room length (ft)
Ceiling height (ft)
Wall reflectance (%)
Present footcandles in space
Design footcandles for space
Sensor location
Percent of lights controlled
Control type ('D'im or 'S'tep)
_ _
_
Dayl-Controls Function name (or 'NA')
Dayl-Controls For Dimming Control Only
Minimum FC maintained by lights
Dayl-Controls
% of total power at min FC (%)
Dayl-Controls
Dayl-Controls For Stepped Control Only
Number of Steps (max=4)
Dayl-Controls
Step 1 artificial FC
Dayl-Controls
Step 1 lighting watts
Dayl-Controls
Step 2 artificial FC
Dayl-Controls
Step 2 lighting watts
Dayl-Controls
Step 3 artificial FC
Dayl-Controls
Step 3 lighting watts
Dayl-Controls
Step 4 artificial FC
Dayl-Controls
Step 4 lighting watts
Dayl-Controls
People
People
People
People
Number of people in zone
(or) Square feet per person
BTUH load per person
Diversity Factor Occupied -
B.3
Sensible
Unoccupied
ASEAM LOADS INPUT FORMS (ABBREVIATED)
Misc
Misc
Misc
Misc
Misc
Misc
Misc
Misc
Elect
Elect
Elect
Elect
Elect
Elect
Elect
Elect
Electric equipment name (or 'NA')
Installed watts/ft
(times) Percent of zone area
(or) Total installed watts
Hooded (Y/N)
Diversity Factor Occupied
Diversity Factor Unoccupied
Monthly Diversity Factor Table Number
Misc
Misc
Misc
Misc
Misc
Misc
Misc
Misc
Sens
Sens
Sens
Sens
Sens
Sens
Sens
Sens
Load source name (or 'NA')
Installed BTUH/ft
(times) Percent of zone area
(or) Total installed BTUH
Hooded (Y/N)
Diversity Factor Occupied
Diversity Factor Unoccupied
Monthly Diversity Factor Table Number
Zone #
Wall
Wall
Wall
Wall
Wall
Wall
Name (or 'NA')
Wall Orient (N,NE,etc)
Area (ft)
U-Factor (BTUH/ft-)
Wall Construction Group
Color Correction
Roof
Roof
Roof
Roof
Roof
Roof
Name (or 'NA')
Area (ft)
U-Factor (BTUH/ft-)
Roof Construction Code
Color Correction
Susp Ceil Plenum (Y/N)
Window
Window
Window
Window
Window
Window
Window
Window
Window
Window
Name (or 'NA')
Window orient (N,NE,etc
Fenestration area (ft)
Shading coefficient
U-Factor (BTUH/ft-)
Space mass code
Crack length (lin ft)
Leakage coefficient
Window shading model #
Percent window area
Door
Door
Door
Door
Door
Name (or 'NA')
Area (ft)
U-Factor (BTUH/ft-)
Crack length (lin ft)
Leakage coefficient
Infiltration
Infiltration
Occupied air change rate
Unoccupied air change rate
air changes per hour
air changes per hour
Mist
Mist
Mist
Mist
Misc
Name (or
Area (ft)
U-Factor
Reference
Reference
F)
F)
Conduct
Conduct
Conduct
Conduct
Conduct
'NA')
(BTUH/ft-)
temperature at design summer
temperature at design winter
B-4
ASEAM2 SYSTEMS INPUT FORM (ABBREVIATED)
Total number of systems
System #
System
1=DDMZ
9=BB
2=cVRH
lO=FURN
Zone
Number
Zone
Label
System Type
Label
3=VAVR
ll=UH
System
4=CBVAV
12=HV
Types
5=SZRH
6=FCU
13=WAC
Heating
Cooling
System #
NOTE - THE ZONE NUMBERS AND LABELS
(AS DEFINED IN LOADS INPUT)
WILL BE PRINTED HERE
B.5
l=WSHP
8=AAHP
Heating
ONLY
System #
Cooling
ONLY
System #.
System #
ASEAM2 SYSTEMS INPUT FORM (ABBREVIATED)
Heating coil plant type (Use Codes Below)
5=Furn
O=None l=Boiler 2=Elect Resist 3=Dist Heat 4=DB Chiller
Outside temperature above which heating is off
Heating available beginning month #
Heating available ending month #
Design heating coil discharge temperature
(DDMZ ONLY)
Discriminator Control (Y/N)
Outside temperature at maximum hot deck temperature (DDMZ ONLY)
(DDMZ ONLY)
Maximum hot deck temperature
Outside temperature at minimum hot deck temperature (DDMZ ONLY)
(DDMZ ONLY)
Minimum hot deck temperature
Cooling coil plant type (see codes below)
O=None l=DX 2=Centrifugal 3=Absorption 4=District Cooling
5=Double Bundle 6=Cooling Tower (WSHP only) 7=Reciprocating
Outside temperature below which cooling is off
Cooling available beginning month #
Cooling available ending month #
Design cooling coil discharge temperature
Discriminator control (Y/N)
Maximum cooling coil discharge temperature
Preheat coil plant type (Use Heating Codes 0 - 3)
Outside temperature above which preheat is off
Preheat available beginning month #
Preheat available ending month #
Design preheat coil discharge temperature
Humidification plant type (Use Heating Codes 0 - 3)
Outside temperature above which humidification is off
Humidification available beginning month #
Humidification available ending month #
Humidification available during unoccupied cycle (Y/N)
Minimum relative humidity maintained
Baseboard plant type (Use Heating Codes 0 - 3)
Outside temperature above which baseboard is off
Baseboard available beginning month #
Baseboard available ending month #
Baseboard control type (l=thermostatic 2=OA reset)
Percent of design heating load satisfied at design winter
Percent of design heating load satisfied at balance temp
Total supply fan power required (blank=default)
(or) Supply fan power per 1000 CFM
Supply fan temperature rise (blank=default)
Total return fan power required (blank=default)
(or) Return fan power per 1000 CFM
Return fan temperature rise (blank=default)
(VAV) Minimum percent of design air volume-when heating
(VAV) Air volume control method (l=Speed 2=Discharge 3=Inlet)
Occupied cycle fan control method (1=On Continuously 2=Cycles)
Unoccupied cycle fan control method (l=On Continuously 2=Cycles)
Outside air damper control method (see codes below)
3=Dry Bulb
l=No Outside Air 2=Fixed Dampers
Minimum percent outside air intake
Dry bulb switchover temperature
8.6 B.6
----
4=Enthalpy
ASEAM2 SYSTEMS INPUT FORM (ABBREVIATED)
System #
(Heat Pump and Window Air Conditioner only)
Zonal total cooling capacity method (l=User Entered 2=Autosized)
(if autosized) Percent of design total load satisfied
Zonal sensible cooling capacity method (l=User Entered 2=Autosized)
(if autosized) Percent of design sensible load satisfied
Design coefficient of performance
Outside temperature at minimum fluid loop temperature
Minimum fluid loop temperature
Outside temperature at maximum fluid loop temperature
Maximum fluid loop temperature
Zonal heating capacity method (l=User Entered 2=Autosized)
(if autosized) Percent of max heat pump load satisfied
AAHP backup heating source (l=Furnace 2=Electric Resistance)
Outside temperature below which backup heating is on
Zonal electric resistance backup heating capacity method
(l=Capacities Entered by Zone 2=Autosized)
(if autosized) Percent of design heating load satisfied
Design heating coefficient of performance
Furnace fuel source (see codes below)
l=Electric 2=Natural Gas 3=#2 Oil 4=#4 Oil 5=#6 Oil
Furnace capacity (blank=autosize)
(if autosized) Percent of design load satisfied
Furnace efficiency at design load
Losses as percent of design load (at design load)
Losses as percent of design load (at no load)
Pilot gas annual consumption
Zonal
(if
Zonal
(if
air volume method (l=User Entered 2=Autosized)
autosized) Percent of design default air flow
fan power method (l=User Entered 2=Autosized)
autosized) Percent of design default fan KW
DX total cooling capacity (blank=autosized)
(if autosized) Percent of design total load satisfied
Design coefficient of performance
Minimum unloading ratio (% of, capacity)
Minimum hot gas bypass ratio (% of capacity)
Condenser fan KW (blank=default)
Outside temperature below which condenser fan is off
Loads
Zone #
Zone Name
or Label
Zone
CFM
Zone
Fan KW
NOTE - THE ZONE NUMBER
AND LABEL FOR EACH ZONE
ASSIGNED TO THIS SYSTEM
IS PRINTED HERE
B.7
Zone Tot Zone Sen Zone HP
Clg Cap Clg Cap Htg Cap
(Tons) (Tons)
(Tons)
Zone HP
Bkup Htg
Cap (KW)
ASEAM2 PLANT INPUT FORMS
Fuel Type
Electricity
Natural Gas
#2 Oil
#4 Oil
#6 Oil
Dist Heating
Dist Cooling
Energy
Units
KWH
Therms
Gallons
Gallons
Gallons
MBTU
MBTU
Label for Miscellaneous
Energy Consumption
Fuel Code
1
2
3
4
5
Unit Cost
$ / Unit
(ABBREVIATED)
Conversion Factors (BTU/Unit)
Source
Site
Fuel Units
(See Codes Below)
Fuel Type
Natural Gas
Oil
Electricity
Dist Heating
Dist Cooling
B.8
Annual Consumption
in Energy Units
Energy Units
therms
gallons
KWH
MBTU
MBTU
ASEAM2 PLANT INPUT FORMS (ABBREVIATED)
Type 1
Type 2
tons
%
Centrifugal chiller cooling capacity (per chiller)
(or) Percent design load satisfied per chiller
Number of chillers of this capacity
Design coefficient of performance
Minimum unloading ratio (% of capacity)
Minimum part load ratio (% of capacity)
Load management/operation (l-always on 2=as needed)
Chilled water temperature at design load
Chilled water temperature at minimum load
Chilled water flow (blank=autosized)
Chilled water pump KW (blank=autosized)
Type 1
Type 2
tons
%
Absorption chiller cooling capacity (per chiller)
(or) Percent design load satisfied per chiller
Number of chillers of this capacity
Heat input energy source (l=Boiler 2=Dist Heat)
Design coefficient of performance
Minimum part load ratio (% of capacity)
Number of absorption stages
Load management/operation (l=always on 2=as needed)
Chilled water temperature at design load
Chilled water temperature at minimum load
Chilled water flow (blank=autosized)
Chilled water pump KW (blank=autosized)
F
F
gpm
Kw
Type 1
Type 2
tons
%
Double Bundle chiller cooling capacity (per chiller)
(or) Percent design load satisfied per chiller
Number of chillers of this capacity
Design coefficient of performance
Minimum unloading ratio (% of cap - clg mode)
Minimum unloading ratio (% of cap - htg mode)
Minimum part load ratio (% of capacity)
Load management/operation (l=always on 2=as needed)
Chilled water temperature at design load
Chilled water temperature at minimum load
Chilled water flow (blank=autosized)
Chilled water pump KW (blank=autosized)
Design heat recovery temperature
2=Dist Htg)
Heat recovery backup (l=Boiler
Type 1
Reciprocating chiller cooling capacity (per chiller)
(or) Percent design load satisfied per chiller
Number of chillers of this capacity
Design coefficient of performance
Minimum unloading ratio (% of capacity)
Minimum part load ratio (% of capacity)
Load management/operation (l=always on 2=as needed)
Chilled water temperature at design load
Chilled water temperature at minimum load
Chilled water flow (blank=autosized)
Chilled water pump KW (blank=autosized)
B.9
Type 2
ASEAM2 PLANT INPUT FORMS (ABBREVIATED)
Cooling tower total heat rejection capacity
(or) Percent of design heat rejection load satisfied
Number of tower cells (blank=autosized)
Fan KW per cell (blank=autosized)
Number of fan speeds (1 or 2)
Approach temperature
Condenser water temperature at design load
Condenser water temperature at minimum load
Condenser water flow rate (blank=autosized)
Condenser water pump KW (blank=autosized)
DHW Energy Source (O=None l=Elec 2=Gas 3=Oil 4=Blr
(if oil) Oil Type (2 or 4 or 6)
(if gas) Annual pilot consumption
Domestic Hot Water Heating Capacity (blank=autosized)
(if autosized) Peak hourly DHW usage
Average hourly DHW usage - occupied cycle
Average hourly DHW usage - unoccupied cycle
Domestic hot water supply temperature
DHW inlet temperature - design summer
DHW inlet temperature - design winter
Circulating pump KW - occupied cycle
Circulating pump KW - unoccupied cycle
Design DHW heating efficiency
DHW losses - occupied cycle
DHW losses - unoccupied cycle
Boiler Energy Source (l=Elect 2=Nat Gas 3=Oil)
(if oil) Oil type (2 or 4 or 6)
(if gas) Annual pilot consumption
Boiler heating capacity (per boiler)
(or) % max heating load satisfied (per boiler)
Number of boilers with this capacity
Load management/operation (l=always on 2=as needed)
2=calc)
Boiler efficiency method (l=user entered
Design boiler efficiency (if user entered)
(if calc) Combustion air temperature
(if calc) Stack temperature
(if calc) Air-Fuel ratio
Minimum part load operating ratio (% of capacity)
Boiler pump KW (blank=autosized)
Boiler losses - percent of capacity
Boiler losses - percent of load
B.10
5=Dist)
FBLCC Input Forms
PROJECT INFORMATION
Project
Title:
LCC Analysis Type
1 = Energy Conservation or Renewable Energy Projects (NBS 135) 2 = Non-Energy Related Projects (OMB Circular A-94)
Study Period (Years)
Occupancy Year (e.g. 1987)
DOE Region (1-11)
Building Type
1 = Residental 2 = Commercial 3 = Industrial
-
CAPITAL COMPONENTS DATA
Capital Component
(repeat for each capital component)
Component #
Component Name (or 'NA')
Initial Cost of Component (dollars)
Initial Conservation-Related Cost
Expected Component Life (Years) - Use '999' for Land
Average Escalation Rate During Planning/Construction Period
Average Escalation Rate During Occupancy
Resale Value Factor (Percent of Initial Cost)
COST PHASING SCHEDULE BY YEAR OF PLANNING/CONSTRUCTION PERIOD AND AT OCCUPANCY
Capital Component
(repeat for each capital
Component #
Enter Percentage of Cost for Each Year
( 1987 )
Planning/Construction Year 1
Planning/Construction Year 2
( 1988 )
At Occupancy
( 1989 )
component)
%
%
100.00
REPLACEMENTS TO CAPITAL COMPONENTS
Capital Component
Component #
(repeat for each capital
component)
Replacements to Capital Component
B.11
FBLCC Input Forms
OPERATING AND MAINTENANCE COSTS
Annually Recurring Costs
Annual Recurring Cost (Base-Year Dollars)
Average Annual Rate of Increase (%)
Non-Annually Recurring Costs
Number of Non-Annually Recurring Costs
Average Annual Rate of Increase (%)
Energy Type Code
l=Electricity
2=Distillate Fuel Oil
3=Residual Fuel Oil
4=Natural Gas
S=Liquified Petroleum Gas (LPG) 6 = Coal
Annual Consumption (MBTU)
Price per MBTU (Use F8 for DOE default)
Demand (or other) Charge
Price Escalation Method
1 = User Entered
2 = Defaulted
Average Annual Rate of Increase (%)
During Plan/Construction
-
--------- --------- ---------
ENERGY ESCALATION
(repeat for each fuel type)
Fuel Type #
Number of Discrete Time Intervals
# Dur Annual
Yrs Rate %
------------
# Dur Annual
Yrs Rate %
------------
# Dur Annual
Yrs Rate %
------------
B.12
# Dur Annual
Yrs Rate %
------------
# Dur Annual
Yrs Rate %
------------
APPENDIX C
PARAMETRIC INPUT AND OUTPUT VARIABLE LIST FOR ASEAM VERSION 2.1
Appendix C is a listing of the input variables that can be selected to
be changed in a parametric simulation using ASEAM Version 2.1. Up to 20 of
these input variables can be changed for parametric run. Also included in
Appendix C is a listing of the output variables that can be selected to be
determined using the parametric program. Again, up to 20 output variables
can be selected for parametric run.
C.1
Parametric Input Variable List
Input
Variable Variable Description
Notes Entry Remarks
Number
of Variable
Number Type
Type
==================3==========================================================
Loads
Orientation Adjustment
Loads
Weather Data Type
Loads
Weather Data Filename
Loads
Solar Data Filename
Loads
Starting Hour for Occupancy
Loads
Loads
Loads
Occupied Hours/Day
Summer Stat Start Month #
Summer Stat Ending Month #
NOT ASSIGNED
NOT ASSIGNED
Loads
Loads
Loads
Summer Stat Setpoint
Winter Stat Setpoint (OCC)
Winter Stat Setpoint (UNOCC)
NOT ASSIGNED
Wall U-Factor
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
NOT ASSIGNED
Roof U-Factor
NOT ASSIGNED
Window U-Factor
Window Shading Coef
N
Window Leak Coefficient
Window Shading Model #
NOT ASSIGNED
Daylighting Glass Transmittance
Daylighting Wall Reflectance
Daylighting Present FC
Daylighting Design FC
Daylighting Sensor Location
Daylighting Control Type
NOT ASSIGNED
NOT ASSIGNED
Daylighting Min FC Maintained
Daylighting Min % Power at Min FC
NOT ASSIGNED
NOT ASSIGNED
Div
Div
Div
Div
Factor
Factor
Factor
Factor
-
People
Lights
Lights
Lights
N
(OCC)
1 (OCC)
2 (OCC)
3 (OCC)
C.2
N (to 100)
Loads
Div Factor - Lights 4 (OCC)
Loads
Loads
Loads
Loads
Loads
Div
Div
Div
Div
Div
Factor
Factor
Factor
Factor
Factor
-
Equip 1 (OCC)
Equip 2 (OCC)
Misc Sens 1 (OCC)
Misc Sens 2 (OCC)
People (UNOCC)
Loads
Loads
Loads
Loads
Loads
Div
Div
Div
Div
Div
Factor
Factor
Factor
Factor
Factor
-
Lights 1 (UNOCC)
Lights 2 (UNOCC)
Lights 3 (UNOCC)
Lights 4 (UNOCC)
Equip 1 (UNOCC)
Loads
Loads
Loads
Div Factor - Equip 2 (UNOCC)
Div Factor - Mist Sens 1 (UNDCC)
Div Factor - Mist Sens 2 (UNOCC)
NOT ASSIGNED
Door U-Factor
N (to 100)
Door Leak Coef
NOT ASSIGNED
Occupied Air Change Rate
Unoccupied Air Change Rate
NOT ASSIGNED
N
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
Loads
N
N
N
Misc Cond U-Factor
Misc Cond Ref Temp at Des Sum
Misc Cond Ref Temp at Des Win
NOT ASSIGNED
Lighting - Total Watts
N
(deg F)
N (deg F)
N
Lighting - Watts/ft2
Lighting - Percent Heat to Space
NOT ASSIGNED
Number of People
Square Feet per person
NOT ASSIGNED
Misc Elect - Total Watts
Misc Elect - Watts/ft2
NOT ASSIGNED
Misc Sensible - Total BTUH
Misc Sensible - BTUH/ft2
NOT ASSIGNED
Ext Shading - Overhang depth
Ext Shading - Recess depth
NOT ASSIGNED
NOT
NOT
NOT
NOT
ASSIGNED
ASSIGNED
ASSIGNED
ASSIGNED
C..3
See Notes
See Notes
N
(to 100)
N
N
N
N
9
N
N
10
11
N See Notes
N See Notes
85
Systems
TOA Heating Off
Systems
Systems
Systems
Systems
Systems
Maximum Heating Temp
Discriminator Control-HTG (DDMZ)
TOA at Maximum Hot Deck Tern (DDMZ)
Maximum Hot Deck Temp (DDMZ)
TOA at Minimum Hot Deck Temp (DDMZ)
Systems
Minimum Hot Deck Temp (DDMZ)
NOT ASSIGNED
TOA Cooling On
Minimum Supply Temp CLG
Discriminator Control - Cooling
Systems
Systems
Systems
Systems
Systems
Systems
101
102
103
104
105
Systems
Systems
Systems
Systems
12
Max Cooling Supply Temp (Disc)
NOT ASSIGNED
TOA Preheat Off
Design Preheat Discharge Temp
NOT ASSIGNED
TOA Humidification Off (OCC)
Winter Relative Humidity (%)
NOT ASSIGNED
TOA Baseboard Off
Baseboard Control Method
106
107
108
109
110
Systems
Systems
Systems
Systems
Percent Load Satisfied - Des Win
Percent Load Satisfied - Min Load
NOT ASSIGNED
Total Supply Fan KW
Supply Fan KW/lOOO CFM
111
112
113
114
115
Systems
Systems
Systems
Systems
Systems
Supply Fan Heat
Total Return Fan KW
Return Fan KW/lOOO CFM
Return Fan Heat
Minimum Percent Flow (VAV)
116
117
118
119
Systems
Systems
Systems
120
Systems
Fan Control Method (VAV)
Fan Operating Method (OCC)
Fan Operating Method (UNOCC)
NOT ASSIGNED
Outside Air Control Method (OCC)
121
122
123
124
125
Systems
Systems
Systems
Systems
Systems
Min Percent Outside
Dry Bulb Switchover
Outside Air Control
Min Percent Outside
Dry Bulb Switchover
15
16
16
Air (OCC)
Temp (OCC)
Method (UNOCC)
Air (UNOCC)
Temp (UNOCC)
126
127
128
21
C.4
N
129
130
Systems
Systems
Furnace % Load Satisfied (auto)
Furnace Efficiency (%)
(to 100)
(to 100)
131
132
133
134
135
Systems
Systems
Systems
Furnace Off Loss - % at Des Win
Furnace Off Loss - % at Min Load
Furnace Pilot Consumption (therms)
NOT ASSIGNED
NOT ASSIGNED
(to 100)
(to 100)
annual #
136
137
138
139
140
Systems
Systems
Systems
Systems
Systems
HP/WAC
HP/WAC
HP/WAC
WSHP WSHP -
141
142
143
144
145
Systems
Systems
WSHP - TOA at Max Flu id Temp
WSHP - Max Fluid Temp
NOT ASSIGNED
NOT ASSIGNED
HP - % Heating Load Satisfied
146
147
148
149
150
Systems
Systems
Systems
Systems
Systems
- % Total Load Satisfied
- % Sensible Load Satisfied
- COP Cooling
TOA at Min Flu i d Temp
Min Fluid Temp
HP - TOA Heat Pump HTG Off (AAHP)
HP - % Load Satisfied - Backup HTG
HP - COP (Heating)
NOT ASSIGNED
Percent Design Air Flow (Central)
151
152
153
154
155
Systems
156
157
158
159
160
Systems
Systems
S W ;
Plant
DX - Min Hot Gas Bypass Ratio
DX - Condenser Fan KW
DX - TOA Condenser Fan Off
DHW Capacity
DHW Occupied Cycle Average Usage
161
162
163
164
165
Plant
Plant
Plant
Plant
Plant
DHW Unoccupied Cycle Average Usage
DHW Efficiency (percent)
DHW Occupied Cycle Losses
DHW Unoccupied Cycle Losses
Chiller Cooling Capacity (tons)
166
167
168
169
170
Plant
Plant
Plant
Plant
Plant
Chiller
Chiller
Chiller
Chiller
Chiller
171
172
173
Plant
Chiller Design Heat Ret Temp (DB)
NOT ASSIGNED
NOT ASSIGNED
Systems
Systems
Systems
Percent Design Zonal Fan KW (Un it)
NOT ASSIGNED
DX - % Total CLG Load Satisfied
DX - COP
DX - Minimum Unloading Ratio
N (deg F)
N (deg F)
22
N
(to 100)
22
N
N
N
(deg F)
(to 100)
22
N
(to 100)
22
N
(to 100)
22
N
(to 100)
N
(to 100)
(to 100)
(Gal/Hr)
N
N
N
24
N4
25
% Max Load Satisfied
COP
Unloading Ratio
Min Part Load Ratio
Unloading Ratio (Heating-DB)
N
C.5
N
N
N
N
174
175
Plant
NOT ASSIGNED
Cooling Tower - % Load Satisfied
25
N (to 100)
176
177
178
179
180
Plant
Plant
Plant
Cooling Tower - Number Cells
Cooling Tower - # Fan Speeds
NOT ASSIGNED
NOT ASSIGNED
Boiler - Heat Capacity (KBTUH)
181
182
183
184
185
Plant
Plant
Plant
Plant
Plant
Boiler
Boiler
Boiler
Boiler
Boiler
186
187
188
189
190
Plant
Boiler NOT
NOT
NOT
NOT
Min Unloading Ratio
ASSIGNED
ASSIGNED
ASSIGNED
ASSIGNED
N (to 100)
191
192
193
194
195
Loads
Loads
Loads
Loads
Building
Building
Building
Daylight
NOT
Latitude
Longitude
Time Zone
Savings Time
ASSIGNED
N (deg)
N (deg)
196
197
198
199
200
Loads
Systems
Plant
LCC
-
% Heat Load Satisfied
Efficiency
Combustion Air Temp
Stack Temp
Air-Fuel Ratio
N2
N2
24
N
25
NOT ASSIGNED
Loads Input Filename
Systems Input Filename
Plant Input Filename
LCC Input Filename
C (Y or N)
C
C
C
C
(Use
(Use
(Use
(Use
F8)
F8)
F8)
F8)
Notes:
Entry Type - 'N' represents a numeric input
'N2' represents a numeric input using the 'new value' method for
changing
'C' represents a character input
There are no error checks for valid input values.
1 Orientation Adjustment - Enter a number from 1 to 7 that corresponds to
the amount of clockwise rotation in increments of 45 degrees. For example,
if you enter "2" (indicating a 90 degree rotation), all south orientations
entered in the base input file will become west orientations for the
calculations. If no rotation is desired, enter either 0 or 8.^T
2 Weather Data Type - Enter one of the following:
1- ASHRAE Bin Weather (filename extension - '.awd')
2 - Battelle Bin Weather (filename extension - '.bwd')
3 - DOD Bin Weather (filename extension - '.dwd')
C.6
3 Bin and Solar Weather Filenames - Enter the eight character weather file
name. These data files must also be stored on your data disk. See also
the notes on (2) above.
4 Starting Hour for Occupancy - Enter integer value from 1 to 24
5 Occupied Hours/Day - Enter one of the following - 8, 10, 12, 14, or 16.
Any other entry is invalid.
6 Daylighting - Note that all THREE daylighting functions will be changed by
this entry.
The sensor location should be one of the following:
1 - Max location (closest to window)
2 - Mid location
3 - Min location (farthest from window)
The daylighting control type should be entered as either 'D' for dimming
or 'S' for stepped control. Note that capital letters should be used.
7 Diversity Factors - ALL zones diversity factors will be changed. This
entry should be in percent (e.g. 70, not .7)
8 Infiltration Air Change Rate - Since the parametric processor changes all
zones to this value, you may want to select the first method (multiply base
value by percent) for changing this variable. By using this method, the
interior zones (assuming no infiltration) would not be changed.
9 Miscellaneous Loads - the BTUH value is positive for heat gains and
negative for heat losses.
10 Overhang depth - this entry is in inches. See notes on (11) below. ALL
three exterior shading models will be changed.
11 Recess depth - this entry is in inches.
This will change three base
case entries simultaneously - the left, right, AND overhang depth.
12 Discriminator Control - The character entry should either be 'Y' or
'N' . Capital letters must be used.
13 Minimum Supply Temp - if you have selected 'autosizing' for the system air
flow, changing this value may change the system sizing.
14 Maximum Cooling Supply Temp - used only if discriminator control is used
in the cooling mode
15 Baseboard Control Method - enter one of the following
1 - Thermostatic Control
2 - Baseboard heating reset by outside air temperature
16 Fan KW - this entry has precedence over the 'KW/1000 CFM' entry
17 Fan Control Method (VAV) - use one of the following:
1 - Variable Speed
2 - Discharge Dampers
C.7
3 - Inlet Vanes
Any other entry is invalid.
18 Fan Operating Method (Occupied Cycle only) - this entry only applies to
systems that are 'zonal' (systems that normally cycle day and night). This
entry does not affect the central systems such as CVRH, DDMZ, VAV, HV,
SZRHi Use one of the following:
1 - On Continuously
2 - Cycles with Load
19 Fan Operating Method (Unoccupied Cycle only) - this entry only applies to
all systems. Use the 1 or 2 code described in note (18) above.
20 Outside Air Control Method - use one of the following codes:
1 - No Outside Air
2- Fixed Percent Outside Air
3 - Dry Bulb Economizer
4 - Enthalpy Economizer
21 Entered Capacity - this entry has precedence over the autosizing option.
22 Autosizing - only used if autosizing is selected
23 TOA Heat Pump Heating Off - for Air/Air Heat Pump Only. When the outside
air temperature is below this value, backup heating is used.
24 Plant Capacity - enter value per unit (e.g. if two chillers or boilers are
specified in the base file, entry the capacity of each chiller or boiler
- not the combined capacity)
25 Plant Capacity (autosizing) - enter percent of,maximum load per unit
(e.g.) if two chillers or boilers are specified in the base file, entrY the
percent capacity of each chiller or boiler - not the combined capacity )
C.8
Parametric Output Variables
OUTPUT
VARIABLE
DESCRIPTION
UNITS
VARIABLE
TYPE
NUMBER
VAR!:BLE
===================================================================
Heating Energy
Electric Resistance
KWH
Heating Energy
Heat Pump
KWH
Heating Energy
Gas Boiler
therms
Heating Energy
Oil Boiler
gal
Heating Energy
Electric Boiler
KWH
Heating
Heating
Heating
Heating
Cooling
Energy
Energy
Energy
Energy
Energy
District Heating
Gas Furnace
Oil Furnace
Electric Furnace
Direct Expansion
MBTU
therms
gal
KWH
KWH
Cooling
Cooling
Cooling
Cooling
Cooling
Energy
Energy
Energy
Energy
Energy
Centrifugal Chiller
Absorption Chiller
District Cooling
Double Bundle Chiller
Reciprocating Chiller
KWH
KWH
MBTU
KWH
KWH
Cooling Energy
Cooling Energy
DHW Energy
DHW Energy
DHW Energy
Window A/C Units
Heat Pump
Domestic HW Heater
Domestic HW Heater
Domestic HW Heater
KWH
KWH
therms
gal
KWH
DHW Energy
Building Misc.
Building Misc.
Building Misc.
System Misc.
Domestic HW Heater
Lights
Equipment
Miscellaneous
Fans
MBTU
KWH
KWH
KWH
KWH
Not Assigned
Cooling Tower
Plant Misc.
Plant Misc.
Pumping
Not Assigned
Monthly Gas Consumption
Monthly Oil Consumption
Monthly Electric Consumption
Monthly District Heating Consumption
Monthly District Cooling Consumption
(See Note Below)
Peak Loads Report
Not
Not
Not
Not
Assigned
Assigned
Assigned
Assigned
Total Gas Consumption
C.9
KWH
KWH
therms
gal
KWH
MBTU
MBTU
therms
41
42
43
44
45
46
47
48
50
51
52
53
54
56
57
58
59
Not
Assigned
Not
Not
Not
Not
Assigned
Assigned
Assigned
Assigned
Not
Not
Not
Not
Assigned
Assigned
Assigned
Assigned
Not
Not
Not
Not
Assigned
Assigned
Assigned
Assigned
Total
Total
Total
Total
Oil Consumption
Electrical Cons
District Heating
District Cooling
gal
KWH
MBTU
MBTU
Total Energy Cost
Total Site Energy
MBTU
Total Source Energy
MBTU
NOTE - Output variable numbers 30 to 35 are used to store monthly
consumption and zone peak loads analysis. An separate output file for
these results is generated at the end of the calculations. This file
can be imported into LOTUS with the template.
C.10