ANSI/ASHRAE Standard 209-2018
Energy Simulation Aided
Design for Buildings
Except Low-Rise
Residential Buildings
Approved by ASHRAE on March 30, 2018, and by the American National Standards Institute on April 2, 2018.
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© 2018 ASHRAE
ISSN 1041-2336
ASHRAE Standard Project Committee 209
Cognizant TC: 4.7, Energy Calculations
SPLS Liaison: Julie Ferguso
Jason J. Glazer*, Chair
Christopher B. Baker*
Mangesh S. Basarkar
Mahabir S. Bhandari
William J. Bishop*
John Bixler
Yu Chen*
Michael M. Collarin
Drury B. Crawley*
Margaret P. Curtz*
Lee DeBaillie
Clark R. Denson*
Gregory Dobbs*
Mathew Edwards
Delia Estrada
Ross C. Farris*
Paul A Fiejdasz*
Ellen M. Franconi*
Lixing Gu*
Jeff S. Haberl
Kamel Haddad
Daniel A. Katzenberger*
Erik P. Kolderup
Luka Matutinovic*
Dembia Ndiaye*
Ronald O. Nelson*
Jerry W. Phelan*
David Reddy*
Andrew Reilman*
Marcus B. Sheffer*
Kim E. Shinn*
Som S. Shrestha*
Aaron R. Smith*
Seth P. Spangler
Liangcai Tan*
Scott P. West*
Yun K. Yi
* Denotes members of voting status when the document was approved for publication
ASHRAE STANDARDS COMMITTEE 2017–2018
Steven J. Emmerich, Chair
Donald M. Brundage, Vice-Chair
Niels Bidstrup
Michael D. Corbat
Drury B. Crawley
Julie M. Ferguson
Michael W. Gallagher
Walter T. Grondzik
Vinod P. Gupta
Susanna S. Hanson
Roger L. Hedrick
Rick M. Heiden
Jonathan Humble
Srinivas Katipamula
Kwang Woo Kim
Larry Kouma
Arsen K. Melikov
R. Lee Millies, Jr.
Karl L. Peterman
Erick A. Phelps
David Robin
Peter Simmonds
Dennis A. Stanke
Wayne H. Stoppelmoor, Jr.
Richard T. Swierczyna
Jack H. Zarour
Lawrence C. Markel, BOD ExO
M. Ginger Scoggins, CO
Steven C. Ferguson, Senior Manager of Standards
SPECIAL NOTE
This American National Standard (ANS) is a national voluntary consensus Standard developed under the auspices of ASHRAE. Consensus is defined by the
American National Standards Institute (ANSI), of which ASHRAE is a member and which has approved this Standard as an ANS, as “substantial agreement
reached by directly and materially affected interest categories. This signifies the concurrence of more than a simple majority, but not necessarily unanimity.
Consensus requires that all views and objections be considered, and that an effort be made toward their resolution.” Compliance with this Standard is
voluntary until and unless a legal jurisdiction makes compliance mandatory through legislation.
ASHRAE obtains consensus through participation of its national and international members, associated societies, and public review.
ASHRAE Standards are prepared by a Project Committee appointed specifically for the purpose of writing the Standard. The Project Committee
Chair and Vice-Chair must be members of ASHRAE; while other committee members may or may not be ASHRAE members, all must be technically
qualified in the subject area of the Standard. Every effort is made to balance the concerned interests on all Project Committees.
The Senior Manager of Standards of ASHRAE should be contacted for
a. interpretation of the contents of this Standard,
b. participation in the next review of the Standard,
c. offering constructive criticism for improving the Standard, or
d. permission to reprint portions of the Standard.
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product has been approved by ASHRAE.
CONTENTS
ANSI/ASHRAE Standard 209-2018
Energy Simulation Aided Design for Buildings Except Low-Rise Residential Buildings
SECTION
PAGE
Foreword .....................................................................................................................................................................2
1 Purpose.............................................................................................................................................................2
2 Scope ................................................................................................................................................................2
3 Definitions, Abbreviations, and Acronyms.........................................................................................................2
4 Utilization...........................................................................................................................................................4
5 General Requirements ......................................................................................................................................4
6 Design Modeling Cycles....................................................................................................................................7
7 Construction and Operations Modeling.............................................................................................................8
8 Postoccupancy Modeling ..................................................................................................................................9
9 Normative References ....................................................................................................................................10
Informative Appendix A: Climate Information ........................................................................................................11
Informative Appendix B: Benchmark Information ..................................................................................................12
Informative Appendix C: Simple Box Modeling .....................................................................................................13
Informative Appendix D: Owner’s Project Requirements ......................................................................................14
Informative Appendix E: Quality Assurance and Quality Control Checklists.........................................................16
Informative Appendix F: Informative References ..................................................................................................20
NOTE
Approved addenda, errata, or interpretations for this standard can be downloaded free of charge from the ASHRAE
website at www.ashrae.org/technology.
© 2018 ASHRAE
1791 Tullie Circle NE · Atlanta, GA 30329 · www.ashrae.org · All rights reserved.
ASHRAE is a registered trademark of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.
ANSI is a registered trademark of the American National Standards Institute.
(This foreword is not part of this standard. It is merely
informative and does not contain requirements necessary
for conformance to the standard. It has not been processed according to the ANSI requirements for a standard
and may contain material that has not been subject to
public review or a consensus process. Unresolved objectors on informative material are not offered the right to
appeal at ASHRAE or ANSI.)
FOREWORD
ASHRAE Standard 209 describes a methodology to apply
building energy modeling to the design process. The Standard
Project Committee recognizes the important role building
energy modeling plays in informing the design and operation
of low-energy buildings. The standard was created to define
reliable and consistent procedures that advance the use of
timely energy modeling to quantify the impact of design decisions at the point in time at which they are being made. The
committee believes such an approach will improve modeling
effectiveness, realize greater savings, and support achieving
increasingly aggressive energy savings targets.
The standard defines general modeling requirements coupled with eleven modeling cycles, each with specific modeling
goals that align with distinct phases of the design, construction,
or operation process. Each modeling cycle is an extension of
the general modeling requirements, which represents a bestpractices approach for using modeling to inform design. Seven
of the modeling cycles coincide with the building design phase,
three modeling cycles are applied during building construction,
and one occurs postoccupancy. The postoccupancy analysis is
included to help both the owner and modeler understand how
modeled results compare to actual energy performance to
inform operation and assumptions used in future modeling
projects.
The minimum requirements of the standard can be met by
completing a load-reducing modeling cycle early in the
design process, as well as one additional design-phase modeling cycle. The full set of modeling cycles were developed to
provide holistic modeling guidance and are included for completeness. They can be selectively adopted by organizations
that desire a more robust treatment for realizing their specific
project objectives. While the standard can be applied with
any design process, it is best utilized when included as part of
an integrative design process.
It is expected the standard will be adopted by organizations that certify high-performance buildings, as well as by
utilities and agencies that provide incentives for using modeling to inform design. It can be referenced as part of a project
scope of work by building owners and architects seeking an
effective, uniform way to use energy modeling to achieve performance objectives.
1. PURPOSE
Define minimum requirements for providing energy design
assistance using building energy simulation and analysis.
during the design process. This standard does not apply to
single-family houses, multifamily structures of three stories
or fewer above grade, manufactured houses (mobile homes),
or modular homes.
3. DEFINITIONS, ABBREVIATIONS, AND ACRONYMS
3.1 General
Certain terms, abbreviations, and acronyms are defined in this
section for the purposes of this standard. These definitions are
applicable to all sections of this standard.
3.2 Definitions
actual meteorological year (AMY): a data set comprising one
year of historical, hourly measured or derived weather observations for a specific location.
authority having jurisdiction (AHJ): the agency or agent
responsible for enforcing this standard.
balance-point temperature: the outdoor temperature at which
a building’s heat loss to the environment is equal to internal
heat gains from people, lights, and equipment.
baseline: the building design or level of energy performance
used as the basis of comparison against other project alternatives, usually based on a hypothetical design defined by building standards or based on the currently proposed building
design at the time of modeling cycle analysis.
building energy simulation: building energy estimation using
a computer simulation program.
building performance rating system: a program to assess
energy and/or environmental performance of a building
design. (Informative Note: e.g., the Leadership in Energy and
Environmental Design [LEED] program developed by the
U.S. Green Building Council and the Green Globes program
developed by the Green Building Initiative.)
change order: a request to modify the original scope of work
after construction has begun. The need for a change order can
include product substitutions, design changes, and differing
site conditions. A request for a change order may be originated by the owner, a member of the design team, the contractor, or a subcontractor and typically is initiated using either a
change order proposal request, a change order proposal, or a
change directive. If approved, change orders permanently
modify the scope of work and contract.
charrette: a meeting of project stakeholders to discuss design
goals and design strategies.
comparative analysis: a modeling exercise comparing the
performance of two or more design alternatives in which the
important result is the relative performance of alternatives.
compliance analysis: a modeling exercise to demonstrate
design compliance with energy standards or other program
requirements.
2. SCOPE
construction document phase: the final portion of the design
process in which detailed plans and specifications are completed.
This standard applies to new buildings or major renovations
of, or additions to, existing buildings using energy simulation
design constraint: a condition that must be satisfied as a part
of an optimization process in order for a design to be feasible.
2
ANSI/ASHRAE Standard 209-2018
design variable: a building parameter or specification that is
controllable from the point of view of the designer.
energy design assistance: the process of using energy modeling to provide information to the owner and building design
team regarding the energy performance of project alternatives
with the intent to achieve an energy efficient design.
energy efficiency measure (EEM): an action taken in the
operation of, or a change to, equipment in a building that
reduces the energy use of the building while maintaining or
enhancing the building’s safety, comfort, and functionality.
energy end use: a component of building energy consumption
due to a specific application, including but not limited to lights,
internal equipment loads, service water heating equipment, space
heating equipment, space cooling and heat rejection equipment,
fans, and other HVAC system equipment (such as pumps).
energy model: a computer representation that provides information on the systems (e.g., HVAC, lighting, occupancy, plug
loads, building envelope) that affect energy consumption in a
building. The representation of the building serves, along
with weather data, as the input data for a computer simulation
program. When run, the program will simulate the energy use
and demand in the described building for a time interval.
Depending on the kind of program and how it is set up to run,
various kinds of output may be produced.
local weather station: the weather station geographically
closest to the building site or having similar climate characteristics as the building site.
modeling cycle: an energy modeling activity with a specific
purpose, applicability, and analysis approach.
optimization: an energy modeling aided process in which one
or more design variables are selected and analyzed through a
given test range or set of design constraints in order to maximize or minimize an optimization objective relating to one or
more of the project performance goals.
optimization objective: a numerical value that is to be maximized or minimized as a part of an optimization process.
owner’s project requirements (OPR): a written document that
details the requirements of a project and the expectations for
how it will be designed, constructed, and operated. This
includes project goals, measurable performance criteria, cost
considerations, benchmarks, success criteria, and supporting
information. (Informative Note: The terms project intent or
design intent are used interchangeably with OPR by some
owners. See Informative Appendix D.)
process energy: energy consumed in support of a manufacturing, industrial, or commercial process other than conditioning
spaces and maintaining comfort and amenities for the occupants of a building.
energy modeler: an individual with primary responsibility for
performance of the activities defined in this standard.
process load: the load on a building resulting from the consumption or release of process energy.
energy modeling: the process of developing an energy model
and running a building energy simulation.
project alternative: an energy efficiency measure, proposed
value engineering measure, change order proposal, or other
change to the building design or operation that impacts building energy performance and is being considered for evaluation.
energy source: electricity, natural gas, fuel oil, propane, purchased heating, purchased cooling, and other building energy
utility inputs.
green building concepts: measures that minimize the impact
of buildings on the natural environment or that improve the
indoor environment for occupants.
gross floor area: the sum of the floor areas of all the spaces
within the building with no deductions for floor penetrations
other than atria. Gross floor area is measured from the exterior faces of exterior walls or from the centerline of walls separating buildings, but it excludes covered walkways, open
roofed-over areas, porches and similar spaces, pipe trenches,
exterior terraces or steps, roof overhangs, parking garages,
surface parking, and similar features.
schematic design: the early design phase in which fundamental elements of design, such as building form and HVAC system type, are typically determined.
simple box model: a simplified building representation used
during the early design stage. (Informative Note: See Informative Appendix C for additional information.)
simulation program: a computer program that is capable of
simulating the energy performance of building systems.
site energy: energy consumed by the building as measured by
the local utility and/or nonutility meters.
HVAC system: the equipment, distribution systems, and terminals that provide, either collectively or individually, the
processes of heating, ventilating, or air conditioning to a
building or portion of a building.
value engineering (VE): a process through which one or
more project alternatives are identified that affect the cost
and/or function of a building, system, or component. The typical goal is to maximize value by providing the necessary
function at minimum cost. Also known as value management,
value methodology, or value analysis.
insolation: incident or incoming solar radiation to a specific
location.
whole-building simulation software: see simulation program.
life-cycle cost analysis (LCCA): an economic method for
evaluating a project or project alternatives in which the net
present value of costs arising from owning, operating, maintaining, and ultimately disposing of a project are computed
for each alternative and then compared over a designated
study period.
3.3 Abbreviations and Acronyms
ANSI/ASHRAE Standard 209-2018
AFUE
annual fuel utilization efficiency
AHJ
authority having jurisdiction
AMY
actual meteorological year
BEMP
building energy modeling professional
3
BESA
building energy simulation analyst
VLT
visible light transmittance
bhp
brake horsepower
W
watt
Btu
British thermal unit
W/ft²
watt per square foot
Btu/h
British thermal unit per hour
C
Celsius
CDD
cooling degree days
cfm
cubic feet per minute
CHW
chilled water
CO
change orders
COP
coefficient of performance
CVRMSE
coefficient of variation of the root-mean-square
error
ECI
Energy Cost Index
EEM
energy efficiency measure
EER
energy efficiency ratio
EF
energy factor
EUI
energy use intensity
F
Fahrenheit
ft
foot
gpm
gallons per minute
gpf
gallons per flush
h
hour
HDD
heating degree days
hp
horsepower
HSPF
heating seasonal performance factor
HVAC
heating, ventilating, and air conditioning
IEER
integrated energy efficiency ratio
I-P
inch-pound
IPLV
integrated part-load value
IMT
inverse modeling toolkit
in.
inch
LCCA
life-cycle cost analysis
LPD
lighting power density
NMBE
normalized mean bias error
LSG
light to solar gain
OPR
owner’s project requirements
QA
quality assurance
QC
quality control
SEER
seasonal energy efficiency ratio
SHGC
solar heat gain coefficient
SWH
service water heating
5. GENERAL REQUIREMENTS
TMY
typical meteorological year
UA
overall heat transfer coefficient × area
VE
value engineering
5.1 Simulation Software Requirements. Whole-building
simulation software used to comply with the standard shall
meet the minimum requirements of ASHRAE/IES Standard
90.1 1, Section G2.2.
4
4. UTILIZATION
4.1 Timing of Work. The energy modeler shall perform
energy modeling at each phase of the planning, design, and
construction or operation of the building as specified in the
owner’s project requirements (OPR) or in the owner/energy
modeler agreement and using information obtained from relevant project stakeholders, which may include the owner,
design team, constructors, and operators. The modeler shall
provide the results of the required simulations with opinions
and recommendations, as required and appropriate for the
modeling cycle being evaluated, in order to inform decision
making by stakeholders.
4.2 Compliance
4.2.1 The building design process shall meet the requirements of
a. Section 5,
b. Section 6.3, “Modeling Cycle #3—Load Reduction Modeling,” and
c. at least one of the following sections:
1. Section 6.1, “Modeling Cycle #1—Simple Box Modeling”
2. Section 6.2, “Modeling Cycle #2—Conceptual Design
Modeling”
3. Section 6.4, “Modeling Cycle #4—HVAC System
Selection Modeling”
4. Section 6.5, “Modeling Cycle #5—Design Refinement”
5. Section 6.6, “Modeling Cycle #6—Design Integration
and Optimization”
6. Section 6.7, “Modeling Cycle #7—Energy Simulation
Aided Value Engineering”
4.2.2 The adopting authority shall have the option of
requiring additional levels of compliance:
a. Additional modeling cycles.
b. As-designed compliance. Meet the requirements listed in
Section 4.2.1 and, additionally, the requirements in Section
7.1, “Modeling Cycle #8—As-Designed Energy Performance.”
c. As-built compliance. Meet the requirements listed in Section 4.2.1 and, additionally, the requirements in Section
7.3, “Modeling Cycle #10—As-Built Energy Performance.”
d. As-operated compliance. Meet the requirements listed in
Section 4.2.1 and, additionally, the requirements in Section 8.1, “Modeling Cycle #11—Postoccupancy Energy
Performance Comparison.”
ANSI/ASHRAE Standard 209-2018
5.2 Modeler Credentials. The energy modeler or the individual supervising the work of the energy modeler shall be
a. a certified Building Energy Modeling Professional (BEMP),
or
b. a certified Building Energy Simulation Analyst (BESA)
who also fulfills the BEMP eligibility requirements, or
c. an equivalent individual meeting qualifications established by the authority having jurisdiction (AHJ).
Informative Note: ASHRAE and AEE are two organizations that can certify a modeler for BEMP or BESA, respectively.
5.3 Climate and Site Analysis
5.3.1 Prior to Modeling Cycle #2, if Modeling Cycle #2 is
used for compliance, or prior to Modeling Cycle #3, review
local climate information. Record the minimum following
information for the project site:
a. Dry-bulb temperatures (monthly minimum, maximum,
and mean)
b. Relative humidity or wet-bulb temperature (monthly minimum, maximum, and mean)
c. Wind speed and direction (monthly average and maximum)
d. Insolation (average daily per month)
e. Cloud cover (monthly minimum, maximum, and mean)
f. Ground temperature (monthly average)
g. Precipitation (monthly total)
h. Heating and cooling degree days, including base temperature for each (monthly total)
Informative Note: See informative Appendix A for
resources on climate information.
5.3.2 Assess site characteristics to determine their impact
on building energy performance.
5.3.3 In collaboration with relevant project stakeholders,
document a list of building design strategies that are adapted
to the local climate and site conditions.
5.4 Benchmarking. Determine the energy use of buildings
with the same principal building activities in the same climate
and determine their energy costs using applicable local utility
rates. These data shall be used in the energy charrette described
in Section 5.5 to inform the development of the project energy
goals.
Informative Note: See Informative Appendix B for additional information on benchmarking.
5.5 Energy Charrette
5.5.1 Prior to Modeling Cycle #2, if Modeling Cycle #2 is
used for compliance, or prior to Modeling Cycle #3, the project team shall conduct at least one charrette.
5.5.2 The representatives that participate in the charrette
shall, at a minimum, include the following:
a. Owner or owner representatives
b. Architect
c. Engineer
ANSI/ASHRAE Standard 209-2018
d. Building performance rating system consultant (if applicable)
e. Energy modeler or the individual supervising the work of
the energy modeler
f. Other design team members required to reconcile technical requirements
g. Contractor (if applicable)
5.5.3 Determine and document the purposes for including
energy modeling in the proposed project. Energy modeling
purposes to be discussed shall include both comparative analysis and compliance analysis.
5.5.4 Define the baseline or baselines to be used for comparative analysis.
5.5.5 Establish project performance metrics to be used as
the basis for the energy goals.
5.5.6 Use benchmarking data generated in Section 5.4 to
inform the discussion and determination of the energy performance goals. The resulting energy performance goals shall be
incorporated into the draft owner’s project requirements
(OPR) detailed in Section 5.6.
5.5.7 Discuss and determine the method for evaluating the
potential energy efficiency measures (EEMs) for the project.
5.5.8 Generate a list of potential EEMs.
5.5.9 The energy modeler shall present the results of any
previously performed modeling analysis deemed relevant to
design decisions associated with the project.
5.5.10 Establish financial criteria for financial analysis and
decision making.
5.5.11 Establish a project schedule for follow-up tasks
related to items discussed during the charrette.
5.5.12 Establish the process, documentation, and review
team for complying with Section 5.7.4 for each modeling
cycle.
5.5.13 Create a written record of items discussed during the
charrette.
5.6 Energy Performance Goals in OPR
5.6.1 Prior to Modeling Cycle #2, if Modeling Cycle #2 is
used for compliance, or prior to Modeling Cycle #3, the
owner, the energy modeler, and other building team members
shall develop and document the energy performance goals in
the OPR.
5.6.2 Document building performance rating systems that
apply to this project.
5.6.3 Document the financial criteria for decision making
and life-cycle cost analysis (LCCA).
5.6.4 Document the overall project energy performance
goal.
5.6.5 Document the performance goals for the individual
building systems and assemblies in the following subsections,
with the intent that these goals be tracked throughout the
design process.
Informative Note: See Informative Appendix D. The
OPR shall address the building systems for achieving the
energy performance goal.
5
5.6.5.1 Building envelope, including roofs, walls, floors,
doors, fenestration, and infiltration rate.
5.6.5.2 HVAC systems, ventilation, and control strategies.
5.6.5.3 Lighting systems and daylighting systems.
5.6.5.4 Service hot-water systems and flow rate restrictors to hot-water fixtures, fittings, and appliances.
5.6.5.5 Equipment related to plug and process energy use.
5.6.5.6 Specific owner and occupant requirements related
to energy performance.
5.6.5.7 Green building concepts (optional).
5.6.6 Energy performance goals in the OPR shall be
updated as required throughout the design process.
5.7 General Modeling Cycle Requirements. This section
lists requirements that are common to all of the modeling
cycles included within the standard. Cycle-specific requirements are included in their respective sections.
5.7.1 Energy Baselines and Goals. Prior to engaging a
specific modeling cycle, review and update the following
project-level items:
a. The baseline or baselines used for comparison during
energy analysis
b. The energy performance goals as reported in Section 5.6.4
5.7.2 Input Data
5.7.2.1 Prior to each modeling cycle, the project team
shall discuss the purpose, input data, and analysis methodology for each modeling cycle.
5.7.2.2 The input data necessary to perform the analysis,
in conjunction with the purpose and goals of each modeling
cycle, shall be gathered by the energy modeler and jointly
supplied by the project team.
5.7.2.3 Where project-specific modeling inputs are provided, they shall be used in place of assumptions or simulation program default inputs.
5.7.2.4 Input data shall be subject to quality assurance
review as described in Section 5.7.4.2.
5.7.2.5 When a modeling cycle requires the comparison
of project alternatives, the project team shall identify the
first-cost implications of each alternative. This shall include
calculation of the incremental costs of individual strategies or
bundles of strategies relative to a baseline cost. Include added
construction costs as well as reductions in construction costs
due to the downsizing or elimination of building systems,
such as in the case of alternatives that reduce heating or cooling loads.
Exception to 5.7.2.5: Quantification of first-cost impacts
are not required for Modeling Cycles #1 and #2, and
only a qualification of first costs is required for these
modeling cycles.
5.7.3 Reporting. At a minimum, provide the following
information, and explicitly display all units of measure.
5.7.3.1 Narrative. For each modeling cycle, provide a
written narrative of the following items:
a. A comparison of the modeling results to the energy performance goal
6
b. A discussion of the impact to the building peak heating
and cooling loads
c. A financial analysis of the overall costs and savings
d. Discussion of areas of uncertainty in the analysis
e. Recommendations for building design strategies and
acceptance, rejection, or modification of alternatives that
were analyzed
f. Recommendations for additional analysis
5.7.3.2 Input Data Reporting. For each modeling cycle,
provide the following information:
a. Project title
b. Project location and weather station name and type
c. A narrative description of the building, including use type,
occupancy, gross floor area, conditioned floor area, number of stories, occupancy pattern or patterns, internal
loads, and schedules
d. Simulation program and version
e. A narrative description of the energy model baseline,
including discussion of why the selected baseline is
appropriate for the current analysis
f. Utility rates
g. A narrative description of any on-site energy generation
h. For each project alternative, provide a narrative description of the alternative, including analysis methodology
utilized, relevant baseline, and proposed parameters and
values
i. A summary table of the major energy modeling inputs
5.7.3.3 Output Data Reporting. For the baseline, and
for each project alternative, report the following annual
results:
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
Total site energy consumption
Total site energy consumption per unit gross floor area
Site energy consumption by energy end use
Total energy cost
Consumption by energy source
Cost by energy source
Peak cooling demand and time of occurrence (date, day of
week, day type, hour)
Peak heating demand and time of occurrence (date, day of
week, day type, hour)
Calendar month peak electric demand and time of occurrence (date, day of week, day type, hour)
Calendar month peak energy consumption by energy
source
Unmet heating and cooling load hours
Construction cost as determined per Section 5.7.2.5
5.7.4 Quality Assurance. Each Section 6 and 7 modeling
cycle shall have two reviews: an input review and an output
review. When Modeling Cycle #11 is performed, it shall have
an output review.
5.7.4.1 Quality Assurance Review Team. The review
team shall include the following, at a minimum:
a. Energy modeler
b. Owner (or owner representative)
c. Architect
ANSI/ASHRAE Standard 209-2018
d. Mechanical designer
e. Electrical or lighting designer
f. Facility operator (for Modeling Cycle #11 reviews)
5.7.4.2 Modeling Cycle Input Reviews. The review team
shall review the input data as listed in Section 5.7.3.2 and complete the quality assurance process and review documentation
established in Section 5.5.12. The review team shall approve
model inputs or suggest changes to model inputs.
5.7.4.3 Modeling Cycle Output Reviews. The review
team shall
a.
b.
c.
d.
review documentation for Sections 5.7.3;
compare results to benchmark established in Section 5.4;
compare results to energy performance goals in Section 5.6;
evaluate results, including energy end uses, relative to
inputs; and
e. complete quality assurance process and review documentation established in Section 5.5.12.
5.7.5 Modeler Quality Control. The energy modeler shall
follow a quality control process related to the energy model.
At a minimum, this process shall include quality control procedures provided by the energy modeling software developer,
or a generic quality control checklist.
Informative Note: See Informative Appendix E for an
example quality control checklist.
6. DESIGN MODELING CYCLES
6.1 Modeling Cycle # 1—Simple Box Modeling
6.1.1 Purpose. Identify the distribution of energy by end
use. Evaluate energy end uses and demand characteristics that
affect building conceptual design.
6.1.2 Applicability. This modeling cycle applies before the
building’s geometry and site orientation have been set in the
design process. This must be completed before or during the
energy charrette described in Section 5.5.
6.1.3 Analysis. Create energy models to calculate annual
building energy by end use and peak heating and cooling
loads with identical HVAC systems. Perform a sensitivity
analysis by varying the following building characteristics:
a. Building geometry
b. Window-to-wall ratio, by orientation, and shading options
(if applicable)
c. Orientation
d. Thermal performance of the envelope and structure
Informative Note: See Informative Appendix C for guidance.
6.2 Modeling Cycle #2—Conceptual Design Modeling
6.2.1 Purpose. Evaluate energy improvements that are tied
to the form and architecture of the building.
6.2.2 Applicability. This modeling cycle applies to projects
where the form and architecture of the building are still subject
to design changes before schematic design begins. This modeling cycle applies to buildings with internal equipment/process
loads less than 75% of overall energy breakdown.
ANSI/ASHRAE Standard 209-2018
6.2.3 Analysis. Create energy models based on architectural conceptual designs to calculate annual building energy
by end use and peak heating and cooling loads with identical
HVAC systems.
6.2.3.1 Perform comparative analyses of the conceptual
designs.
6.2.3.2 Provide recommendations to improve the energy
performance of each conceptual design.
6.3 Modeling Cycle #3—Load Reduction Modeling
6.3.1 Purpose. Identify the distribution of energy by end
use. Evaluate strategies that will reduce annual energy use
and heating and cooling peak loads.
6.3.2 Applicability. Required for all projects, this modeling cycle shall be completed prior to the final selection of
HVAC system type and prior to the end of schematic design.
6.3.3 Analysis
6.3.3.1 Create an energy model based on the baseline
design, and calculate the annual energy end uses and heating
and cooling peak loads.
6.3.3.2 Develop a list of at least three peak load reduction strategies selected from one or more of the following
categories:
a. Building envelope (including, but not limited to, insulation
level, window-to-wall ratio, glazing performance, shading,
infiltration, phase change materials, and thermal mass)
b. Lighting and daylighting
c. Internal equipment loads
d. Outdoor air (including, but not limited to, outdoor airflow,
exhaust air, and energy recovery)
e. Passive conditioning and natural ventilation
When internal equipment loads exceed 60% of the building energy end use, at least two of the strategies shall be
selected from the internal equipment loads category.
6.3.3.3 Use energy modeling to evaluate each load reduction strategy compared to the baseline design using identical
HVAC system types.
6.4 Modeling Cycle #4—HVAC System Selection Modeling
6.4.1 Purpose. Estimate the annual energy and demand
impacts of HVAC system options.
6.4.2 Applicability. This modeling cycle shall be applicable prior to HVAC system selection. When this modeling cycle
is used to show compliance with the standard, it shall be
started after Modeling Cycle #3 is complete.
6.4.3 Analysis. Use energy modeling to evaluate a minimum of two alternate HVAC systems.
6.5 Modeling Cycle #5—Design Refinement
6.5.1 Purpose. Use energy modeling to evaluate systems in
the building, confirm current design directions, and support
further development of the building design.
6.5.2 Applicability
6.5.2.1 When this modeling cycle is used to show compliance with the standard, it shall be started after the completion
7
of Modeling Cycle #3 and completed before the end of the
construction document phase.
6.5.2.2 Prior to commencing Modeling Cycle #5, a design
direction shall be defined for the building form and orientation,
the HVAC system type or types, service water heating system
type or types, and a space programming scheme.
6.5.3 Analysis. Use energy modeling to refine and develop
the design of at least one building system, including, but not
limited to the following:
a.
b.
c.
d.
e.
HVAC systems
Lighting systems
Envelope systems
Service water heating systems
Process and plug-load systems
6.6 Modeling Cycle #6—Design Integration and Optimization
6.6.1 Purpose. Integrate building systems through an optimization process to assist in meeting one or more of the project performance goals by exploring the complex interactions
of multiple variables.
6.6.2 Applicability. When this modeling cycle is used to
show compliance with the standard, it shall be completed
before the end of the construction document phase.
6.6.3 Analysis
6.6.3.1 The energy modeler shall identify one or more
optimization objectives for the analysis that relates to the
energy performance goals as identified in Section 5.6.
6.6.3.2 The energy modeler shall identify at least two
design variables of interest for a multivariate optimization
process.
6.6.3.3 The energy modeler shall identify the design constraints or test range for each analyzed design variable.
6.6.3.4 Conduct an optimization analysis using the
defined optimization objective or optimization objectives,
design variable or design variables, and design constraints.
Informative Note: An optimization analysis does not
guarantee that the global minimum or maximum of the optimization objective will be found, only a local minimum or
maximum given the design variables, design constraints, initializing values, and optimization method.
6.6.4 Reporting. In addition to the general reporting
requirements in Section 5.7.3, for each design optimization
measure, report the following:
a.
b.
c.
d.
Optimization objective or optimization objectives
Design variable or design variables analyzed
Design constraints or test range for each design variable
Description of the optimization method
6.7 Modeling Cycle #7—Energy Simulation-Aided Value
Engineering
6.7.1 Purpose. To provide information on the holistic
implications of value engineering measures on project performance goals to ensure more informed design decisions.
6.7.2 Applicability
8
6.7.2.1 This modeling cycle shall be used only if first
costs have been identified for each project alternative to be
evaluated.
6.7.2.2 This modeling cycle shall be used only if the project alternative negatively affects project performance goals.
6.7.3 Analysis
6.7.3.1 Identify project alternatives arising from at least
one value engineering proposal.
6.7.3.2 Identify first-cost and operating-cost consequences to building systems directly and indirectly affected
by the value engineering proposal.
6.7.3.3 Use energy modeling to evaluate each project
alternative.
7. CONSTRUCTION AND OPERATIONS MODELING
7.1 Modeling Cycle #8—As-Designed Energy Performance
7.1.1 Purpose. Develop an energy model to represent the
final design in order to compare as-designed performance to
project goals.
7.1.2 Applicability. This modeling cycle applies only after
construction documents are complete.
7.1.3 Analysis. Develop an energy model with inputs representing the as-designed configuration.
7.2 Modeling Cycle #9—Change Orders
7.2.1 Purpose. Provide feedback on all requests for change
orders (COs) that impact the project’s energy performance
goals.
7.2.2 Applicability. This modeling cycle shall only be used
if the CO negatively affects project performance goals.
7.2.3 Analysis. Prior to initiating construction, identify and
document the process for addressing COs. The process shall
address, at minimum, the topics in the following subsections.
7.2.3.1 Designated parties and responsibilities.
7.2.3.2 Timeframe for the energy modeler to respond to
COs.
7.2.3.3 For each applicable CO, the energy modeler shall
perform one of the following analyses. At least one CO
response must be evaluated with a model update:
a. Qualitative review. Energy modeler provides a written
description of whether the CO will increase or decrease
metrics defined in Section 5.6.
b. Model update. Energy modeler revises the latest proposed
design energy model inputs to represent the CO configuration and reports quantitative estimates of how the CO will
increase or decrease metrics defined in Section 5.6.
7.2.4 Reporting. In addition to the general reporting
requirements in Section 5.7.3, report the following:
a. The process used for addressing COs.
b. For each CO reviewed, identify the level of analysis performed and the decision to accept or reject the CO.
7.3 Modeling Cycle #10—As-Built Energy Performance
ANSI/ASHRAE Standard 209-2018
7.3.1 Purpose. Develop an energy model to represent the
as-built project in order to compare as-built performance to
project goals.
7.3.2 Applicability. This modeling cycle applies only after
construction is complete and as-built drawings and contractor
submittals are complete.
7.3.3 Analysis
7.3.3.1 Develop an energy model with inputs representing
the as-built conditions, including new design information
determined during construction, including, at a minimum, asbuilt drawings and contractor submittals.
7.3.3.2 Occupant- and process-dependent schedules and
loads shall reflect design phase inputs or be adjusted to reflect
new information.
8. POSTOCCUPANCY MODELING
8.1 Modeling Cycle #11—Postoccupancy Energy Performance Comparison
8.1.1 Purpose. Compare the modeled performance of the
last design- or construction-phase energy model to the actual
measured energy use and weather conditions of the building
in operation. This comparison is intended to inform future
energy model assumptions and potentially identify operational energy savings opportunities. The scope of this section
does not include adjusting model inputs to calibrate the
energy model to the measured energy use, though the comparison described is a fundamental first step to any proposed calibration.
8.1.2 Applicability. This modeling cycle shall be performed no sooner than twelve months after initial occupancy.
The comparison year shall include twelve consecutive months
of building operations.
8.1.3 Input Data Sources
8.1.3.1 Typical Weather Year Simulation Results.
Gather the model output data listed in Section 5.7.3.3 for the
proposed design energy model, as simulated with a typical
meteorological year (TMY) weather file.
8.1.3.2 Actual Weather Year Simulation Results.
Acquire an actual meteorological year (AMY) weather file for
the comparison year, and resimulate the same energy model
referenced in Section 8.1.3.1 with the AMY weather file. After
performing the simulation, recompile the model outputs
defined in Section 5.7.3.3.
Exceptions to 8.1.3.2:
1. A representative AMY simulation weather file is
not publicly or commercially available.
2. The energy model input file or modeling software
needed to resimulate the model is not freely available or provided to the energy modeler at the time
of completing this modeling cycle.
8.1.3.3 Weather Data. Extract the hourly outdoor drybulb temperature data from the TMY and AMY weather files.
If exempt from Section 8.1.3.2, obtain hourly outdoor drybulb temperature measurements for the comparison year as
recorded at the building’s local weather station.
ANSI/ASHRAE Standard 209-2018
Exceptions to 8.1.3.3:
1. If hourly weather data for the local weather station
are not available, daily average, maximum, and
minimum data or data from a different weather station may be used.
2. If the energy modeler determines the local weather
station is not a good representation of the building’s local weather conditions, data from a different weather station may be used.
8.1.3.4 Energy Consumption and Demand Data.
Obtain monthly (30 ± 2 days) or shorter time interval site
energy use, and, if applicable, energy cost data for the comparison year for all of the building energy sources. If available, also obtain peak energy demand measurements for each
measurement period.
Exception to 8.1.3.4: The energy measurement interval
may be longer than one month but shall not exceed
65 days.
8.1.4 Analysis. The analysis steps involving measured and
simulated energy data shall be performed using the typical
weather year simulation results. The same analysis shall also
be performed using actual weather year simulation results,
except where exceptions to Section 8.1.3.2 apply.
8.1.4.1 Energy Data Alignment. Align the measured
and simulated energy data sets to correspond to the beginning
and ending days of each calendar month.
8.1.4.2 Energy Data Normalization. Normalize the
energy consumption for each aligned interval by dividing the
value by the number of days in each interval and the building
gross floor area.
8.1.4.3 Typical and Actual Year Weather Metrics. Calculate the following weather parameters for both the typical
and actual comparison years.
8.1.4.3.1 Average, maximum, and minimum dry-bulb
temperature for each month and the year.
8.1.4.3.2 Heating degree days (HDD) and cooling
degree days (CDD), using a common base temperature, for
each month and the year.
8.1.4.4 Modeling Uncertainty. For each energy source
and total energy use, calculate the following metrics to quantify the differences between measured and simulated (TMY,
and if applicable AMY) data sets.
a. Normalized mean bias error (NMBE) as defined in
ASHRAE Guideline 14 2:
n
 i = 1  yi – ŷi NMBE = ---------------------------------n – p  y
b. Coefficient of variation of the root-mean-square error
(CVRMSE) as defined in ASHRAE Guideline 14:
 y i – ŷ i  2

----------------------------
n – p CVRMSE = -------------------------------y
9
where
Table 1 Limits
y
=
measured energy use for each month
NMBE
±5%
ŷ
=
simulated (typical or actual year) energy use for each
month
CVRMSE
15%
y
=
arithmetic mean of the measured monthly data
i
=
interval that the measured and simulated energy data
are aligned to (such as monthly)
n
=
number of intervals (greater than 1) included in the
analysis
p
=
1
8.1.4.5 Regression Analysis. Use the ASHRAE Inverse
Modeling Toolkit (IMT) 3 software or similar methodology to
develop linear regression models that correlate energy use (by
energy source) to outdoor air temperature, heating and cooling degree days, or other relevant independent variables.
Develop regression models for both the measured and simulated (TMY and, if applicable, AMY) data sets, and, from
these models, calculate or infer the following:
a. Balance-point temperature or balance-point temperatures
b. Annual base load energy use
c. Annual energy use associated with heating and/or cooling
seasons
d. Uncertainty metrics defined in Section 8.1.4.4 for the
regression models
Exception to 8.1.4.5: Regression analysis is required only
if Section 8.1.4.5 is specifically adopted by the AHJ.
8.2 Cycle-Specific Reporting
8.2.1 Background Information
a. Definition of the comparison year
b. A brief description of the modeling cycle or phase of
design/construction represented by the latest energy model
c. The TMY weather file location
d. The AMY weather file location or the geographic location
of the building’s local weather station
e. A brief narrative describing differences between the simulated and actual building occupancy during the comparison year
f. The source of measured energy data
g. The floor area used to normalize energy data and costs
8.2.2 Comparison of Actual and Typical Year Weather.
Provide graphical and/or tabular comparisons of the following actual and typical year weather conditions.
a. Monthly and annual average dry-bulb temperature
b. Monthly and annual heating and cooling degree days
10
8.2.3 Comparison of Measured and Simulated Energy
Performance. Provide the following graphical and/or tabular
comparisons of the normalized measured and simulated
(TMY and, if applicable, AMY) data sets.
8.2.3.1 Monthly and total annual energy use for each
energy source individually and for all energy sources combined.
8.2.3.2 Monthly and annual peak energy demand for each
energy source if available.
8.2.3.3 Annual site energy use and cost, by source and
total, divided by the building floor area used in Section
8.1.4.2.
8.2.3.4 An energy signature scatter plot, where the independent and dependent value (x-y coordinates) for each plotted point is defined as follows:
a. Independent variable (x). The average outdoor air temperature for the measured or simulated period.
b. Dependent variable (y). The normalized, total energy use
for the measured or simulated period.
8.2.4 Regression Analysis. If Section 8.1.4.5 is completed,
provide a graphical comparison of each regression model
with its corresponding measured or simulated dataset. Additionally, provide a table summarizing the metrics defined in
Section 8.1.4.5(a) through 8.1.4.5(d).
8.2.5 Narrative. If the uncertainty metrics calculated in
Section 8.1.4.4 exceed the limits listed in Table 1, prepare a
short, qualitative narrative describing the following.
8.2.5.1 How the measured and simulated (TMY and, if
applicable, AMY) data sets differ.
8.2.5.2 A list of possible reasons for the differences.
8.2.5.3 Recommended next steps for resolving the differences or improving building energy performance.
9. NORMATIVE REFERENCES
1. ASHRAE. 2016. ANSI/ASHRAE/IES Standard 90.1,
Energy Standard for Buildings Except Low-Rise Residential Buildings, I-P edition. Atlanta: ASHRAE.
2. ASHRAE. 2014. ASHRAE Guideline 14, Measurement of
Energy, Demand, and Water Savings. Atlanta: ASHRAE.
3. Kissock, J.K., J.S. Haberl, and D.E. Claridge. 2003.
Inverse modeling toolkit: Numerical algorithms (RP1050). ASHRAE Transactions 109(2):425–34.
ANSI/ASHRAE Standard 209-2018
This appendix is not part of this standard. It is merely
informative and does not contain requirements necessary
for conformance to the standard. It has not been processed according to the ANSI requirements for a standard
and may contain material that has not been subject to
public review or a consensus process. Unresolved objectors on informative material are not offered the right to
appeal at ASHRAE or ANSI.
INFORMATIVE APPENDIX A
CLIMATE INFORMATION
This appendix provides information sources for climate data
for building energy modeling. The basic difference between
weather and climate is the period of time used when aggregating the original data. Weather data provide outdoor weather
information, such as dry-bulb air temperature, or wind speed,
for one representative year. Climate data look at the same outdoor weather variables over a multiyear timeframe to define
trends in weather data that can affect a building or its energy
simulation.
Climate data are also being reviewed for the effects
known as “climate change” or “global warming.” Some of the
information sources may provide information on these topics.
Climate change data can be incorporated into an energy modeling analysis to define the risk associated with predicted climate change effects on building energy use and equipment
sizing for peak loads.
Note About Typical Meteorological Year (TMY) and
Actual Meteorological Year (AMY) Weather Data
A typical meteorological year (TMY) weather file contains
typical weather/climate data for a one-year period that has
been statistically derived from the past ten to 30 years of
actual meteorological year (AMY) weather/climate data. The
TMY file is useful for typical baseline weather file input to an
energy modeling analysis. However, the actual weather data
files are not statistically modified. For example, the AMY files
contain actual extremes for a given timeframe. These
extremes may not be present in a TMY file due to the data
analysis methods that define the TMY file. For climate analysis trends, both weather files can be useful, depending on the
judgment of the energy modeler.
1. General information resources
1.1 Crawley, D.B. 1998. Which weather data should you
use for energy simulations of commercial buildings?
ASHRAE Transactions 104:2:498–515.
1.2 Rocky Mountain Institute (RMI)
1.2.1 Elements—software that can convert weather
data file formats, perform statistical analysis,
convert actual weather data into a given file
format
ANSI/ASHRAE Standard 209-2018
1.3 Energy Design Resources, UCLA Energy Design
Tools Group
1.3.1 Climate consultant software
2. Climate data resources
2.1 National Oceanic and Atmospheric Administration
(NOAA), part of the United States (U.S.) Department of Commerce
2.1.1 National Centers for Environmental Information (NCEI)
2.1.2 National Weather Service (NWS) Climate
Services—provides climate information for
U.S. cities:
2.1.2.1 Past weather
2.1.2.2 Climate Prediction Center (CPC): 6
to 14 days, 30 days, and 90 days
predictions
2.2 U.S. Department of Energy (DOE)
2.2.1 EnergyPlus Energy Simulation Software
2.2.1.1 Weather Data Sources—website
contains information on worldwide
weather data sources that may be
applicable for climate data use
2.2.2 National Renewable Energy Laboratory
(NREL)
2.2.2.1 System Advisor Model (SAM)
weather files
2.3 White Box Technologies (WBT) and ASHRAE
2.4 Climate.OneBuilding.org website contains extensive
worldwide weather data sources
2.5 WeatherBank, Inc.
2.6 Weather Source
2.7 American Solar Energy Society (ASES)—primarily
solar insolation data
2.8 Rocky Mountain Institute (RMI)
3. Climate change/global warming models and information
3.1 Intergovernmental Panel on Climate Change (IPCC)
3.2 National Center for Atmospheric Research (NCAR)
community climate model
3.2.1 Community Earth System Model (CESM)
3.2.2 Whole Atmosphere Community Climate
Model (WACCM)
3.3 National Oceanic and Atmospheric Administration
(NOAA) (http://climate.gov)
3.4 Hadley Centre for Climate Change Prediction and
Research at the U.K. Meteorological Office
3.4.1 HadCM3 model
3.5 International Energy Agency (IEA)
3.5.1 Addressing Climate Change Database
3.6 WeatherShift (http://weather-shift.com)
11
This appendix is not part of this standard. It is merely
informative and does not contain requirements necessary
for conformance to the standard. It has not been processed according to the ANSI requirements for a standard
and may contain material that has not been subject to
public review or a consensus process. Unresolved objectors on informative material are not offered the right to
appeal at ASHRAE or ANSI.
INFORMATIVE APPENDIX B
BENCHMARK INFORMATION
This appendix provides information sources for building
energy use data. These data can be used to define a building
energy use benchmark that identifies the energy use for buildings similar to the building undergoing energy modeling analysis. The term similar can refer to buildings that have similar
a.
b.
c.
d.
use/occupants,
location/climate,
building energy use systems (HVAC, electrical, etc.), and
size/orientation.
Determining what similar qualities are most important to
the energy modeling analysis is the job of the energy modeler.
1. General information resources
1.1 Brown, Richard E., T. Walter, L.N. Dunn, C.Y. Custodio, P.A. Mathew, D.M. Cheifetz, E. Alschuler,
and J. Knapstein. 2014. Getting real with energy
data: Using the building performance database to
support data-driven analyses and decision-making.
Proceedings of 2014 ACEEE Summer Study on
Energy Efficiency in Buildings—The Next Generation: Reaching for High Energy Savings. American
Council for an Energy Efficient Economy, Washington, DC. http://aceee.org/files/proceedings/2014/
data/index.htm.
2. National energy use data resources
2.1 United States (U.S.) Department of Energy (DOE)
2.1.1 Building Performance Database (BPD)
2.1.2 Federal Energy Management Program
(FEMP)
12
2.1.2.1 Comprehensive Annual Energy
Data and Sustainability
Performance
2.1.3 Buildings Energy Data Book
2.1.4 U.S. Energy Information Administration
(EIA)
2.1.4.1 Commercial Buildings Energy
Consumption Survey (CBECS)
2.1.4.2 Residential Energy Consumption
Survey (RECS)
2.1.5 High Performance Buildings Database
2.1.6 Commercial Building Energy Asset Scoring
Tool
2.1.7 EnergyPlus Energy Simulation Software—
Commercial Reference Buildings
2.2 United States (U.S.) Environmental Protection
Agency (EPA)
2.2.1 Portfolio Manager—existing buildings
database
2.2.2 Target Finder— new building energy use goal
setter
2.3 Building Owners and Managers Association (BOMA)
2.3.1 BOMA BESt Energy and Environment
Report
2.4 Lawrence Berkeley National Laboratory
2.4.1 LABS 21
2.5 ASHRAE
2.5.1 ASHRAE Standard 100
3. Regional, state, and city energy use data resources
3.1 Northwest Energy Efficiency Alliance (NEEA)
3.1.1 Commercial Building Stock Assessment
(CBSA)
3.2 California Energy Commission
3.2.1 California Commercial End-Use Survey
(CEUS)
3.3 Institute for Market Transformation
3.3.1 Building Energy Performance Policy—
information on state and city building energy
benchmarking and transparency policies
ANSI/ASHRAE Standard 209-2018
This appendix is not part of this standard. It is merely
informative and does not contain requirements necessary
for conformance to the standard. It has not been processed according to the ANSI requirements for a standard
and may contain material that has not been subject to
public review or a consensus process. Unresolved objectors on informative material are not offered the right to
appeal at ASHRAE or ANSI.
INFORMATIVE APPENDIX C
SIMPLE BOX MODELING
1. Create a simple box model using an energy simulation
program. Some programs use preprocessor or expert
(“wizard”) systems to help create these models. The simple box model energy simulation program may use
monthly design day hourly information (288 hour in lieu
of 8760 hour simulation).
2. Initial input parameters
2.1 Where design parameters are known, those should
be used; otherwise, the following should be used to
set input parameters.
2.2 Building type (e.g., assembly, healthcare, hotel/
motel, light manufacturing, office, restaurant, retail,
school, warehouse, laboratory, etc.). The building
type infers information about building program area
allocations and locations (core or perimeter space) as
well as occupancy and internal load information by
program area.
2.3 Building form. If the rough building form has not
been otherwise prescribed, follow the parameters
given in Table 13 of NREL/TP-5500-46861 “U.S.
Department of Energy Commercial Reference Building Models of the National Building Stock.” Aspect
ratio is defined as the overall length in the east-west
direction divided by the overall length in the northsouth direction. If the building type is not one given in
Table 13, and no other information is known, use a
rectangle with an aspect ratio of 1.62, floor-to-floor
height 12.5 ft (3.81 m), flat roof, glazing fraction 30%.
ANSI/ASHRAE Standard 209-2018
2.4 Site location by weather file location. See Section
5.6 for types and sources of weather files.
2.5 Total conditioned square footage. The accuracy of
this parameter should be order of magnitude.
2.6 Number of floors, if known. If not known, use the
number of floors given in Table 13 of NREL/TP-550046861 referenced above. Unless known otherwise,
each of multiple floors shall have the same footprint.
2.7 Fenestration amount. Use Table 13 of NREL/TP5500-46861 or the applicable local energy code or
ASHRAE/IES Standard 90.1, Table G3.1.1-1, to define
default WWR percent for various building types if
actual WWR is not known. Allocate percent windowto-wall ratio, by orientation if known, evenly distributed if not.
2.8 Internal loads (people, equipment, and lighting).
If known, allocate by program area. If unknown, distribute evenly over the conditioned area. Lighting
power densities should be the maximum allowed by
applicable local energy code. If unknown, use applicable local energy code or Standard 90.1 User’s Manual, Appendix G tables, for schedules, equipment
power, and occupant densities. Additional information on internal loads and schedules may be found in
NREL/TP-5500-46861 Appendices A and B.
2.9 Ventilation shall be in accordance with applicable
local building codes, ASHRAE Standard 62.1, outside
air rate per occupant, or ASHRAE/ASHE Standard
170 air change rate by usage, whichever is largest.
2.10 Perimeter/core zoning. Perimeter zone depth shall
be no greater than 1.5 times floor to floor height.
2.11 Building envelope assemblies shall be in accordance
with the applicable local building codes or the baseline performance of ASHRAE/IES Standard 90.1,
Table G3.1.5.
2.12 ASHRAE/IES Standard 90.1, Appendix G, baseline
HVAC system type is only to be used when sufficient
information on the HVAC system has not been provided to the energy modeler. Refer to Appendix C,
Section 2.1.
13
This appendix is not part of this standard. It is merely informative and does not contain requirements necessary for conformance to the standard. It has not been processed according to the ANSI requirements for a standard and may contain
material that has not been subject to public review or a consensus process. Unresolved objectors on informative material
are not offered the right to appeal at ASHRAE or ANSI.
INFORMATIVE APPENDIX D
OWNER’S PROJECT REQUIREMENTS
Per Section 5.6.1, the owner’s project requirements (OPR) shall be defined at an early stage of design. Table D-1 provides a list
of suggested energy performance categories to be addressed in the OPR. For each category, one or more recommended metrics
have been provided. This list is not intended to be exhaustive, nor are all metrics applicable to all designs.
Table D-1 Owner’s Project Requirements (OPR)
Overall Energy Budget
Energy Use Intensity (EUI)
kBtu/ft2·yr (GJ/m2·yr)
Building Envelope
Walls, roof, and floors
Assembly U-factor
Below-grade walls and slabs
Assembly U-factor, F-factor
Infiltration
cfm/ft2 ([m3/s]/m2) of building envelope area @ 0.2 in. of water (50 Pa) or
0.3 in. of water (75 Pa)
Windows
U-value, SHGC, VLT, LSG ratio
Daylighting
Spatial daylight autonomy
Percent of annual hours
Contrast
Maximum to minimum illuminance ratio
Direct solar
Annual sunlight exposure (IES LM-82), sun cutoff angle
Lighting and Equipment Power Density
Lighting (LPD)
W/ft2 (W/m2)
Light levels
Footcandles for each space function
Exterior lighting
Percent of the ASHRAE/IES Standard 90.1 allowance, W/lin ft (W/lin m),
W/ft2 (W/m2)
Plug loads
W/ft2 (W/m2)
Plumbing
Faucets and showers
gpm (L/s) @ 60 psi (414 Pa)
Toilets and urinals
gpf ([L/s]/flush)
Water heating efficiency
EF, %, COP
Loop design
Riser locations, recirculation vs. no recirculation, booster pumps
HVAC
Cooling
14
Design conditions
Assumptions and implications
Peak load
ft2/ton (m2/kW)
Efficiency
kW/ton, SEER, EER, IEER, COP, IPLV
Hydronic loop flow
gpm/ton ([L/s]/kW), loop T
Cooling towers
gpm/hp ([L/s]/kW)
ANSI/ASHRAE Standard 209-2018
Table D-1 Owner’s Project Requirements (OPR) (Continued)
HVAC (contd.)
Natural cooling
Percent of floor area, hours of year
Heating
Design conditions
Assumptions and implications
Peak load
Btu/ft2 (J/m2)
Efficiency
AFUE, EF, %, HSPF, COP
Hydronic loop flow
Loop T, °F (°C)
Heat recovery
Percent of design or overall annual
Fans
Efficiency
hp/cfm (W/[L/s]) or W/cfm (W/[L/s])
Design flow
cfm/ft2 ([L/s]/m2) of floor area, cfm/ton ([L/s]/kW)
Ventilation
Standard
ASHRAE Standards 62.1 and 62.2, IMC, Title 24
Design criteria
Number of occupants by space function, zone and system ventilation efficiency, %
oversized, Ev > Ez, ppm CO2 limit
Controls
CO2 and occupancy sensors
Energy recovery
Sensible/latent effectiveness, % summer, % winter
Natural ventilation
Percent of floor area, hours of year
Controls
Occupied/unoccupied schedules and temperature set points, humidity range
Thermal comfort
Hours set point not met, operative temperature
Other
Renewables
ANSI/ASHRAE Standard 209-2018
Photovoltaics, solar water heating
15
This appendix is not part of this standard. It is merely
informative and does not contain requirements necessary
for conformance to the standard. It has not been processed according to the ANSI requirements for a standard
and may contain material that has not been subject to
public review or a consensus process. Unresolved objectors on informative material are not offered the right to
appeal at ASHRAE or ANSI.
Internal Loads
•
•
•
•
INFORMATIVE APPENDIX E
QUALITY ASSURANCE AND
QUALITY CONTROL CHECKLISTS
This appendix provides example quality assurance (QA) and
quality control (QC) input and output checklists to support
meeting the intent of Sections 5.7.4 and 5.7.5. Documentation
templates and other QA and QC resources are provided at the
end of this appendix.
Example QA Input Checklist
Project and Building Level
•
•
•
•
•
•
•
•
•
Energy performance goals
Utility rates
Weather file data, annual and monthly values as appropriate (see Section 5.3.1)
Gross building area
Conditioned building area
Floor area by space type
Number of floors
Floor-to-floor height
Thermal blocks
Envelope
•
•
•
•
16
Roof by level—description of construction, area U-value,
emissivity, reflectivity
Wall assemblies—description of layers, total area,
opaque wall area, location, U-value, infiltration modeling
approach, infiltration rate
Fenestration—frame type, VLT, SHGC, U-value center
of glass, U-value assembly, area, percent glazing, exterior shading, interior shading
Ground contact assemblies
•
Occupant density—building average, total number of
occupants, ft2/program occupants
Lighting density—building average, density by space
type
Equipment power density—building average, density by
space type
Elevator energy and use—power demand, energy use,
number
Ventilation and exhaust rates—cfm/person, cfm/ft2 total
and by zone type
External Loads
•
Exterior lighting
HVAC Equipment
•
•
•
•
•
•
•
Temperature set points—heating/cooling set points for
each zone
Air-side system units—supply cfm, outdoor air cfm, supply temperature set point, supply fan power, flow control,
minimum flow ratio, return fan cfm, return fan power,
return fan flow control, heat recovery type/effectiveness/
power consumption/capacity control
Exhaust fans—kW, schedule
Cooling equipment—capacity, efficiency, part-load performance
Water-source heat pumps—configuration (open/closed
loop), capacity, efficiency varying by condenser water
temperature, supply water temperature, loop T
Pumps—bhp, gpm, head, capacity control, minimum
flow ratio
Domestic hot water—efficiency, hot-water supply temperature, storage tank size, storage tank UA
Plant Equipment
•
•
Efficiency, capacity, part-load performance
Process chilled- and hot-water loads—peak load and load
profile
Schedules
•
By space type for weekdays, weekends, and holidays—
occupancy, cooling and heating set points, lighting, plug
loads
ANSI/ASHRAE Standard 209-2018
Example Model Output Checklist
Use the following checklists to compare model outputs to design values and/or benchmark values to verify correctness or reasonableness. In addition, compare output results between design alternatives.
Project and Building Level
Metric
Units
Energy cost index (ECI)
$/ft2 ($/m2)
Energy use intensity (EUI)
kBtu/ft2 (GJ/m2)
Cooling capacity
ft2/ton (m2/W)
Heating capacity
Btu/(h·ft2) (J/h·m2)
Supply airflow
cfm (L/s)
Supply airflow density
cfm/ft2 (L/s·m2)
Outdoor air ventilation rate
cfm (L/s)
Outdoor air ventilation rate fraction
Fraction
Outdoor air ventilation rate per person
cfm/person (L/s·person)
Number of people
Number
Lighting
W/ft2 (W/m2)
Task lights
W/ft2 (W/m2)
Miscellaneous internal loads
W/ft2 (W/m2)
Weather file
Altitude
ft (m)
Orientation
Conditioned floor area
ft2 (m2)
Floor area by space type
ft2 (m2)
Annual peak electric load
W/ft2 (W/m2)
Electric energy
kBtu/ft2 (GJ/m2)
Fuel energy
kBtu/ft2 (GJ/m2)
Electric end-use energy
kBtu/ft2 (GJ/m2)
Fuel end-use energy
kBtu/ft2 (GJ/m2)
Other energy sources (e.g., chilled water)
kBtu/ft2 (GJ/m2)
Unmet cooling hours
hours/yr
Unmet heating hours
hours/yr
System Level Checklist
Metric
Units
Floor area served by each system
ft2 (m2)
Outdoor air fraction
Ratio
Cooling capacity
tons (kW)
Sensible heat ratio
Ratio
Heating capacity
kBtu/h (kW)
Supply airflow
cfm (L/s)
Fan power
kW
Maximum cooling load
kBtu/h (kW)
Maximum heating load
kBtu/h (kW)
Free cooling/economizer hours
Hours
ANSI/ASHRAE Standard 209-2018
17
Plant Level Checklist
Metric
Units
Peak cooling load
kBtu/hr (kW)
Peak heating load
kBtu/hr (kW)
Cooling equipment capacity
Ton (kW)
Cooling equipment total annual load
kBtu (GJ)
Cooling equipment electricity use
kWh
Cooling equipment efficiency
kW/ton
Run hours cooling equipment
Hours
Heating equipment capacity
kBtu/hr (kW)
Heating equipment total annual load
MMBtu (GJ)
Heating equipment energy use
kBtu (GJ)
Heating equipment average efficiency
%
Run hours heating equipment
Hours
SWH equipment capacity set point
kBtu/h (kW)
SWH equipment total annual load
MMBtu (GJ)
SWH equipment energy use
kBtu (GJ)
SWH equipment average efficiency
%
18
ANSI/ASHRAE Standard 209-2018
Additional Resources
Some of the materials listed below have been developed by practitioners and have not been formally vetted by the modeling
community. Table E-1 provides links to materials to support developing, documenting, and checking model input values.
Table E-2 provides links to materials to support documenting and checking output for reasonableness.
Table E-1 Documentation Templates and Quality Assurance Checklists for Model Input
Name
Source
Description
LEED EAc1, Section
1.4 Tables
SevenGroup for the
USGBC
The spreadsheets assist the energy modeler in developing and documenting the ASHRAE/
IES Standard 90.1, Appendix G, building energy model inputs. Designed to be completed
before developing the model, the forms support input quality control checks.
Sample Energy Model
Assumptions Tracking
Log
SERA Architects
Supports the documentation of design data that underlie model input values. Also includes
“schedules” tab for graphically depicting values and “outputs” tab for recording results to
support accountability.
Model Input
Development
Spreadsheet
RMI
Supports the calculation and documentation of model input values from design data. Some
values are tied to ASHRAE/IES Standard 90.1, Appendix G, procedures.
Example Building
RMI
Model eQUEST/DOE-2
Checklist
A checklist to support quality assurance checking of a whole-building simulation model.
Some of the items are eQUEST specific. https://www.rmi.org/our-work/buildings/
pathways-to-zero/deep-retrofit-tools-resources
COMNET Appendix B
Modeling Data
COMNET
Provides reasonable input values for plug loads by building and space type along with other
data to support assigning model inputs values early in the design process.
Advanced Energy
Modeling for LEED
USGBC
Provides quality control checklists for both modeling inputs and outputs, particularly when
creating a baseline model in accordance with ASHRAE/IES Standard 90.1, Appendix G.
http://www.usgbc.org/Docs/Archive/General/Docs7795.pdf
Table E-2 Documentation Templates and Quality Assurance Checklists for Model Output
Name
Source
Description
Example Building
RMI
Model eQUEST/DOE-2
Checklist
A checklist to support quality assurance checking of a whole-building simulation model.
Some of the items are eQUEST specific. https://www.rmi.org/our-work/buildings/
pathways-to-zero/deep-retrofit-tools-resources
eQUEST Quality
Control Checklists
Jeff Hirsch and
Associates
Outlines general quality assurance principles and suggests values to check in DOE-2 output
reports.
Office Building
Benchmark Values
IBPSA-USA BEM
Library
Lists typical values of key performance metrics typical for a large office building. Three
categories of efficiency are considered: inefficient existing, efficient, and low-energy.
http://www.bemlibrary.com
Building Performance
Metrics
James Waltz
From Waltz’s book, Computerized Building Energy Simulation Handbook.
http://www.rmi.org/Content/Files/WaltzGuide.pdf
Recommended Metrics
for QC Benchmarking
IBPSA-USA BEM
Library
A list of parameters helpful for completing quality control checking of model input and
output values. Practitioners can consider including them as part of their QC tools.
Developers can consider having software calculate and report these values.
ANSI/ASHRAE Standard 209-2018
19
This appendix is not part of this standard. It is merely
informative and does not contain requirements necessary
for conformance to the standard. It has not been processed according to the ANSI requirements for a standard
and may contain material that has not been subject to
public review or a consensus process. Unresolved objectors on informative material are not offered the right to
appeal at ASHRAE or ANSI.
INFORMATIVE APPENDIX F
INFORMATIVE REFERENCES
AIA. 2012. Architect’s Guide to Integrating Energy Modeling
in the Design Process. Washington, DC: American Institute of Architects. http://www.aia.org/practicing/
AIAB097932.
ASHRAE. 2015. ANSI/IES/ASHRAE 100, Energy Efficiency
in Existing Buildings. Atlanta: ASHRAE.
ASHRAE. 2016. ANSI/ASHRAE 62.1, Ventilation for
Acceptable Indoor Air Quality. Atlanta: ASHRAE.
ASHRAE. 2016. ANSI/ASHRAE 62.2, Ventilation for
Acceptable Indoor Air Quality in Residential Buildings.
Atlanta: ASHRAE.
ASHRAE. 2017. ANSI/ASHRAE/ASHE 170, Ventilation of
Health Care Facilities. Atlanta: ASHRAE.
ASHRAE. 2017. ASHRAE Building Energy Modeling Professional (BEMP) Certification Candidate Guidebook.
Atlanta: ASHRAE.
ASHRAE. 2017. 2017 ASHRAE Handbook—Fundamentals,
Chapter 19, “Energy estimating and modeling methods.”
Atlanta: ASHRAE.
CIBSE. 2015. Applications Manual 11, Building Performance Modelling. London: Chartered Institution of
Building Services. http://www.cibse.org/knowledge/
cibse-am/am11-building-performance-modelling-new2015.
Clarke, J.A. 2001. Energy Simulation in Building Design,
2nd ed. Oxford: Butterworth-Heinemann.
Clayton, M.; J. Haberl; W. Yan; S. Kota; F. Farias; W.-S.
Jeong; J. Kim; and J.L.B. Alcocer. 2013. Development of
a Reference Building Information Model (BIM) for Thermal Model Compliance Testing. ASHRAE Research
Project 1468 Final Report. Atlanta: ASHRAE.
Dunn, J., L. Hemley, G. Gladics, and E. Djuaedy. 2013. UI-IDL
building simulation protocols v. 1.0 DRAFT. Boise, ID: University of Idaho Integrated Design Lab. https://sites.google.com/site/idlbsug/modeling-resources/ui-idl-simulationprotocols-draft.
Energy Design Resources. 2010. Design Guidelines: Advanced
Simulation Guidebook, Volume II. San Francisco, CA: California Public Utilities Commission. https://energydesignresources.com/media/2299/
EDR_DesignGuidelines_Advanced_Simulation_Vol2.pdf.
EVO. 2006. International Performance Measurement and
Verification Protocol Applications Volume III, Part I:
Concepts and Practices for Determining Energy Savings
in New Construction. EVO 30000-1:2006. Washington,
DC: Efficiency Valuation Organization.
Franconi, E. 2011. Introducing a framework for advancing
building energy modelling methods & processes. Pro20
ceedings of Building Simulation 2011: 12th Conference
of International Building Performance Simulation Association, Sydney, 14–16 November.
Fuller, S.K., S.R. Petersen, and R.T. Ruegg. 1996. Life-Cycle
Costing Manual for the Federal Energy Management
Program. Gaithersburg, MD: National Institute of Standards and Technology.
Hensen, J., and R. Lamberts. (Eds.) 2011. Building Performance Simulation for Design and Operation. Abingdon,
Oxon: Routledge.
Hotchkiss, E., A. Walker, and N. Carlisle. 2012. Procuring
Architectural and Engineering Services for Energy Efficiency and Sustainability: A Resource Guide for Federal
Construction Project Managers. DOE/GO-102012-3292
Golden, CO: National Renewable Energy Laboratory.
IBPSA-USA. BEMBook wiki. International Building Performance Simulation Association—USA Affiliate.
IES. 2012. IES LM-82, Characterization of LED Light
Engines and LED Lamps for Electrical and Photometric
Properties as a Function of Temperature. New York: Illuminating Engineering Society.
Kaplan, M., and P. Caner. 1992. Guidelines for Energy Simulation of Commercial Buildings. DOE/BP/26683--2
DE92 015597. Portland, OR: Bonneville Power Administration.
Kota, S., F. Farias, W. Jeong, J. Kim, J.B. Alcocer, M.J. Clayton, W. Yan, and J.S. Haberl. 2016. Development of a
reference building information model (BIM) for thermal
model compliance testing (RP-1468) Part I: Guidelines
for generating thermal model input files. ASHRAE Transactions 1(122):256–66.
McCarry, B., and L. Montague. 2010. Guidelines for energy
analysis integration into an architectural environment.
Perkins & Will Research Journal 2 (2):72–96.
Nall, D. H, and D.B. Crawley. 2011. Hall of fame: Energy
simulation in the building design process: Mainframe
computer simulation programs for energy analysis can
provide important information throughout the building
design process. ASHRAE Journal 53(7):36–43.
NREL. 2011. U.S. Department of Energy Commercial Reference Building Models of the National Building Stock.
NREL/TP-5500-46861, National Renewable Energy Laboratory, Lakewood, CO.
USDOE. 2015. Energy Star multifamily high rise program
simulation guidelines. Version 1.0, Revision 03 January
2015. Washington, DC: United States Department of
Energy.
USDOE. 2001. Low-Energy Building Design Guidelines.
DOE/GO-102001-0950; DOE/EE-0249 NREL/BK-71025807. Golden, CO: National Renewable Energy Lab.
USGBC. 2011. Advanced Energy Modeling for LEED Technical Manual v.2.0. Washington, DC: United States Green
Building Council. http://www.usgbc.org/resources/
advanced-energy-modeling-leed-technical-manual-v20.
Waltz, J.P. 2000. Computerized Building Energy Simulation
Handbook. Lilburn, GA: Fairmont Press.
Washington State Department of Enterprise Services Division
of Engineering and Architectural Services. 2013. Energy
Life Cycle Cost Analysis. Washington State Department
of Enterprise Services, Olympia, WA.
ANSI/ASHRAE Standard 209-2018
POLICY STATEMENT DEFINING ASHRAE’S CONCERN
FOR THE ENVIRONMENTAL IMPACT OF ITS ACTIVITIES
ASHRAE is concerned with the impact of its members’ activities on both the indoor and outdoor environment.
ASHRAE’s members will strive to minimize any possible deleterious effect on the indoor and outdoor environment of
the systems and components in their responsibility while maximizing the beneficial effects these systems provide,
consistent with accepted Standards and the practical state of the art.
ASHRAE’s short-range goal is to ensure that the systems and components within its scope do not impact the
indoor and outdoor environment to a greater extent than specified by the Standards and Guidelines as established by
itself and other responsible bodies.
As an ongoing goal, ASHRAE will, through its Standards Committee and extensive Technical Committee structure,
continue to generate up-to-date Standards and Guidelines where appropriate and adopt, recommend, and promote
those new and revised Standards developed by other responsible organizations.
Through its Handbook, appropriate chapters will contain up-to-date Standards and design considerations as the
material is systematically revised.
ASHRAE will take the lead with respect to dissemination of environmental information of its primary interest and
will seek out and disseminate information from other responsible organizations that is pertinent, as guides to updating
Standards and Guidelines.
The effects of the design and selection of equipment and systems will be considered within the scope of the
system’s intended use and expected misuse. The disposal of hazardous materials, if any, will also be considered.
ASHRAE’s primary concern for environmental impact will be at the site where equipment within ASHRAE’s scope
operates. However, energy source selection and the possible environmental impact due to the energy source and
energy transportation will be considered where possible. Recommendations concerning energy source selection
should be made by its members.
ASHRAE · 1791 Tullie Circle NE · Atlanta, GA 30329 · www.ashrae.org
About ASHRAE
ASHRAE, founded in 1894, is a global society advancing human well-being through sustainable technology for the
built environment. The Society and its members focus on building systems, energy efficiency, indoor air quality,
refrigeration, and sustainability. Through research, Standards writing, publishing, certification and continuing
education, ASHRAE shapes tomorrow’s built environment today.
For more information or to become a member of ASHRAE, visit www.ashrae.org.
To stay current with this and other ASHRAE Standards and Guidelines, visit www.ashrae.org/standards.
Visit the ASHRAE Bookstore
ASHRAE offers its Standards and Guidelines in print, as immediately downloadable PDFs, on CD-ROM, and via
ASHRAE Digital Collections, which provides online access with automatic updates as well as historical versions of
publications. Selected Standards and Guidelines are also offered in redline versions that indicate the changes made
between the active Standard or Guideline and its previous version. For more information, visit the Standards and
Guidelines section of the ASHRAE Bookstore at www.ashrae.org/bookstore.
IMPORTANT NOTICES ABOUT THIS STANDARD
To ensure that you have all of the approved addenda, errata, and interpretations for this
Standard, visit www.ashrae.org/standards to download them free of charge.
Addenda, errata, and interpretations for ASHRAE Standards and Guidelines are no
longer distributed with copies of the Standards and Guidelines. ASHRAE provides
these addenda, errata, and interpretations only in electronic form to promote
more sustainable use of resources.
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