Building Energy Simulation
Shane Nault, PE, CEM, CxA, LEED AP BD+C
President
Building EnergetiCx, PLLC
AIA Quality Assurance
The Building Commissioning Association is a Registered Provider with
The American Institute of Architects Continuing Education
Systems (AIA/CES). Credit(s) earned on completion of this program
will be reported to AIA/CES for AIA members. Certificates of
Completion for both AIA members and non-AIA members are available
upon request.
This program is registered with AIA/CES for continuing professional
education. As such, it does not include content that may be deemed
or construed to be an approval or endorsement by the AIA of any
material of construction or any method or manner of handling, using,
distributing, or dealing in any material or product.
Questions related to specific materials, methods, and services will be
addressed at the conclusion of this presentation.
Course Description
With the increasing improvement on building energy efficiency and
Net Zero goals, building energy simulations are becoming the
standard on more projects.
This course will provide a basic understanding of the building
energy simulation process and the two basic types of
applications. We will review the energy simulation tools
available. Finally we will review some of the requirements for
LEED energy modeling.
Learning Objectives
At the end of this session, participants will be able to:
1. Participants will understand the building energy simulation
process and different software tools available.
2. Participants will be able to identify the benefits of building
energy simulation.
3. Participants will be to prepare future predictive and data
driven building energy models to evaluate system design
performance and energy conservation measures.
4. Participants will be able to navigate through the basics of
LEED building energy modeling and ASHRAE Standard 90.1
requirements.
Where Are Building Energy Simulations Required?
LEED® Rating System
• EAp2 – Energy and Atmosphere Prerequisite 2 – Minimum Energy Performance
(AHRAE 90.1-2007)
• EAc1 – Energy and Atmosphere Credit 1 – Optimize Energy Performance
Energy Assessments / Existing Building Cx
• Not required, but may be necessary to evaluate energy saving opportunities
• Compare Energy Conservation Measures (ECMs)
State Regulations / Building Codes
• Compare proposed design to ASHRAE Standard 90.1 baseline (% Improvement)
• IECC 2012 – Total Building Performance (IGCC)
179d - Energy Efficient Commercial Bldg Deduction
• 50% greater energy efficiency standard than ASHRAE Standard 90.1-2001
• Can model building envelope, HVAC, and Lighting individually
Building Energy Simulation
What is It?
Uses a
“mathematical
model as a
description of a
behavior of a
system”
• Input Variables (Climate)
• System parameters /
properties (building)
• Output (Energy Use)
•
Simulation using
software to estimate •
•
end-use energy
usage and demand •
Output Reports / Data
Building Loads
Energy Consumption
Economic Analysis
Basic System
Architect
Engineer
Owner
Energy Simulation Perspectives
Two Approaches
Data-Driven
Simulation
• Existing Buildings
• Develop Baseline
Forward
Simulation
• Design Based
• Prediction of future
Benefits of Building Energy Simulations
Decision
Based
Design Tool
Benefits
Comparison
Tool
Prediction of
Energy
Usage
Building Energy Simulation Software
DOE Qualified
Software
•
•
•
•
•
DOE-2.2
Energy Gauge
Energy Plus
eQuest
Hourly Analysis Program
(Carrier HAP)
• IES – Virtual Environment
• Trace 700 (Trane)
http://www1.eere.energy.gov/buildings/qualified_software.html
DOE
2.2
Energy
Gauge
Energy
Plus
eQuest
HAP
IES
VE-Pro
Trace
700
Software Comparison
8,760 hrs / Yr
Yes
Yes
Yes
Yes
Yes
Yes
Yes
ASHRAE 90.1
Yes
Yes
Yes
Yes
Yes
Yes
Yes
> 10 Zones
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Hourly Loads
Yes
Yes
Yes
Yes
Yes
Yes
Yes
CAD Import
No
No
Yes
Yes
Yes
Yes
Yes
eQuest
No
Yes(1)
Yes
No
Yes
No
Graphical Reports
No
No
No
Yes
Yes
Yes
Yes
Automatic LEED
Baseline
No
Yes
No
No
No(3)
No(2)
No
LEED Reports
No
Yes
No
No
Yes
Yes
Yes
Free/$650
$949
Free
Free
$1,495
$3,000
$1,995
Graphical Input
Cost
(1) Through third party software
(2) Developing now.
(3) Partial
Energy Plus
Free Tool
Graphical Interface
OpenStudio
Google SketchUp
Other Simulation Software
Autodesk Green Building Studio
•
•
•
•
Web-Based Energy Analysis Software
Whole Building Energy Analysis
Integrates with Revit (gbXML)
Evaluates Natural
Ventilation
• Provides ENERGY
STAR® Score
• Water Usage
Other Simulation Software
Ecotect Analysis
• Sustainable Building
Design Software
• Visualization Tool
• Thermal Performance
• Daylighting
• Shadows
• Solar Radiation
• PV Collection
Energy Simulation Principles
1. Reduce Load
2. Harvest Site Attributes
3. Recover Waste Energy
4. Improve System Efficiency
Energy Simulation Process
Load
Analysis
Systems
Analysis
Plant
Analysis
Economic
Analysis
Load Analysis - Location
Project Location
Thermal Zone
Weather Library
• Temperatures (drybulb / web-bulb)
• Cloud Factor
• Wind Speed
• Pressure
Load Analysis – Building Input
Building Envelope
•
•
•
•
•
Walls
Roofs
Floors
Windows / Doors
Dimensions (length,
width, height)
Building Area
• Zoning
Helpful Information
• Floor Plans, Elevations,
Sections
Load Analysis – Internal Loads
People
Lights
Equipment
• Density
• Activity
Level
• Lighting
Power
Density
• Internal /
External
• Plug Loads
• Process
Loads
Load Analysis - Ventilation
Ventilation and Exhaust Requirements
• ASHRAE Standard 62.1
Occupancy
CFM /
Person
CFM / sf
# / 1000 sf
7.5
0.06
65
Office Space
5
0.06
7
Conference / Meeting
5
0.06
50
Corridors
0
0.06
0
Storage Rooms
0
0.12
0
Lecture Classroom
Load Analysis - Behavior
Schedules
•
•
•
•
•
•
Overall Building
Occupancy
Misc. Equipment
Lighting
Thermostats
HVAC Systems
Environmental
Requirements
• Temperature /
Humidity
Typical Building Loads
Cooling Load (sf/ton)
Building Type
Low
Average
High
Education
240
185
150
Hospital1
275
220
165
Hotel
350
300
220
Office
360
280
190
Restaurant2
150
120
100
1. Patient Rooms
2. Medium
ASHRAE Pocket Guide for Air Conditioning, Heating, Ventilation, and Refrigeration - 2001
System Analysis – System Type
Variable Air Volume
Constant Air Volume
•
Others System Types Include – Chilled Beams, Displacement,
Underfloor, Induction, Fan Coil, PTAC, Heat Pumps.
System Analysis – System Options
Economizer
• Dry Bulb
• Enthalpy
Energy
Recovery
Control
Strategies
• Water to
Water
• Air to Air
• Air to Water
• Night Set
Back
• Demand
Control
Ventilation
Plant Analysis
Equipment Type (Source)
• Chilled Water, Heating Water, Steam, Geothermal, Dx
Fuel Type
• Electric, Gas, Water, Purchased
Performance Characteristic
• Efficiencies
Load Assignment
Economic Analysis
Utility Rate Structures
Economic Factors
• Interest Rates ( Tax / Inflation)
Economic Costs
• First Cost, Maintenance Cost, Replacement Cost
Life Cycle Analysis
Data Driven Simulations
Existing Building
Commissioning
ECM Evaluation
Measurement and
Verification
Developing the Baseline
Establish Baseline
Measureable
• Energy Utilization Index
(EUI)
• Energy Cost Index (ECI)
• Cost of Goods Produced
• Carbon Reduction
Building Energy Performance
Energy
Use Index
Energy
Cost Index
“We can’t manage
what we don’t
measure”
Building Energy Benchmark
Evaluate Utility
Bills
• (3 Years
Minimum)
Establish Building
Performance
• Energy Star
• CBECS
Baseline
Building
EUI
87,000
Btu/sf-yr
75,195
Btu/sf-yr
ECI
$1.48 /sf
$1.36 /sf
Baseline Energy Simulation
Load
Analysis
Systems
Analysis
Plant
Analysis
Verify Building Operation Schedule
Verify Control Strategies
Observe Plug Loads
Verify Utility Rate Schedule
Economic
Analysis
Energy Simulation - Accuracy
Compare Baseline Simulation to Actual
(This May Take Several Iterations)
+10%
-10%
Energy Conservation Measures
ECM
Description
Cost
Potential
Savings
Simple
Payback
Priority
C1
Occupancy Schedules
1
1
1
1
C2
Hot Water Reset
1
1
1
1
C3
Economizer
1
1
1
1
C4
SAT Reset
1
1
1
1
H1
Replace CT
3
2
2
2
H2
Add VFD
2
1
1
1
Alternative Evaluations
• Build Alternatives (one at a time)
• Compare Energy Usage
• Economic Analysis
ECM
Cost
Energy
Savings
Cost
Savings
Simple
Payback
Priority
C1
$1,500
106,607 kWh
$8,078
0.2 Yrs
1
C7
$1,000
83,757 kWh
$6,332
0.2 Yrs
1
H6
$500
3,374 kWh
$255
1.9 Yrs
1
W1
$850
43,928 gal
$515
1.7 Yrs
1
L1
$2,350
6,224 kWh
$471
4.2 Yrs
1
Measurement and Verification
Continuous Performance
Monitoring
Proactive Energy Management
Operational Training
Accountability
Forward Simulation
Commissioning
Providers and
Energy Simulations
Synergies with
Commissioning
When do you start the Energy Simulation?
Energy Simulation In Phases
Conceptual
Design
•Site Location
•Building
Massing
•Building
Orientation
•Comparing
Alternatives
(High Level)
•Relatively
Accurate
Schematic
Design
•Optimize Focus
•Energy Saving
Strategies
•Evaluate
Energy
Breakdown
•Where to focus
efforts
Design
Development
Construction
Document
•Refine model
and systems
•Finalize
Comparison
Project Decision Points
Project Progress
Design Effort/Effect
1
2
1
2
Predesign
Ability to impact cost
and functional
capabilities
Cost of design
changes
Schematic
Design Construction
Agency PermitConstruction
/
Design Development Documents
Bidding
39
Graphic originated by Patrick MacLeamy, FAIA
LEED® Rating Systems
LEED® Categories
Sustainable
Sites (SS)
Water
Efficiency
(WE)
Regional
Priority (RP)
LEED®
Energy and
Atmosphere
(EA)
Innovation in
Design (ID)
Indoor
Environmental
Quality (IEQ)
Materials and
Resources
(MR)
LEED® NC 2009 vs. LEED® NC 2.2
LEED® NC 2.2
Description
LEED® NC 2009
Diff
%
Possible
% of
Total
Possible
% of
Total
Sustainable Sites (SS)
14
20.3%
26
23.6%
3.4
Water Efficiency (WE)
5
7.3 %
10
9.1%
1.8
Energy and Atmosphere (EA)
17
24.6%
35
31.8%
7.2
Materials and Resources (MR)
13
18.8%
14
12.7%
-6.1
Indoor Environmental Quality
(IEQ)
15
21.7%
15
13.6%
-8.1
Innovative Design (ID)
5
7.3%
6
5.5%
-1.8
Regional Priority (RP)
0
0%
4
3.6%
3.6
TOTALS
69
100%
110
100%
BONUS POINTS
LEED® NC 2012 vs. LEED® NC 2009
LEED® NC 2009
Description
LEED® NC 2012
Diff
%
Possible
% of
Total
Possible
% of
Total
Integrative Process (IP)
-
-
1
0.9
+0.9
Location Transportation (LT)
-
-
16
14.5%
+14.5
Sustainable Sites (SS)
26
23.6%
10
9.1%
-14.5
Water Efficiency (WE)
10
9.1%
11
10%
+0.9
Energy and Atmosphere (EA)
35
31.8%
33
30%
-1.8
Materials and Resources (MR)
14
12.7%
13
11.8%
-0.9
Indoor Environmental Quality
(IEQ)
15
13.6%
16
14.5%
+0.9
Innovative Design (ID)
6
5.5%
6
5.5%
0
Regional Priority (RP)
4
3.6%
4
3.6%
0
110
100%
110
100%
0
TOTALS
LEED® NC Certification Requirements
LEED NC 2.2
Level
LEED NC 2009 / 2012
Lower
Upper
Lower
Upper
Certified
26
32
40
49
Silver
33
38
50
59
Gold
39
51
60
79
Platinum
52
69
80
110
LEED® Energy and Atmosphere – EAp2
Intent
• Establish Minimum Level of Energy Efficiency
Requirements
• Comply with ASHRAE Standard 90.1 - 2007
• Demonstrate a 10% Minimum Energy
Reduction Compared to ASHRAE Standard
90.1 - 2007 Compliant Building
LEED® Energy and Atmosphere – EAc1
Optimize Energy Performance
• Whole Building Energy Simulation (1-19 points)
• One point for every 2% reduction in energy
cost
• Base - 10% New Buildings, 8% Existing
Buildings
• Prescriptive path -ASHRAE Advanced Energy
Design Guides (1 point)
• Prescriptive path -Advanced Buildings Core
Performance Guide (1-3 points)
LEED® Simulation Ins/Outs
Baseline (ASHRAE Standard 90.1 – 2007) vs. Proposed
Percentage savings based on energy cost NOT actual energy consumption
25% of total load must be process load (or plug load)
Include site lighting, domestic hot water systems, elevators, kitchen hoods
Identify different spaces (IT Closets / Usage)
Can use state average utility rates published by the DOE
Treat existing Central Utility Plant as purchased chilled water, must be cost Neutral
Modeling a large Campus - Each building must meet LEED® independently
ASHRAE Standard 90.1 Components
Section 5
• Building envelope
Section 6
• Heating, ventilation, and
air-conditioning
Section 7
• Service water heating
Section 8
• Power
Section 9
• Lighting
Section 10
• Other equipment
ASHRAE Standard 90.1
Simulate Baseline
Baseline defined by Appendix G
Baseline systems based on building size
Must use full year weather data (8760 Hrs)
Must comply with unmet load hour requirements
Be sure to rotate the building simulation (PRM)
Schedules must be same in baseline and proposed
Energy Simulation Variables
Alternatives
/ Iterations
Systems
(Quantity /
Type)
Building
Size
Information
Availability
Variables
Wrap Up
Powerful
Decision
Making Tool
Throughout
project
Data Centric
Many Input
Choices and
Decisions
Summary
ECM
Evaluation
LEED Energy
Simulation
Questions / Comments
Save your Questions
We will respond at the conclusion of both
presentations
Shane Nault, PE, CEM, CxA, LEED AP BD+C
E-Mail: s.nault@buildingenergeticx.com
Website: www.buildingenergeticx.com