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Shane Nault, PE, CEM, CxA, LEED AP BD+CPresidentBuilding EnergetiCx, PLLC
Building Energy Simulation
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.
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.
Course Description
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.
Learning Objectives
Where Are Building Energy Simulations Required?
• EAp2 – Energy and Atmosphere Prerequisite 2 – Minimum Energy Performance (AHRAE 90.1-2007)
• EAc1 – Energy and Atmosphere Credit 1 – Optimize Energy Performance
LEED® Rating System
• Not required, but may be necessary to evaluate energy saving opportunities• Compare Energy Conservation Measures (ECMs)
Energy Assessments / Existing Building Cx
• Compare proposed design to ASHRAE Standard 90.1 baseline (% Improvement)• IECC 2012 – Total Building Performance (IGCC)
State Regulations / Building Codes
• 50% greater energy efficiency standard than ASHRAE Standard 90.1-2001• Can model building envelope, HVAC, and Lighting individually
179d - Energy Efficient Commercial Bldg Deduction
Building Energy Simulation
What is It?
• Input Variables (Climate)• System parameters /
properties (building)• Output (Energy Use)
• Input Variables (Climate)• System parameters /
properties (building)• Output (Energy Use)
Uses a “mathematical
model as a description of a behavior of a
system”
• Output Reports / Data• Building Loads• Energy Consumption• Economic Analysis
• Output Reports / Data• Building Loads• Energy Consumption• Economic Analysis
Simulation using software to estimate
end-use energy usage and demand
Energy Simulation Perspectives
Data-Driven Simulation• Existing Buildings• Develop Baseline
Forward Simulation• Design Based• Prediction of future
Two Approaches
Benefits of Building Energy Simulations
Benefits
Decision Based
Design Tool
Prediction of Energy Usage
Comparison Tool
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
Software Comparison
DO
E 2.
2
Ener
gy
Gau
ge
Ener
gy
Plus
eQue
st
HA
P
IES
VE-P
ro
Trac
e 70
0
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
Graphical Input 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
Cost Free/$650 $949 Free Free $1,495 $3,000 $1,995(1) Through third party software(2) Developing now.(3) Partial
Other Simulation Software
• Web-Based Energy Analysis Software• Whole Building Energy Analysis• Integrates with Revit (gbXML)• Evaluates Natural
Ventilation• Provides ENERGY
STAR® Score• Water Usage
Autodesk Green Building Studio
Other Simulation Software
• Sustainable Building Design Software
• Visualization Tool• Thermal Performance• Daylighting• Shadows• Solar Radiation• PV Collection
Ecotect Analysis
Energy Simulation Principles
1. Reduce Load
2. Harvest Site Attributes
3. Recover Waste Energy
4. Improve System Efficiency
Load Analysis - Location
Project Location
Thermal Zone
Weather Library• Temperatures (dry-
bulb / 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• Density• Activity
Level
Lights• Lighting
Power Density
• Internal / External
Equipment• Plug Loads• Process
Loads
Load Analysis - Ventilation
Ventilation and Exhaust Requirements• ASHRAE Standard 62.1
Occupancy CFM / Person
CFM / sf # / 1000 sf
Lecture Classroom 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
Load Analysis - Behavior
Schedules• Overall Building• Occupancy• Misc. Equipment• Lighting• Thermostats• HVAC Systems
Environmental Requirements• Temperature /
Humidity
Typical Building Loads
Building TypeCooling Load (sf/ton)
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 Rooms2. 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• Water to
Water• Air to Air• Air to Water
Control Strategies• Night Set
Back• Demand
Control Ventilation
Plant Analysis
• Chilled Water, Heating Water, Steam, Geothermal, Dx
Equipment Type (Source)
• Electric, Gas, Water, Purchased
Fuel Type
• Efficiencies
Performance Characteristic
Load Assignment
Economic Analysis
Utility Rate Structures
Economic Factors• Interest Rates ( Tax / Inflation)
Economic Costs• First Cost, Maintenance Cost, Replacement Cost
Life Cycle Analysis
Developing the Baseline
Establish BaselineMeasureable
• 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 87,000Btu/sf-yr
75,195Btu/sf-yr
ECI $1.48 /sf $1.36 /sf
Baseline Energy Simulation
Load Analysis
Systems Analysis
Plant Analysis
Economic Analysis
Verify Building Operation Schedule
Verify Control Strategies
Observe Plug Loads
Verify Utility Rate Schedule
Energy Simulation - Accuracy
+10% -10%
Compare Baseline Simulation to Actual(This May Take Several Iterations)
Energy Conservation Measures
ECM Description Cost Potential Savings
Simple Payback Priority
C1 Occupancy Schedules 1 1 1 1C2 Hot Water Reset 1 1 1 1C3 Economizer 1 1 1 1C4 SAT Reset 1 1 1 1H1 Replace CT 3 2 2 2H2 Add VFD 2 1 1 1
Alternative Evaluations
• Build Alternatives (one at a time)• Compare Energy Usage• Economic Analysis
ECM Cost EnergySavings
Cost Savings
Simple Payback Priority
C1 $1,500 106,607 kWh $8,078 0.2 Yrs 1C7 $1,000 83,757 kWh $6,332 0.2 Yrs 1H6 $500 3,374 kWh $255 1.9 Yrs 1W1 $850 43,928 gal $515 1.7 Yrs 1L1 $2,350 6,224 kWh $471 4.2 Yrs 1
Measurement and Verification
Continuous Performance Monitoring
Proactive Energy Management
Operational Training
Accountability
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
•Refine model and systems
Construction Document
•Finalize Comparison
Project Decision Points
39
Predesign SchematicDesign
ConstructionDocuments
Agency Permit /Bidding
ConstructionDesignDevelopment
Project ProgressD
esig
n Ef
fort
/Effe
ct
Graphic originated by Patrick MacLeamy, FAIA
1
2
Ability to impact cost and functional
capabilities1
2 Cost of design changes
LEED® Categories
LEED®
Sustainable Sites (SS)
Water Efficiency
(WE)
Energy and Atmosphere
(EA)
Materials and Resources
(MR)
Indoor Environmental Quality (IEQ)
Innovation in Design (ID)
Regional Priority (RP)
LEED® NC 2009 vs. LEED® NC 2.2
LEED® NC 2.2 LEED® NC 2009 Diff%Description Possible % of
TotalPossible % 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% 7.2Materials and Resources (MR) 13 18.8% 14 12.7% -6.1
Indoor Environmental Quality (IEQ)
15 21.7% 15 13.6% -8.1
BONUS POINTSInnovative 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%
LEED® NC 2012 vs. LEED® NC 2009
LEED® NC 2009 LEED® NC 2012 Diff%Description Possible % of
TotalPossible % 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% -1.8Materials 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
TOTALS 110 100% 110 100% 0
LEED® NC Certification Requirements
LEED NC 2.2 LEED NC 2009 / 2012Level Lower Upper Lower Upper
Certified 26 32 40 49Silver 33 38 50 59Gold 39 51 60 79Platinum 52 69 80 110
LEED® Energy and Atmosphere – EAp2
• Establish Minimum Level of Energy Efficiency
Intent
• Comply with ASHRAE Standard 90.1 - 2007• Demonstrate a 10% Minimum Energy
Reduction Compared to ASHRAE Standard 90.1 - 2007 Compliant Building
Requirements
LEED® Energy and Atmosphere – EAc1
• 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)
Optimize Energy Performance
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
• Building envelopeSection 5• Heating, ventilation, and
air-conditioningSection 6• Service water heatingSection 7• PowerSection 8• LightingSection 9• Other equipmentSection 10
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
Variables
Building Size
Alternatives / Iterations
Systems (Quantity /
Type)
Information Availability
Wrap Up
Summary
Powerful Decision
Making ToolThroughout
project
Data CentricMany Input
Choices and Decisions
ECM Evaluation
LEED Energy Simulation
Shane Nault, PE, CEM, CxA, LEED AP BD+C
E-Mail: [email protected]
Website: www.buildingenergeticx.com