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

Basic System

Architect

Engineer

Owner

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

Energy Plus

Free ToolGraphical Interface

OpenStudio

Google SketchUp

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

Energy Simulation Process

Load Analysis

Systems Analysis

Plant Analysis

Economic Analysis

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

Data Driven Simulations

Existing Building Commissioning

ECM EvaluationMeasurement and

Verification

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

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

•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® Rating Systems

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

Questions / Comments

Save your QuestionsWe 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