Assessing Your Building Energy Costs:

Benefits of Energy Modeling to Owners

Keith SwartzEnergy Center of Wisconsin

ComEd New Construction ProgramNicor New Construction Program

Illinois ASHRAE Modeling ConferenceFebruary 14, 2012

Energy Modeling for Owners

Building Energy Model Basics

Reasons to do a Building Energy Model

Selecting an Energy Modeler

Information Exchange with the Modeler

Economic Analysis and Decision Making

Building Energy Model Basics A computer simulation that estimates

the energy use and energy cost of a building

Simple or complex Accounts for system interactions Existing or new building

Building Energy Model Basics

Limitations No program is perfect Many inputs are assumed Only an estimate Does not make decision for you

Energy Modeling for Owners

Building Energy Model Basics

Reasons to do a Building Energy Model

Selecting an Energy Modeler

Information Exchange with the Modeler

Economic Analysis and Decision Making

Why Do an Energy Model? Provide information for a decision

Often energy cost savings for potential upgrades

Prevent bad decisions based on bad hunches

Determine number of LEED® credits Documentation for tax credit Identify where your energy dollars

are going Estimate future energy use or cost

Why Not Do an Energy Model?

Low-energy building Small Simple

Energy not a concern Insufficient time in project schedule No local qualified energy modelers

Energy Modeling for Owners

Building Energy Model Basics

Reasons to do a Building Energy Model

Selecting an Energy Modeler

Information Exchange with the Modeler

Economic Analysis and Decision Making

Selecting an Energy Modeler

Where to find an energy modeler• Architectural firm• Engineering firm• Energy consulting firm (ESCO)• Sustainable building consultant• Independent modeling consultant• Utility

Be very specific in the contract

Selecting an Energy Modeler

What to look for in an energy modeler• Knowledge of buildings• Knowledge of the software used• Quality control procedures• ASHRAE certification as a Building Energy

Modeling Professional (BEMP)• Can generate energy saving ideas

Selecting an Energy Modeler

What to look for in an energy modeler• Able to communicate and summarize• Flexibility with deliverables• LEED modeling experience (if applicable)• Construction cost estimating (optional)• Financial analysis (optional)

Energy Modeling for Owners

Building Energy Model Basics

Reasons to do a Building Energy Model

Selecting an Energy Modeler

Information Exchange with the Modeler

Economic Analysis and Decision Making

Info Modeler Needs from You

Reason for doing the energy model Deliverable Location of the building People Lights Plugged in equipment HVAC systems

Info Modeler Needs from You

Building drawings Utility rates List of options to evaluate For existing buildings add

• As much detail as possible on the above items

• Past utility bills, 3 years• Submeter data (if any)

Info You Need from Modeler

Depends on why the model was done The deliverable

Info You Need from Modeler

Other questions to ask• How do the results compare to similar

buildings?• What were the major assumptions?• For existing buildings…

How close does the model match utility data? Was actual weather data used or “typical” year?

Energy Modeling for Owners

Building Energy Model Basics

Reasons to do a Building Energy Model

Selecting an Energy Modeler

Information Exchange with the Modeler

Economic Analysis and Decision Making

Economic Analysis Who will do the economic analysis? What is the acceptance criteria?

• Simple payback Consider how long until the component will be

replaced• ROI• Life cycle cost – best for long-term

economics Use appropriate life cycle period for each

component

Economic Analysis Factors to consider

• Energy cost savings (from the energy model)• Cost to implement the upgrade• Maintenance cost savings• Reduced investment due to smaller

heating/cooling equipment• Inflation• Discount Rate• Tax benefits• Utility rebates / incentives• Years to component replacement

Economic Analysis Uncertainty of implementation cost

Get quotes Be careful using a crude estimate in the

analysis Consider determining the present value of

future savings – “break-even” cost Easy to compare to an uncertain

implementation cost when bids come in If the bid is less than the break-even

cost, then the upgrade is beneficial

Economic Analysis Consider checking sensitivity

Energy cost savings estimates and implementation costs are uncertain

Check a range of values

Energy Modeling for Owners

Building Energy Model Basics

Reasons to Do a Building Energy Model

Selecting an Energy Modeler

Information Exchange with the Modeler

Economic Analysis and Decision Making