Energy Modeling: The Basics

by: Mischa Bowen-Kreiner

What is an energy model?

An energy model is a computer based simulation of an actual, or proposed, building and can provide an estimate of the building’s energy usage throughout a typical year.  The virtual replica of the building is constructed from its component parts, including air conditioners, heaters, lights, and other energy loads, and is run through a simulation program with weather conditions for a full year to estimate the building’s monthly, and total, energy costs.  Energy models are commonly divided in to two categories, Load Design, and Energy Analysis.  Load Design is used to determine how large a building’s HVAC (Heating, Ventilation, and Air Conditioning) components must be to keep its occupants comfortable.  Energy Analysis is used to predict the monthly and yearly energy consumption, monthly and yearly energy costs, and to determine life cycle costs associated with building components.  An energy model is an extremely valuable tool for helping to determine how and where a building’s energy is being used, and as a result, can determine how and where energy consumption can be reduced.

Which energy modeling program should I use?

There are many different programs available, each with its own strengths and weaknesses.  The US Department of Energy, currently lists over 400 Building Energy Software tools!  The functionality, level of intuitiveness, and customer support for each of the programs varies greatly and it is recommended that you do a little research before you select which program you want to use.  Some programs are very broad in nature and will be able to perform a wide variety of calculations, while others are much more focused in their scope.  The most commonly used energy modeling programs include Trane TRACE 700, Carrier HAP, eQUEST, and EnergyPlus. These programs are generally more robust, and better suited to the complete energy modeling process.  They also tend to have better customer support networks and help features.  Which energy modeling program you choose will ultimately come down to what you want to use the program for, what types of features you are looking for, and personal preference.

Who needs an energy model?

Everyone!  Performing an energy model is a great way to find out how much energy a building consumes, and which mechanical components are using the most energy.  Energy modeling is most beneficial in the design phase of new building construction, but can be useful for an existing building as well.  Running a planned building through an energy model can let engineers, architects, and designers see the effects of design changes on a building’s energy consumption.  This allows them to make smart choices regarding building layout, component selection, and environmental impact.   Running an existing building through an energy model can show the owners and occupants where their energy dollars are going and where building improvements can be made to help reduce energy usage and cost.

Have questions? Please let us know; we’d be happy to help! Thank you and happy modeling!

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