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Why Energy Models?

Posted on Sep 22, 2017 in:
  • Built Green
  • Builders
Third & Valley Rooftop Deck

Built Green 4-Star project by Denizen Development LLC

Most builders pursuing Built Green certification quickly realize that the energy model of their project is one of the keys to achieving a given star-level. Almost all Built Green star-levels for nearly all certification types (Community certification and Refit certification being the exceptions) require an energy model.

How does this work? Why is this the case? Let us explain.

What is an energy model?

An energy model is a projection of how much energy a home will use, given its design and equipment. Energy models are extensively researched and widely accepted, but they are also an estimate of how much energy a home will use. There is no way to account for certain variables, occupant behavior being a big one. However, models can be very useful tools for judging a home’s efficiency and for comparing the likely benefits of different efficiency strategies.

There are many ways to perform an energy model and models may vary in their intricacy, in part due to different software tools that can be used. Built Green’s modeling protocol is based on the software REM/Rate for single-family models and on eQuest for larger, multifamily models. 

Built Green’s… modeling protocol?

Yes, Built Green has a modeling protocol to ensure that projects are all being modeled the same way. On top of the different modeling tools, modeling is not an exact science and two different modelers could make two different decisions in how to account for certain components, with neither necessarily incorrect. To standardize our process and make sure that Built Green certification means the same thing for different projects, Built Green introduced modeling protocols to guide third-party verifiers and modeling experts. The protocols are designed with the input of experts and with the aim of making Built Green as accessible as possible for builders, while at the same time ensuring Built Green qualifies for various incentives. Third-party verifiers are a great resource for questions about modeling since they are the ones who often do the model or who work with the person doing the model.

So why a model?

Built Green is a certification that represents a building’s environmental gains above code. One of these gains is energy efficiency. Thus, projects need to demonstrate to Built Green that their energy consumption will be less than a similar code home and Built Green needs to demonstrate to governments and utilities that offer green building incentives that the program is meeting expectations. A model does just that.

What does the model show exactly?

Since Built Green is a regional certification, we look at improvement beyond the Washington State Energy Code. Models, therefore, show the percentage improvement of a Built Green home over its performance had it only been built to code. In other words, a model shows how much energy a home would use with code-compliant design and equipment and how much energy it would use as actually designed—the difference between the two being the energy reduction achieved by green upgrades and smart design. Built Green requires a 10% improvement over code for 3-Star certification, 20% for 4-Star, and 30% for 5-Star. Emerald Star homes must be net zero energy, which means these homes must consume the same or less energy than they produce via renewable energy in a year. These levels ensure Built Green certification carries meaning and acts a basis for incentives that benefit green builders.

Models are complicated; there is no doubt about that! Hopefully this post explains their purpose and how Built Green utilizes them. If you want to do a deep dive into the details of our modeling protocol, reach out to your third-party verifier for project specifics or to us for general information!

 

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