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Let me put my headline question another way: Is prediction of building performance the highest use of energy modeling during building design?
This question came to mind after I sent an email to our members this morning about our upcoming (July 9th) webcast on Energy Modeling for Early Design Decisions. One individual responded to me and questioned the credentials of the panel of experts we assembled for this roundtable discussion.
He wrote: “Until you have an energy model that is a good prediction of the way a building operates and the amount of energy used (and is verified by a independent 3rd party) then one needs to be wary” about claims of expertise in modeling.
There is a lot of value in an energy model that reflects the building “as built”: validating LEED points, validating code compliance, and setting the stage for measurement and verification.
But, as I wrote recently in the EBN article, Energy Modeling: Early and Often, “after the massing, orientation, envelope and glazing design, and mechanical systems in a building are already specified, and hundreds of hours of work have already been put into those designs—the modeling might have little value beyond keeping score.” With a quote from Marcus Sheffer, who will be on our webcast panel (and who wrote the book on energy modeling in an integrative design process), I went on to say:
“It blows me away that that’s where we are,” says Marcus Sheffer, an energy consultant with 7group. As critics have pointed out, a 'green' building modeled to save a certain amount of energy doesn’t necessarily end up doing that. Given accurate inputs, models are accurate at forecasting energy use, says Sheffer, but “models can’t accurately predict the future”: actual operating conditions will always differ from modeled conditions. This typically happens because equipment and controls are installed differently than modeled, or because weather patterns or occupancy are different than expected. The real value of modeling is not predicting energy use but making relative comparisons among design options, says Sheffer.
I agree with Sheffer. There is way too much focus put into the energy model and how predictive it is of performance, and not enough put on iterative modeling during early design to choose between designs A, B, C, D, and so on.
Our most stringent energy codes and prescriptive guidelines today get us no more than 40% savings over common practice. What we need are 50%, 60%, and greater savings, and we need early modeling to get there.
Do you agree? Disagree? Why? I hope you’ll join me and Marcus Sheffer, Troy Hoggard, Amanda Bogner, and Prasad Vaidya for a lively discucssion at our July 9th, 1:30 p.m. ET webcast on Energy Modeling for Early Design Decisions. It’s free to sign up.
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