CBECC 2022 Existing Alterations Giving Results of All 0s

asked 2024-08-20 15:25:51 -0600

ms0130
11 ●3

updated 2024-08-21 06:18:14 -0600

Aaron Boranian

14250 ●86 ●24 http://bigladdersoftware.com/

I am running a school model in CBECC 2022 - it is an existing school with window retrofits so I selected Existing - Alterations. The software was able to complete the analysis but the results of energy use is all 0 - even interior lighting I assigned has no energy consumption results.

I realized when I selected Existing - Alterations in the Project interface, only DHW does not gray out. Can that be the potential issue?

When I run the idf in E+, I was able to get consumption results.

answered 2024-08-29 11:49:17 -0600

Greg Collins

550 ●8 http://www.zeroenvy.com/

It's very hard to troubleshoot based on such limited information. That said, make sure that the "status" of your envelope (especially fenestration) is what you want.. "Existing" for all envelope except those new windows which will be "altered" or "new" depending on the code definitions. It gets tricky if your replacement windows are larger than the existing openings because some portion of the window is "altered" and the rest is "new". CBECC software isn't great in these situations, and prescriptive makes a lot more sense. Note also that if you're using the performance approach because you can't comply prescriptively based on new window size and/or performance values, that's not going to change by simply modeling it. You'll need to expand the scope of the compliance model so that your envelope penalty is offset by lighting or something else that shows savings.