Residential ENERGY Ratings
When I see builder specs provided to us, for homes needing to comply with 2021, I sometimes find myself looking at the R402.4.1.2 section in the IECC.
I have come to be familiar with measuring any units air leakage by ACH. That is what is used, and is very efficient.
Remembering the allowed .28 CFM50 / ft^2 shell area (.30 for individual dwelling units) has shown me homes passing code under prescriptive path multiple times with an allowed 6 , 8 , even 9 ACH. For context I do work in Climate Zone 5 shooting for mostly 3 ACH. The flexibility allowed that I have noticed brought me to making this LinkedIn post.
Do people ever choose to go this route? Is it leverage or Band-Aid over injury? It brings up energy use questions, and equipment specifications needed for indoor air to be allowed in and out without having moisture problems or high energy bills. Also, with the rating software used here it will automatically calculate our shell area into the model but only once plan/design review is done. Using this test method (.28 CFM50 / ft^2 shell area) you would need to take all these things into consideration, maybe halting the whole process in its self.
Not all homes have decent sized HRV/ERV mechanical ventilation, I assume this would be easiest transition answer if we wanted to not worry about comfortability being compromised. Also a possibility of UA , HERS Index, and Carbon scores having a huge impact on already built models with too much volatility. You can pass air leakage testing but what are you going to install in the home?
As someone who works in office not doing actual inspections or testing, how do I know if it actually is a comfortable home testing with Cfm so high? I cannot fly out to every home I do ratings on.
We can pass at 9 ACH in Colorado, but is it actually going to provide the residents a home, or a slow built trap and waste of money?