“UA,” infiltration, and REScheck?
nnovel01
| Posted in Energy Efficiency and Durability on
Hello,
Does anyone know if REScheck accounts for infil/exfiltration in some way, in the reported UA value? I suppose this might be the same as asking, does the code account for infiltration? I recognize that since there is no input for infiltration in REScheck, the answer might be a simple no.
The reasoning behind the question is, we are trying to get a handle on how windows with different infiltration ratings might affect overall energy use and comfort: Given a particular design and site, would low-infiltration windows be smart?
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Replies
Nick,
Here's the answer to your question (from a document called "REScheck Basics Transcript"):
"The software [REScheck] already assumes air infiltration. It has an air infiltration value within the software; and so if you have components that have some air barrier features that are good that make that component that much better than your typical other insulation products, so to speak, you can't show that in REScheck. REScheck is a very simplistic tool that is just U-factor times area, the assembly with the insulation, the assembly with the U-factor and the solar heat gain of your windows. Anything above and beyond this type of showing compliance, which is a trade-off for the U-factor times the area, you'd have to use a performance-based tool to do that, and then you can start defining out the more additional features of your project with a performance-based tool. REScheck is not a full performance-based tool that does not show energy usage and energy savings."
Martin,
Thanks! I'm Nick. Sorry, I just set up my profile here at GBA, and haven't adjusted all the fields.
I had seen some of your answers as I was looking for similar questions. Glad to have gotten your attention. Thanks for the answer, and the link to the doc - very useful.
Even if infiltration is not controllable, It's good to know that there is some baseline infiltration accounted for, so that the UA better correlates to heat transfer in realistic conditions (or some average thereof).
The answer to your last question, " Given a particular design and site, would low-infiltration windows be smart?" is yes. Even if that doesn't show up in REScheck, there is a comfort benefit and a energy savings benefit.