UA and Rescheck
wjrobinson
| Posted in Energy Efficiency and Durability on
Just ran a Rescheck. I like the software, simple and seems to be informative possibly for more than just getting a passing Rescheck to submit.
Is there more I can learn from the reports listing of UA?
The software reports individual UA and total for the home.
Can one simply input these UA numbers into a formula to report BTU use per Delta T as Marc is doing in his great blog answering questions to do with mini split use?
Dana, Marc, Martin, others?
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Replies
AJ,
The heat loss formula for determining transmission losses through floors, roofs, and walls is
Q = A • U • ΔT.
In other words, the rate of heat flow through a building assembly (in Btu/h) is equal to the area of the assembly (in ft²) times the U-factor (in Btu/ft² • hr • F°) of the assembly times the ΔT (in F°).
This is explained in my blog, How to Perform a Heat-Loss Calculation — Part 2.
UA (defined as the "overall average heat transmission of a gross area of the exterior building envelope") is used to measure whole-building heat loss in Btu/h°F.
Area x U-factor = UA
Multiply the surface area of each exposed component of the building envelope by its U-factor to get its "UA" value. Add up all the UA values to get a total building UA value.
Great. Thanks Martin