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Community and Q&A

UA and Rescheck

Aj Builder, Upstate NY Zone 6a | 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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  1. GBA Editor
    Martin Holladay | | #1

    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.

  2. Aj Builder, Upstate NY Zone 6a | | #2

    Great. Thanks Martin

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