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I am interested in the Condensation Resistance values that I see on different windows

msloot | Posted in Energy Efficiency and Durability on

I see that the NFRC has these calculated for all different windows.

Does anyone know how to correlate the CR value with actual temperature and humidity levels in the house. Any calculator out there somewhere?

i.e. what CR value is needed to prevent most condensation on a window when the outside temperature is -10 degrees and the inside temperature is 70 degrees and the indoor RH is 25%?

Thanks
Marc

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Marc,
    There is no simple answer to your question. To learn more about the Condensation Resistance (CR) rating scale, I suggest that you read the following article: Rating Windows for Condensation Resistance.

    Different parts of the window have different temperatures, and wind speed and window exposure can affect condensation (as can the presence of curtains or blinds).

    If you know the temperature of a certain area of the interior of your window, and you know the indoor relative humidity, you can use the psychrometric chart to determine whether that area of the window is above or below the dew point. For more information on the psychrometric chart, see Are Dew-Point Calculations Really Necessary?

  2. msloot | | #2

    Thanks Martin.
    The articles you referenced are very helpful.
    I was hoping there was a calculator for CR value similar to the one that AAMA has for CRF values.
    http://www.aamanet.org/crfcalculator.asp?sect=1&id=334

    Looks like that is not the case, and while the AAMA CRF calculator seems nice to determine a reasonable CRF to use , I cannot find CRF values for any windows.
    -Marc

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