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  1. LucyF | | #1

    Roger, I couldn't get that link to work, but I did find the original paper at the Oak Ridge website [DOC]
    A Prototype Roof Deck Designed to Self-Regulate Deck Temperature and Reduce Heat Transfer.

    The best drawing of the design is included in the press release about it.

    This is particularly interesting to me because of retrofits I want to do on a couple of houses.

    Thank you so much for posting that.

  2. Lizzieplants | | #2

    Is this a design that would be worth considering for a new near passive house or is it more beneficial for retrofits?

  3. GBA Editor
    Martin Holladay | | #3

    The payback period for these details is very long, as ORNL researchers admit. It only makes sense in hot climates with high air conditioning bills -- and probably only for homes with attic ductwork (something you will never find in a Passivhaus).

    My advice remains unchanged: if you pay attention to air sealing the attic floor, and if you keep all ductwork and HVAC equipment within the home's conditioned space, and if you have at least code-mandated levels of insulation on your attic floor -- then it hardly matters what your attic temperature is.

  4. eyremountllc | | #4


    I agree. This is particularly exciting for retrofit projects.

    Elizabeth and Martin,

    I agree. Definitely retrofit. No one with the right mind should be putting HVAC ducts in the attic in a new construction, also, why would anyone not seal the attic floor! The study concludes, "The most cost-effective retrofits for an attic are repairing the leaks through the attic floor and in the HVAC ducts".

    I find it interesting that "In Baltimore the payback is estimated at 11 years for the insulated and ventilated roof deck as compared to a 68 year payback for sealing the attic with open cell spray foam."

    I wonder though if the outcome would be different if instead of using open cell spray foam to seal and insulate, tape the attic with an air-sealing tape from either the ProClima or the Siga family and then use batt/cellulose to insulate.

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