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Community and Q&A

Installing a window

uKUohMVY9p | Posted in Green Building Techniques on

This is my problem:
I am designing a passive house and as far as we all know, the highest heat loss is through windows. The wall is made of 250mm brick inner leaf, 180mm insulation and outside rendering. Does anyone has any ideas about how to install a plastic frame window in the most energy efficient way in this type of wall?
Giving visual examples would be perfect.
Thanks a lot!

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  1. GBA Editor
    Martin Holladay | | #1

    I'm not sure that I agree that the "highest heat loss is through windows" -- for one thing, air leakage in a leaky house can account for a tremendous amount of energy waste, and for another thing, properly specified windows can gather more heat than they lose. In a passive house, especially, windows provide heat gain, not heat loss.

    180 mm of insulation is 7 inches. That's something, but it's not a huge amount, especially if you are using EPS or Roxul. Depending on what type of insulation you are using, that's between R-24 and R-47.

    Good window installation depends on carefully considering thermal bridging. The best Passivhaus builders use fixed glazing whenever possible (rather than operable units) and often use a technique called "overinsulating the exterior frame." If the technique is new to you, you should visit the Passivhaus Institut Web site and begin studying some of their window details.

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