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window specs for southern 4a climate zone?

BrunoF | Posted in General Questions on

I’m planning to build my house in zone 4a, right on the boarder of zone 3a.  The front of the house faces NNE, and the house will be in a somewhat wooded area but I do plan to clear out the south part a bit.  My high-level plan was to put as many layers of LowE coated glass as I can get on the south facing windows that will get direct sunlight and just one layer of LowE on the north facing windows.  This is not a passive house and the overhangs are only 16″ so the only windows protected from the sun will be those under the front and rear porches.

All the window, glass, spacer, etc. options available online have only led to confusion.  Would it be as simple as my idea listed above for my climate or do I need to consider more details in order to properly spec out the window glass?


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  1. walta100 | | #1

    I think the smart move is to build a computer model of your house enter your cost per square foot for all your window options and pick the window with the lowest cost of ownership.

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    Note if you have more than one type of window in your home the amount of visible light transmitted thru the different windows can look odd.

    When I modeled my zone 4 home, I found the U factor made a difference within limits making argon dual pane windows my best option. Triple panes did lose less heat but not enough to recover their higher cost. The coating did not move the needle in my model.

    Consider smaller windows cost less and lose less heat.


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