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Community and Q&A

Low-E Coating on Large-Format South-Facing Window

user-7568882 | Posted in Energy Efficiency and Durability on

Curious what the GBA hive mind thinks about this particular arrangement:

I am installing a custom picture window (large 6’x5′) on a south facing facade in central VT. The building is insulated but only R20, the building is single story 450 sq. ft., and the only source of heat is our wood-stove and possible passive solar. We have overhangs on this south facade which create some shade in the summer months but not much.

The Glass will be double pane ( would love to do triple but cannot justify the cost) and the question is: should I get Low E coating, and on what surface that coating should be on should I get it?


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  1. [email protected] | | #1

    Yes you should always get a LowE coating.
    If you want maximum solar gain then go with a single silver sputter coating on surface 3 of the IG unit, or opt for a hard coat.
    If you want moderate solar gain then go with a dual silver coating on surface 2.
    The more layers of silver the better the U factor of the unit, but the lower the SHGC

  2. Expert Member
    Akos | | #2

    For my own windows, I went down the rabbit hole of energy modeling and picking coatings based on that. Technically this is 2% more efficient but fails to take into considerations comfort. When it gets cold out on clear nights, I can feel the cold air cascading off the windows, I regret not going to triple pane with soft coat low E.

    Get quality windows, get the lowest U value your budget allows, don't worry about SHGC.

    P.S. Around me, for a single fixed window, the cost of triple pane is not all that much more, it is well worth it just for improved comfort.

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