Infrared Blocking for Windows
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I’m looking to find the highest VLT windows possible with UV and infrared blocking, for a pair of double pane, South facing windows. I know to look for low iron glass, with anti-reflection coating, which total, increases VLT by about 25% to 30% for a double pane. And I know that there are UV blocking coatings that can block 98% of UV while only lowering VLT by 2%. So far so good, we’re looking at around a 95% to 98% VLT.
What I can’t figure out is the infrared part of this. For this application, I’m only concerned with blocking the Sun’s heat/infrared from entering the room, not with retaining the inside infrared from escaping.
What do I look for? Is there a low-e glass type that lowers infrared entering, but has a minimal impact on VLT? I know there’s a LoE variant called i89 (which is for blocking indoor infrared from escaping out, so it doesn’t match my purpose), which has a VLT of 89%. Is an 89% VLT the best I could hope for with infrared blocking? And how much infrared would block?
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And where are the windows coming from? Who is the window manufacturer?
I'll likely need to have these glass panels custom made by a manufacturer of commercial display glass, but I'm looking to see if there are any residential, standardized specifications that might meet my needs.
I'm aware of the low-e specs. My understanding is that it aims at lowering not just infrared transmission, but also total solar energy absorption/re-radiation, as well as lowering infrared heat loss from the indoor space.
But I'm not concerned with the window's solar heat absorption and re-radiation. In fact, if I had to decide on a preference, being in a colder climate, I would prefer their absorption/radiation remains as high as possible, increasing solar heat gain.
I'm concerned with lowering infrared transmission specifically, to lower the sharp heat of full, midday, direct sun, while minimizing loss of VLT, that being the primary goal spec. A 13% total loss of VLT from filter treatments is the most I can accept for my purpose, less being preferable.