I carefully researched my window glass options before soliciting estimates for my Seattle-area home. As I was warned, most professional window people are clueless about low- vs high-SHGC coatings. Pretty surprising, as Seattle may be the most logical place in the entire country for high-SHGC glass. (Not only are we a heating-dominated climate; we don't need air conditioning at all.)
The sales people were very open to my request (LoE-180 on the south windows, LoE-272 on the north)--changing from disagreeing with me, to agreeing with me, once I explained the reasoning. But now I (and they) are getting the runaround from potential window suppliers--Comfort Design and Simonton. Assertions made thus far:
1) "LoE-180 is the same thing as i80", which I find suspicious, as this sounds a lot like *i81* which is a different kind of coating altogether (pyro coating on surface 4, the indoors-facing "outside" of the IGU).
2) "LoE-180 / i80 is a new product" and they aren't comfortable warrantying it. Pretty sure this is bs.
3) I can only get this if I spring for tempered glass.
This is rather discouraging. The federal tax credits may have expired, but it seems that Physics has not yet prevailed in the industry. What's a homeowner to do?