Did you ever wonder what the surface temperature is of your solar kitty?
As you can see, Natasha runs about 112F on a clear, cold winter day in Denver. Note: she is laying in front of a window with an SHGC (solar heat gain coefficient)of 0.56. That's far higher than the average low E window which has an SHGC of about .32. What's that mean to a cat? About 15F. A black surface in front of a conventional low E window under the same conditions is around 97F. Still warm, but that's a significant penalty for not specifying the right windows.
Hurd "hard coat low E" windows from Rocky Mountain Solar Glass has been the only local solution I have found for passive solar. Serious Windows (formerly Alpen) should also be able to supply a high SHGC low E window. Most other window suppliers and manufacturers have no clue about this issue.
Increased solar gain in the summer isn't a concern, because these are south facing windows. In the summer, the sun is high in the sky, and the window is completely shaded by the properly designed overhangs. Even the Energy Star program is silent on this, although their energy modeling computer programs do give credit for high SHGC windows on the south side.
Increased solar gain in the summer isn't a concern, because these are south facing windows. In the summer, the sun is high in the sky, and the window is completely shaded by the properly designed overhangs. Even the Energy Star program is silent on this, although their energy modeling computer programs do give credit for high SHGC windows on the south side.
