Solar builders have a wide array of “aperture” (window) options, and with sufficient demand, perhaps manufacturers will begin to offer the kind of highly insulating windows that also have high solar heat gain coefficients (SHGC, as listed on the National Fenestration Rating Council label on new units). Only some Canadian manufacturers and a few high-end custom window makers in the United States are selling windows that are appropriate for passive solar applications. (Unfortunately, the current federal tax credit program, in which consumers can subtract up to $1,500 from their federal tax liability for installing high-efficiency windows, excludes high solar heat gain windows from eligibility, since it calls for an SHGC of ≤ 0.30.)
Good building designers are beginning to understand the importance of overhangs, both for rain protection and for preventing summertime overheating in passive solar homes.
Many also appreciate the value of a south-side open floor plan, with private rooms, entries, and utility/storage spaces clustered along the north. An elongated east-west axis enhances a southern exposure that’s oriented within 15° of true south to optimize solar availability.
