Glass for the Phoenix Sun
Which ProVia Glass Fits a Phoenix Home
ENERGY STAR rates windows by climate zone, and Phoenix and the Valley cities we serve are in its Southern zone. A window there needs a U-factor of 0.32 or lower and a solar heat gain coefficient (SHGC) of 0.23 or lower. U-factor is how much heat passes through the whole window; SHGC is how much of the sun's heat comes in through the glass. Lower is better for both.
ProVia names its glass packages with letters: D for double pane, T for triple, L for low-E, A for argon gas, K for krypton gas, UV for an extra ultraviolet coating and HC for a hard coat on the second pane. Here is what ProVia's Energy Performance Calculator shows for a double hung window in each package, across its lines:
| Package | What it is | U-factor | SHGC | Southern zone |
|---|
| DLA | Double pane, low-E, argon | 0.27 to 0.29 | 0.27 to 0.29 | Does not qualify |
|---|
| DLA-UV | Double pane, low-E with UV coating, argon | 0.27 to 0.28 | 0.20 to 0.21 | Qualifies |
|---|
| DLA-UV-HC | DLA-UV plus a hard coat on the second pane | 0.23 to 0.24 | 0.19 to 0.20 | Qualifies |
|---|
| TLA-UV | Triple pane, low-E, UV coating, argon | 0.21 | 0.18 | Qualifies (not on ecoLite) |
|---|
| TLK-UV | Triple pane, low-E, UV coating, krypton | 0.17 | 0.18 | Qualifies (not on ecoLite) |
|---|
So on a Phoenix house the starting point is DLA-UV, which is standard on Endure and Aeris. Picture, slider and casement windows have numbers of their own. One exception the calculator shows: an Aeris picture window with DLA-UV comes in at 0.24 SHGC and isn't certified, while the same window with DLA-UV-HC is.
ProVia's low-E coatings also reflect ultraviolet light, which helps keep floors and furniture from fading; its brochures say coatings like these cut fading by as much as 75% without noticeably cutting visible light. The trade-offs ProVia points out: the extra UV coatings block light houseplants need, and the TLA triple pane packages may look slightly green. ProVia also makes tinted glass in bronze, gray, blue and green. It says bronze, gray and blue cut solar heat gain, and bronze and gray cut glare.
Thinking of adding window film later? ProVia's warranty doesn't cover tints or films added after the window is made, or damage they cause. Getting the right glass from the factory keeps the warranty whole.