Shading a West Wall When You Add Windows

On a west wall in Austin, TX, the sun arrives low and hard from about three in the afternoon until it sets, and a new window facing that way takes the full load, so in work planned through austin new windows le mistral houston the size of the glass is settled last. A west window adds daylight to the room, but it also adds heat at the hottest part of the day, so the decision about size and shading comes before the decision about the frame.

Why the west wall is the problem wall

The afternoon sun strikes the glass nearly straight on, and an overhang of normal depth does little against a sun that low. The heat arrives as solar heat gain through the glass and as warmth soaked up by the wall itself. A west facing room can run several degrees hotter than the rest of the house well into the evening.

Fewer and smaller on the west

The simplest fix is to put less glass there. One modest casement or a pair of small units lights the room without turning it into an oven. Use a transom on the west wall for daylight and put the larger picture window on the north or east, where the light is steady and the heat is gentler. A clerestory on the west gets some light with a small area.

Glass that fights the sun

A low e coating reflects part of the sun heat, and the shgc number tells how much gets through. For a west wall, a low shgc is worth more than a low u factor. Double pane insulated glass with argon fill and a warm edge spacer is the standard, and triple pane adds more at higher weight. A bronze or gray tint cuts glare but darkens the room.

Shading outside the glass

Shading works best outside the window, before the heat gets in. A deep porch roof, a pergola, an awning, a vertical louver or a shade tree on the west side will all help. An exterior shade screen drops the heat further than an interior blind. Interior shades stop the glare but the heat is already inside the house.

Frames on a hot wall

A dark vinyl window on a west wall gets hot enough to warp if the color is wrong, so a light color or a fiberglass window or an aluminum window with a thermal break holds up better. A wood window with a clad exterior suits older houses. Seal failure shows up first on the hottest wall, as fog between the panes.