Requirements |
1 |
Building layout must maximize passive solar gain (less used areas on north side, etc.) |
2 |
At least half of the window area must be facing within 30 degrees of due south |
3 |
South window area greater than 7 to 9 percent of total floor area |
4 |
Average window U-factor not greater than 0.35 (area weighted) |
5 |
South window Solar Heat Gain Coefficient (SHGC) at least 0.55 |
6 |
Thermal storage (expressed in diurnal heat capacity) is equal to 30 times the area of south facing windows |
7 |
Adequate overhangs |
8 |
Less than 5 percent south shading from trees or buildings |
9 |
North windows less than 2 percent of floor area |
10 |
Skylights must be tinted and have an SHGC of no more than 0.30 |
11 |
Skylights no more than 1 percent of roof area |
12 |
West window SHGC less than 0.40 |
13 |
The house has an operable window or skylight near the highest point in the roof or a whole house fan |
Strongly Recommended |
1 |
Home is performance tested by certified third party |
2 |
Use thermal mass not thicker than 6 inches in southwestern and eastern Oregon and not thicker than 4 inches in northwestern Oregon |
3 |
Non-occupied spaces (garage, utility room, etc.) located on north and west sides of home |
4 |
High-efficiency furnace (90 percent+ efficiency) |
5 |
Airlock main-entry doors |
6 |
Use deciduous trees on west and east side of home to reduce summer cooling load |
7 |
Keep use of skylights or “light-tubes” to a minimum |
8 |
Install heat a recovery ventilation system |
9 |
Use a moderately dark thermal storage color (brown, red, dark gray, green, dark tan . . .) |