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