Passive Solar and Energy Efficient Home Design
EVERY HOME IS A SOLAR HOME
It is a fact, that everything we build is solar. When we ignore solar energy during the design stages we end up with a building which may benefit from solar, though it is just as likely to be beat up by solar energy.
A passive solar design will not only lower your utility bills, it will be comfortable. Comfort is priceless.
The following guidelines are drawn from research and practical application,from successes and failures, and from our ancestors who lived in caves to computer generated engineering studies.
Orientation: The longest wall of the home should face south. The winter sun rises South of East and sets South of West. Placing more glass on the South wall will ensure that your home receives free solar energy.
This same orientation helps to prevent the high summer sun from entering the home.
A compass will point to magnetic North/South, but a solar home or collector works best when it faces TRUE SOUTH.
In the El Paso area true south is 12 degrees East of magnetic South. This declination from magnetic south varies across the country depending on longitude.
Solar Access: Buildings or trees too close to your home could block the low winter sun.
Windows: The amount of glass on the South wall may equal 7% of the homes total square footage. (Example: 2,000 Sq. Ft. = 140 Sq. Ft. of glass.)
To avoid overheating, this amount of glass should not be exceeded. The 7% applies to conventional home construction with wallto wall carpeting. Increasing glass area above 7% will require additional thermal mass i.e. concrete/tile floors, rock, brick, concrete or adobe walls.
The 7% amount is NET sq. ft. or the total window area less the trim etc.
Multiply the entire window by .8 to get the net glass area.
Example: A 3'X5' window is 15 sq. ft. 15 X .8 = 12 sq. ft. net
East and North glass should be limited to no more than 4% of total sq. ft. (Maximum)
West glass should not exceed 2% of total sq.ft.(MAXIMUM)
Landscaping: Plant deciduous or evergreen trees on the east, west and north sides of the home. Xeriscape!
Avoid dark colors, inside and out.
Insulate exterior of slab/foundation with extruded polystyrene sheets. R-5 for moderate climates, R-10 for colder climates.
Sole Plate: Install insulation between bottom plate and concrete slab or foundation.
Walls: In 2X4 frame walls use min. R-13 batts and sheath exterior with minimum R-4 ridged insulation boards (expanded polystyrene). Cold climates might use 2X6 frame walls with R-19 batts.
Sprayed cellulose in wall cavities is more effective than batts.
Attic: R-30 blown in insulation for moderate climates. Colder climates range from R-40 to R-50.
IMPORTANT: Prior to installing wall insulation, use cans of expanding foam insulation and/or caulk to seal all electrical and plumbing penetrations, around doors and windows.
Tape/seal all joints in ductwork. Duct work should be installed in interior (heated) space so that heat or cold is not lost to unheated spaces (attic).
Furrdowns should be sheathed and sealed prior to installing duct.
Insulate walls surrounding furnace closets and seal return air plenum.
Doors: Use metal, insulated exterior doors. R-5.9
Ventilation: Place and size windows to take advantage of natural ventilation and prevailing breezes.
Fans: The use of ceiling fans can drastically reduce the running time of air conditioners.
Contact your local county agent or state energy office for recommendations specific to your area.
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