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Passive Solar and Energy Efficient Home
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, what we end up with is a building which may benefit from solar, although 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, from the experience of our ancestors who lived in caves, and from recent computer generated studies.
The solar guidelines in this article are just that, guidelines. However, we hope that they help you as you start planning for your solar home.
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.
A compass will point to magnetic North/South, but a solar home or collector works best when it faces TRUE SOUTH.
Why not a compass?
If not with compass, then how?
When is Solar Noon?
1) Time zones artificially place large geographic areas on the same clock time (hint: when solar noon occurs in Calais, Maine, the sun still must travel several hundred miles before reaching solar noon over Buffalo, New York - yet these two cities are in the same time zone.) Basically, every degree of Longitude away from the Standard Time Meridian for your time zone counts for 4 minutes of clock time.
2) Equation of Time: as it turns out, days on planet earth are not of constant length. As the earth orbits the sun, our speed of rotation on our own axis actually varies slightly each day. This means that we must take this variation into account when calculating solar noon: in February the sun is more than 14 minutes behind schedule while in October it is more than 16 minutes ahead. You can see a graph of the equation of time at: http://www.srrb.noaa.gov/highlights/sunrise/eqntime2.gif
3) Daylight Saving Time - don't forget to adjust the calculation for the appropriate method of time keeping. Daylight Saving Time starts the first Sunday of April and ends the last Sunday of October.
Sound a litle complicated?
Solar Access: Buildings or trees too close to your home could block the low winter sun. Make sure that if you plant trees close to your home, that they lose their leaves in the winter-if you live in a climate where the trees lose their leaves.
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 standard floor coverings such as carpet, vinyl tile, or wood. 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.
Example: A 3'0"X5'0"window is 15 sq. ft.
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.
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.
Contact your local county agent or state energy office for recommendations specific to your area. And again, it's your solar home, so you can design it how you want to. However, these simple recommendations are a good place to start.
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