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On a hot day, temperatures in an attic can reach 150o
Fahrenheit or more. Much like a radiator transfers heat in the winter time to
warm a room, a hot attic will transfer unwanted heat to the living spaces
below, making you uncomfortable, pushing up your electric bills and wearing
out your air conditioner.
Most homes have "passive ventilation" in attic -- vents that allow some of
the hot air to escape. These may be openings under the eaves, at a roof gable
or along the ridge.
Attic fans force hot air out of the attic space and replace it with cooler
air entering through these vents. Electrical fans -- one or more, depending on
the size of the attic -- can be positioned at the highest points of the roof,
where the hot air rises. These require an electrical circuit and can be
controlled three ways: by a switch, which means the fan runs only when you
turn it on; a timer, so it operates at appointed times each day; or by a
thermostat. which operates the fan whenever heat builds up and it is needed.
Simpler devices are wind-driven turbines (small rotating devices), which
also can pull hot air from the attic and send it outside.
Insulating the attic is also important -- most climates in California
require a minimum of R-38 insulation in the attic. ("R" means
R-value.) Older homes often contain much less than this amount. Old
insulation may also have compacted over the years, becoming less efficient. It
should be removed and replaced.
(-- from California Life, The Sacramento Bee,
8/10/96)
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