Whole House Attic Fans
The attic fan is a relatively
inexpensive and easy to
install option for cooling
your entire home.
The fan draws cool
outdoor air inside through
open windows and
exhausts hot room air
through the attic to the
outside.
The result is excellent
ventilation, lower indoor
temperatures, and
improved evaporative
cooling.
inexpensive and easy to
install option for cooling
your entire home.
The fan draws cool
outdoor air inside through
open windows and
exhausts hot room air
through the attic to the
outside.
The result is excellent
ventilation, lower indoor
temperatures, and
improved evaporative
cooling.
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What Are The Benefits?
A whole house fan can be used as the sole means of cooling or to reduce the need for
air conditioning.
Outside air temperature and humidity dictate times when the whole house fan would
be favorable over air conditioning. If both methods of cooling are present, a seasonal
use of the whole house fan (during spring and fall) may yield the optimum combination
of comfort and cost.
Economics of Operation
Operating a properly sized 2-ton, 10 SEER air conditioner in Atlanta, Georgia costs
over $250 per cooling season (1250 hours), based on 8.5¢/kwh, or roughly 20¢ per
hour of runtime. A large 18,000 Btu/hr window unit air conditioner with a 6 EER costs
more than 25¢ to operate for one hour.
By contrast, the whole house fan has a motor in the 1/4 to 1/2 hp range, uses
between 120 to 600 watts, and costs around 1¢-5¢ per hour of use.
What Are The Drawbacks?
A whole house fan has some drawbacks: the fan can only cool the inside of a house to
the outside temperature; unlike an air conditioner, it does not dehumidify; and dust
and pollen can be brought into the house.
Cooling Strategies
During the morning and late evening, the outside air is often cooler and can be used
to replace the inside air. It is important to partially open several windows to ensure
adequate airflow. Closing windows in unused rooms will create higher velocity air
movement in occupied rooms.
Running the whole house fan whenever outdoor temperatures are lower than indoor
will cool the house. Operate the whole house fan throughout the evening to cool
interior materials. An approximate rule of thumb would be to use the whole house fan
when outside temperatures are below 85°F.
As daytime temperatures rise, turn off the whole house attic fan. The cool room
materials (along with ceiling or circulating fans which create an additional cooling
effect) will help keep the interior more comfortable.
A whole house fan can be used as the sole means of cooling or to reduce the need for
air conditioning.
Outside air temperature and humidity dictate times when the whole house fan would
be favorable over air conditioning. If both methods of cooling are present, a seasonal
use of the whole house fan (during spring and fall) may yield the optimum combination
of comfort and cost.
Economics of Operation
Operating a properly sized 2-ton, 10 SEER air conditioner in Atlanta, Georgia costs
over $250 per cooling season (1250 hours), based on 8.5¢/kwh, or roughly 20¢ per
hour of runtime. A large 18,000 Btu/hr window unit air conditioner with a 6 EER costs
more than 25¢ to operate for one hour.
By contrast, the whole house fan has a motor in the 1/4 to 1/2 hp range, uses
between 120 to 600 watts, and costs around 1¢-5¢ per hour of use.
What Are The Drawbacks?
A whole house fan has some drawbacks: the fan can only cool the inside of a house to
the outside temperature; unlike an air conditioner, it does not dehumidify; and dust
and pollen can be brought into the house.
Cooling Strategies
During the morning and late evening, the outside air is often cooler and can be used
to replace the inside air. It is important to partially open several windows to ensure
adequate airflow. Closing windows in unused rooms will create higher velocity air
movement in occupied rooms.
Running the whole house fan whenever outdoor temperatures are lower than indoor
will cool the house. Operate the whole house fan throughout the evening to cool
interior materials. An approximate rule of thumb would be to use the whole house fan
when outside temperatures are below 85°F.
As daytime temperatures rise, turn off the whole house attic fan. The cool room
materials (along with ceiling or circulating fans which create an additional cooling
effect) will help keep the interior more comfortable.
Alternative-Heating-Info.com
