Energy Guide

How It Works
A Whole House Fan can help reduce the mean radiant
temperature of the surfaces inside your home by flushing
the heat out of your living and attic space and replacing it
with cool outside air. By cooling surface temperatures for
added comfort, the Whole House Fan differs from a
conventional central air conditioner that recycles indoor
air and generally does not provide attic cooling.
Before the temperature rises during the day, or as stated in
the manufacturers recommendations, close and shade all
the windows and doors to trap the cool air in your home.
This will delay the operation of your cooling system. When
the temperature outside drops below the interior temperature
of your home, open your windows and operate your Whole
House Fan. Operating your fan in this way may shorten the
number of days you will need to use your central air condi-
tioner, saving energy and money.
For peak fan operation, an adequate
amount of cool fresh air must be supplied
through open screened windows and
doors. Use this table as a guideline to help
you determine how many windows and
doors to open.
If your Whole House Fan has a 3,000
cubic feet per minute (cfm) capacity, you
will need a minimum of 12 square feet of
fresh air opening. In this case, you will
need to open the following minimum
amount of screened windows:
One window measuring 2 ft x 4 ft = 8 sq ft
One window measuring 2 ft x 2 ft = 4 sq ft
Opening both windows 12 sq ft
Features
Most fans are available with the following options:
•
Wall-mounted controls
•
Two speed/variable speeds
•
Belt or direct drive
•
Horizontal or vertical mount
•
Insulated louver covers (during winter when fan is
not in use)
Consider a fan with at least a high and a low speed. The
high speed can be used for flushing the initial heat build-up
from the home, and the low speed may be used for gentle
air circulation and continued cooling.
A belt-driven fan is generally quieter than a higher R.P.M.
direct-drive unit, but will require periodic maintenance of the
belt and pulley assembly.
Selection and Sizing
Proper sizing will allow you to select the smallest fan to
adequately cool your home. Check the manufacturer’s
specifications or use the following table as a guide:
To calculate the fan capacity for any
sized area, use the following formula:
Floor Area (sq ft) x 3 = Cubic Feet
per Minute (cfm) Fan Capacity
For ceiling heights other than eight
feet, use this formula:
House Volume x 0.375 = Cubic
Feet per Minute (cfm) Fan Capacity
Note: When the floor area of your
home is between fan sizes, select
the next larger fan capacity.
TECHNICAL SHEET
Whole House Fans
Use Up to 90% Less Energy than a Compressor-Based Air Conditioner
In the summertime, the air inside your home is heated during the hot part of
the day. In the morning or late evening, the outside air is frequently cooler than
the inside of your home. This is the best time to open screened windows and
doors and operate your Whole House Fan.
Whole House Minimum Fresh
Fan Capacity Air Openings
1,000 cfm 4 sq ft
1,600 cfm 7 sq ft
3,000 cfm 12 sq ft
3,600 cfm 15 sq ft
4,200 cfm 17 sq ft
4,800 cfm 19 sq ft
5,400 cfm 22 sq ft
6,000 cfm 24 sq ft
6,600 cfm 27 sq ft
7,200 cfm 29 sq ft
Example
House Size Fan Capacity
Floor Area 8 ft Cielings
(square feet) (minimum cfm)
1,000 sq ft 3,000 cfm
1,200 sq ft 3,600 cfm
1,400 sq ft 4,200 cfm
1,600 sq ft 4,800 cfm
1,800 sq ft 5,400 cfm
2,000 sq ft 6,000 cfm
2,200 sq ft 6,600 cfm
2,400 sq ft 7,200 cfm