CSI NUMBER(S):
- Ceiling Fans
- 157-290-2500 to 157-290-3300
- Whole House Fans
- 157-200-3500 to 157-200-3600
DEFINITION
The traditional method for creating comfort in hot/humid climates is through air movement. The modern home can use this traditional method readily with ceiling fans. to move air in individual rooms, and whole house fans to pull in cooler outside air.CONSIDERATIONS:
Moving air with ceiling fans allows building occupants to feel comfortable at higher temperatures. As a result, mechanical cooling equipment temperature settings can be higher and an energy savings greater than the energy consumption of the fans can be realized. According to the Texas Energy Extension Service, for a 3 ton cooling system costing $550 per season, raising the thermostat from 75 degrees to 80 degrees can reduce the operating cost $151. Operating a ceiling fan 10 hours a day or more can cost less than $3 per month. In the heating season, ceiling fans can help bring the warmer air that stratifies near the ceiling down to where the occupants are located. A low speed that does not create significant breeze is best for this heating season application. The most useful ceiling fans will have variable speed settings. A whole house fan offers energy savings and comfort when operated in conjunction with or without mechanical cooling. The performance of a whole house fan in hot/humid climates is optimized when used in homes with high mass interiors and reduced moisture adsorbing materials (i.e. carpeting).| Commercial Status | Implementation Issues | ||||||
|---|---|---|---|---|---|---|---|
| T E C H N O L O G Y | S U P P L I E R S | C O S T | F I N A N C I N G | A C C E P T A N C E | R E G U L A T O R Y | ||
| Ceiling Fans |  | | | | | | |
| Whole House Fans | | | | | | | |
| Satisfactory |
 | Satisfactory in most conditions |
 | Satisfactory in Limited Conditions |
 | Unsatisfactory or Difficult |
COMMERCIAL STATUS
TECHNOLOGY:
Well-developed.SUPPLIERS:
Abundant Ceiling fans: $35 – $200; whole house fans with louvers and timers: $300 and up depending on the size.IMPLEMENTATION ISSUES
FINANCING:
N/APUBLIC ACCEPTANCE:
Ceiling fans are viewed positively by most people for their aesthetic appeal as much as for their comfort enhancing capabilities. Whole house fans can be loud to some people and require the opening of windows during the night, raising security concern. The doors to rooms in the house should also be open to permit air movement. Grills/louvers, adequate opening at the door bottom, or transoms can also accomplish this.REGULATORY:
Standard electrical code.GUIDELINES
1.0 Ceiling Fans
Ceiling fans should be operated only when the rooms are occupied. A motion sensor or a clear policy of operating ceiling fans only when using the room is needed. Variable speed fans are preferable so that the lowest speed can be used in the heating season to accomplish destratification without causing excessive draft.1.1 Energy use of ceiling fans
Ceiling fans use about the same amount of energy as a 100 watt light bulb.Ceiling fans permit raising the thermostat setting on an air conditioning system 4 to 6 degrees.1.2 Selecting a ceiling fan
A good warranty indicates better durability. Fans with metal motor housings may require annual oiling while plastic motor housings will not, but may have better warrantees and be worth the added maintenance. Blade material will not affect performance. Use ceiling fans in heavily used rooms. Match the fan size to the room size.2.0 Whole House Fan
Whole house fans are useful when outdoor temperatures are within the comfort range. The key consideration in our region is the typically high humidity which can postpone nighttime cooling. The high outdoor humidity will also increase the humidity in the home when brought in by the whole house fan. This humidity will reduce the cooling effectiveness of daytime mechanical cooling due to what is termed the latent cooling load. This effectively causes the mechanical cooling to operate more, reducing the net energy savings from using a whole house fan.2.1 Optimum benefits from whole house fans:
A high mass interior and minimal moisture-adsorbing materials (fabric furnishings, draperies, and carpets) increase benefits. (A high mass interior will stabilize temperature swings in any home; see section on Passive Solar Design) In the heating season, it is important to insulate the whole house fan opening to prevent heat loss. Minimizing the carpeting in a home is an excellent strategy in reducing the latent cooling load. (Energy savings from a whole house fan can still occur in light frame, conventionally furnished homes.) Windows should be opened in all the rooms that are to be cooled and the air path to the whole house fan not obstructed by tightly closed doors or other means. Windows may be opened by controlled mechanical means in conjunction with the fan turning on at certain outdoor temperatures; this can reduce manual operation. In either case, a security concern may necessitate the use of barred window guards. These extra expenses can significantly delay a payback on energy savings.2.2 When to use a whole house fan
When the outdoor temperatures are below 82 degrees and the relative humidity is less than 75 percent, a whole house fan can cool a house by itself.2.3 Selecting a whole house fan:
The fan should be sized to accomplish a minimum of one-half air change per minute. Use a fan with variable air flow. Larger fans are generally quieter than smaller fans, particularly at lower speeds. Employ a fire safety feature that will deactivate the fan during a fire.