|
Heating & Cooling
How can a whole house fan save you money and cool your home?
 Keeping cool indoors when it is hot outdoors is a problem. The sun beating down on our homes causes indoor temperatures to rise to uncomfortable levels. Air conditioning provides some relief. But the initial costs of installing an air conditioner and the electricity costs to run it can be high. In addition, conventional air conditioners use refrigerants made of chlorine compounds, suspected contributors to the depletion of the ozone layer and global warming. But there are alternatives to air conditioning. |
General Guidelines
Keep heat-producing appliances away from your thermostat.
If you have central air conditioning, set your thermostat to 78°F or more during the cooling season, 85°F or more when you leave your home for more than four hours. Unless you have furniture, art or equipment that could be damaged by excessive heat, turn your cooling unit off when you leave your home for more than 24 hours.
During the heating season, set your thermostat to 68°F or less during the day, 60°F or less at night or when you leave your home for more than four hours.
Go to Insulation and Windows for information on protecting your home's
climate from outside heat or chill.
Staying Cool
- An alternative way to maintain a cool house or reduce air-conditioning use is natural (or passive) cooling. Passive cooling uses nonmechanical methods to maintain a comfortable indoor temperature.
- The most effective method to cool your home is to keep the heat from building up in the first place. The primary source of heat buildup (i.e., heat gain) is sunlight absorbed by your house through the roof, walls, and windows. Secondary sources are heat-generating appliances in the home and air leakage.
- Specific methods to prevent heat gain include reflecting heat (i.e., sunlight) away from your house, blocking the heat, removing built-up heat, and reducing or eliminating heat-generating sources in your home.
|
Removing Built-Up Heat
Nothing feels better on a hot day than a cool breeze. Encouraging cool air to enter your house forces warm air out, keeping your house comfortably cool. However, this strategy only works when the inside temperature is higher than the outside temperature.
Natural ventilation maintains indoor temperatures close to outdoor temperatures and helps remove heat from your home. But only ventilate during the coolest parts of the day or night, and seal off your house from the hot sun and air during the hottest parts of the day.
The climate you live in determines the best ventilation strategy. In areas with cool nights and very hot days, let the night air in to cool your house. A well-insulated house will gain only 1° F (0.6° C) per hour if the outside temperature is 85° to 90° F (29° to 32° C). By the time the interior heats up, the outside air should be cooler and can be allowed indoors.
In climates with daytime breezes, open windows on the side from where the breeze is coming and on the opposite side of the house. Keep interior doors open to encourage whole-house ventilation. If your location lacks consistent breezes, create them by opening windows at the lowest and highest points in your house. This natural "thermosiphoning," or "chimney," effect can be taken a step further by adding a clerestory or a vented skylight.
In hot, humid climates where temperature swings between day and night are small, ventilate when humidity is not excessive. Ventilating your attic greatly reduces the amount of accumulated heat, which eventually works its way into the main part of your house. Ventilated attics are about 30° F (16° C) cooler than unventilated attics. Properly sized and placed louvers and roof vents help prevent moisture buildup and overheating in your attic.
Reducing Heat-Generating Sources
Often-overlooked sources of interior heat gain are lights and household appliances, such as ovens, dishwashers, and dryers.
Because most of the energy that incandescent lamps use is given off as heat, use them only when necessary. Take advantage of daylight to illuminate your house. And consider switching to compact fluorescent lamps. These use about 75% less energy than incandescent lamps, and emit 90% less heat for the same amount of light. Many household appliances generate a lot of heat. When possible, use them in the morning or late evening when you can better tolerate the extra heat.
Consider cooking on an outside barbecue grill or use a microwave oven, which does not generate as much heat and uses less energy than a gas or electric range.
Washers, dryers, dishwashers, and water heaters also generate large amounts of heat and humidity. To gain the most benefit, seal off your laundry room and water heater from the rest of the house.
New, energy-efficient appliances generate less heat and use less energy. When it is time to purchase new appliances, make sure they are energy efficient. All refrigerators, dishwashers, and dryers display an EnergyGuide label indicating the annual estimated cost for operating the appliance or a standardized energy efficiency ratio. Compare appliances and buy the most efficient models for your needs.
Saving Energy
Using any or all of these strategies will help keep you cool. Even if you use air conditioning, many of these strategies, particularly reflecting heat and shading, will help reduce the energy costs of running an air conditioner.
However, adopting all of these strategies may not be enough. Sometimes you need to supplement natural cooling with mechanical devices. Fans and evaporative coolers can supplement your cooling strategies and cost less to install and run than air conditioners.
Ceiling fans make you feel cooler. Their effect is equivalent to lowering the air temperature by about 4° F (2° C). Evaporative coolers use about one-fourth the energy of conventional air conditioners but are effective only in dry climates.
Many utility companies offer rebates and other cost incentives when you purchase or install energy-saving products, such as insulation and energy-efficient lighting and appliances. Contact your local utility company to see what it offers in the way of incentives.
Source List
There are hundreds of groups that can provide you with more information on natural cooling strategies. The following organizations are just a few that can assist you in keeping your cooling costs down.
Ask an Energy Expert
DOE Energy Efficiency and Renewable Energy Clearinghouse (EREC)
P.O. Box 3048 Merrifield, VA 22116
Phone: 1-800-DOE-EREC (1-800-363-3732)
Fax: (703) 893-0400
E-mail: doe.erec@nciinc.com
Consumer Energy Information Web site
Energy experts at EREC provide free general and technical information to the public on many topics and technologies pertaining to energy efficiency and renewable energy.
DOE Office of Energy Efficiency and Renewable Energy (EERE) Web site
A comprehensive online resource for DOE's energy efficiency and renewable energy information.
American Council for an Energy-Efficient Economy (ACEEE)
1001 Connecticut Avenue, NW,
Suite 801 Washington, DC 20036B
Phone: (202) 429-8873
E-mail: info@aceee.org
ASES is a professional society that fosters the exchange of information about solar energy technologies.
Cool Roofing Materials Database
Lawrence Berkeley National Laboratory The database assists with the selection of roofing materials which reflect, or otherwise reject, the sun's radiant energy, before it penetrates into the interior of the building.
Florida Solar Energy Center (FSEC)
1679 Clearlake Road Cocoa,
FL 32922
Phone: (407) 638-1000
Fax: (407) 638-1010
E-mail: webmaster@fsec.ucf.edu
FSEC is a research and education center that provides technical services and information on passive cooling strategies for hot and humid climates.
Sustainable Buildings Industry Council (SBIC)
1331 H Street, N.W. Suite 1000 Washington,
DC 20005-4706
Phone: (202) 628-7400
Fax: (202) 393-5043
E-mail: sbic@sbicouncil.org
SBIC provides practical information on energy-conscious, passive solar design and construction to the U.S. building industry.
State and Territory Energy Offices
National Association of State Energy Offices You may also contact your state and local energy offices as well as your local solar energy association for regional-specific information on natural cooling.
Reading List
The following publications provide further information on natural or passive cooling. This list does not cover all the available books, reports, and articles on passive cooling, nor is the mention of any publication a recommendation or endorsement. To obtain the publications in this bibliography, contact your local library, bookstore, or the publisher. Check the prices through your bookstore or the publisher before placing an order.
Books, Pamphlets, and Reports
- "Cooling Our Communities: A Guidebook on Tree Planting and Light-Colored Surfacing," Government Printing Office, Stock No. 055-000-00371-8, 1992.
- Landscape Planning for Energy Conservation, G.O. Robinette and C. McClennon (eds.), Van Nostrand Reinhold Co., 1983.
- Low Energy Cooling, D. Abrams, Van Nostrand Reinhold Co., 1986.
- "Measured Cooling Savings from Vegetative Landscaping," A. Meier, Proceedings of 1990 Summer Study on Energy Efficiency in Buildings, pp. 4.133 to 4.144, 1990. Available from ACEEE (see Source List above).
- "Measured Savings in Air Conditioning from Shade Trees & White Surfaces," H. Akbari et al., Proceedings of ACEEE 1992 Summer Study on Energy Efficiency in Buildings, pp. 9.1 to 9.10, 1992. Available from ACEEE (see Source List above).
- "Radiant Barriers: A Question and Answer Primer," I. Melody, Report No. FSEC-EN-15-87, 1987. Available from FSEC (see Source List above).
- "Your Home Cooling Energy Guide," J. Krigger, Saturn Resource Management, 324 Fuller Avenue, S-8, Helena, MT 59601, 1991.
Articles
- "A Comparison of Passive Cooling Techniques," G.N. Tiwari, M. Upadhyay, and S.N. Rai, Building and Environment, (29:1) p. 21, 1994.
- "Home Cooling Strategies," Consumers Digest, (31:38) p. 2, May/June 1992.
- "Keeping Cool: Natural Cooling and Air Conditioning," D. Johnson, Family Handyman, (40:3) p. 30, September 1990.
- "Passive Cooling in a Hot, Arid Climate," H.W. Arch, Solar Today, (5:2) pp. 15 to 17, March/April 1991.
- "Strategic Planting," Energy Auditor & Retrofitter, A. Meier and J. Friesen, (4:4) pp. 7 to 12, July/August 1987
|
|
|
