Summer Cooling Tips
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Massachusetts Department of Energy Resources SUMMER COOLING TIPS Deval L. Patrick Governor Timothy P. Murray Lieutenant Governor Ian A. Bowles Secretary, Office of Energy & Environmental Affairs Phillip Giudice Commissioner, Division of Energy Resources EASY WAYS TO CONSERVE • Remember that light colors • Postpone doing laundry and reflect heat and dark colors dishwashing until nighttime KEEP absorb it. to avoid peak-electric use hours. Hang laundry outside • Close draperies or shades to dry. COOL during the day to block the sun especially on windows • Use the air-dry feature on AND that face south or west. dishwashers. Open them in the evening to SAVE let cool air in. • Service air conditioners annually and be sure the air • Keep cool air in by conditioner is the right size ENERGY! installing insulation and for the area. Change the weather-stripping. filter regularly. Choose an air conditioner with the • Turn off lights when not in Energy Star label when use. Switch incandescent buying a new one. bulbs to cooler compact fluorescent ones. • Turn the air conditioner thermostat up to at least 78" • Cook on the grill to keep or higher or use a cooking heat outside. When programmable thermostat. using the stove, vent Close doors to unused cooking heat outside with a rooms. Turn air conditioners range hood. off when no one is home. APPLIANCE USE • Use an attic fan to draw hot air out of the attic. Use a • Use a microwave instead of whole-house fan to draw an oven. Microwaves use fresh air in through windows less than half the power of a and exhaust it out roof vents. conventional oven and cook food in about one-fourth the • Use ceiling fans to circulate time. Ovens also heat up the air kitchen, making your cooling system and refrigerator work harder. HOME ENERGY USE Keeping cool indoors when it is REFLECTING HEAT AWAY hot outdoors is sometimes difficult. The sun beating down on Dull, dark-colored home exteriors our homes causes indoor absorb 70% to 90% of the radiant temperatures to rise to energy from the sun that strikes COOLING uncomfortable levels. Air the home's surfaces. Some of this conditioning provides some relief. absorbed energy is then transferred YOUR But the initial costs of installing an into your home by way of air conditioner and the electricity conduction, resulting in heat gain. HOME costs to run it can be high. In In contrast, light-colored surfaces addition, conventional air effectively reflect most of the heat conditioners use refrigerants made away from your home. NATURAL of chlorine compounds, suspected contributors to the depletion of the ROOFS LY ozone layer and global warming. About a third of the unwanted heat that builds up in your home comes But there are alternatives to air in through the roof. This is hard to conditioning. This publication control with traditional roofing provides some common sense materials. For example, unlike suggestions and low-cost retrofit most light-colored surfaces, even options to help you "keep your white asphalt and fiberglass cool"—and save electricity. shingles absorb 70% of the solar radiation. STAYING COOL One good solution is to apply a An alternative way to maintain a reflective coating to your existing cool house or reduce air- roof. Two standard roofing conditioning use is natural (or coatings are available at your local passive) cooling. Passive cooling hardware store or lumber yard. uses nonmechanical methods to They have both waterproof and maintain a comfortable indoor reflective properties and are temperature. marketed primarily for mobile homes and recreational vehicles. The most effective method to cool your home is to keep the heat from One coating is white latex that you building up in the first place. The can apply over many common primary source of heat buildup roofing materials, such as asphalt (i.e., heat gain) is sunlight and fiberglass shingles, tar paper, absorbed by your house through and metal. Most manufacturers the roof, walls, and windows. offer a 5-year warranty Secondary sources are heat- generating appliances in the home A second coating is asphalt based and air leakage. and contains glass fibers and Specific methods to prevent heat aluminum particles. You can apply gain include reflecting heat (i.e., it to most metal and asphalt roofs. sunlight) away from your house, Because it has a tacky surface, it blocking the heat, removing built- attracts dust, which reduces its up heat, and reducing or reflectivity somewhat. eliminating heat-generating sources in your home. Another way to reflect heat is to Many of these films are tinted, install a radiant barrier on the however, and tend to reduce light underside of your roof. A radiant transmission as much as they barrier is simply a sheet of reduce heat, thereby darkening the aluminum foil with a paper room. backing. When installed correctly, a radiant barrier can reduce heat Combination films allow some gains through your ceiling by light into a room but they also let about 25%. some heat in and prevent interior heat from escaping. These films Radiant-barrier materials cost are best for climates that have both between $0.13 per square foot hot and cold seasons. Investigate Replacing a 10-year- ($1.44 per square meter) for a the different film options carefully old room air single-layer product with a kraft- to select the film that best meets paper backing and $0.30 per your needs. conditioner with a square foot ($3.33 per square new ENERGY STAR meter) for a vented multi-layer Note: Do not place reflective qualified model saves product with a fiber-reinforced coatings on south-facing windows an average of $14 a backing. The latter product if you want to take advantage of doubles as insulation. heat gain during the winter. year on your electric bill. WALLS LANDSCAPING Wall color is not as important as Landscaping is a natural and roof color, but it does affect heat beautiful way to shade your home gain somewhat. White exterior and block the sun. A well-placed walls absorb less heat than dark tree, bush, or vine can deliver walls. And light, bright walls effective shade and add to the increase the longevity of siding, aesthetic value of your property. particularly on the east, west, and When designing your landscaping, south sides of the house. use plants native to your area that survive with minimal care. WINDOWS Deciduous trees that lose their Roughly 40% of the unwanted leaves in the fall help cut cooling heat that builds up in your home energy costs the most. When comes in through windows. selectively placed around a house, Reflective window coatings are they provide excellent protection one way to reflect heat away from from the summer sun and permit your home. These coatings are winter sunlight to reach and warm plastic sheets treated with dyes or your house. The height, growth thin layers of metal. Besides rate, branch spread, and shape are keeping your house cooler, these all factors to consider in choosing reflective coatings cut glare and a tree. Vines are a quick way to reduce fading of furniture, provide shading and cooling. draperies, and carpeting. Grown on trellises, vines can shade windows or the whole side Two main types of coatings of a house. Ask your local nursery include sun-control films and which vine is best suited to your combination films. Sun-control climate and needs. films are best for warmer climates because they can reflect as much as 80% of the incoming sunlight. Besides providing shade, trees and Maintaining a gap between the top vines create a cool microclimate of the awning and the side of your Source List that dramatically reduces the house helps vent accumulated heat temperature (by as much as 9° F from under a solid-surface awning. Ask an Energy Expert [5° C]) in the surrounding area. If you live in a climate with cold DOE Energy Efficiency and Renewable Energy During photosynthesis, large winters, you will want to remove Clearinghouse (EREC) amounts of water vapor escape awnings for winter storage, or buy P.O. Box 3048 through the leaves, cooling the retractable ones, to take advantage Merrifield, VA 22116 passing air. And the generally dark of winter heat gain. Phone: 1-800-DOE-EREC (1- and coarse leaves absorb solar 800-363-3732) radiation. The amount of drop (how far TDD: 1-800-273-2957 down the awning comes) depends Fax: (703) 893-0400 You might also consider low on which side of your house the E-mail: [email protected] ground cover such as grass, small window is on. An east or west Consumer Energy Information plants, and bushes. A grass- window needs a drop of 65% to Web site Energy experts at EREC covered lawn is usually 10° F (6° 75% of the window height. A provide free general and C) cooler than bare ground in the south-facing window only needs a technical information to the summer. If you are in an arid or drop of 45% to 60% for the same public on many topics and semiarid climate, consider native amount of shade. A pleasing angle technologies pertaining to ground covers that require little to the eye for mounting an awning energy efficiency and water. For more information, see is 45 degrees. Make sure the renewable energy. Landscaping for Energy awning does not project into the Efficiency. path of foot traffic unless it is at DOE Energy Efficiency and least 6 feet 8 inches (2 meters) Renewable Energy Network SHADING DEVICES from the ground. (EREN) A comprehensive online resource for DOE's energy Both exterior and interior shades One disadvantage of awnings is efficiency and renewable control heat gain.