It`s a long, hot summer here in Louisiana. While air conditioning units provide relief, these systems can really cause your energy bills to heat up. Natural or passive cooling is a money-saving and environmentally friendly alternative where unwanted heat is reflected, blocked, or removed. While they may not completely replace your air conditioning system, passive cooling techniques can increase comfort and reduce your summer energy costs.
Roof. Your roof becomes really hot in the summertime and much of this heat filters into your home. Reflective roof coatings can reduce summer energy use and make your home more comfortable. These products, which can be applied over most existing roofs, block the ultraviolet rays of the sun, extending the life of most roofing materials, and reducing surface temperatures by as much as 80ÂºF. If you are considering a new roof, make sure to install ENERGY STAR rated cool roof products. ENERGY STAR products can reduce your cooling energy use by 10 to 15 percent.
Windows. Much of the unwanted heat that builds up in your home on hot summer days enters through the windows. Reflective window films deflect up to 97 percent of infrared heat away from the inside of your home, while reducing the fading of furniture, draperies and carpeting.
Landscaping. Leafy trees planted on the south and west sides of your home will provide cooling shade in summer, blocking heat gain through your roof and
windows. A six- to eight-foot tree planted near your home will provide shade for windows during the first year. Depending on the species and the roof, a tree will provide roof shading within 5 to 10 years. Shrubs and ground cover will help shade the ground and pavement around your home. This reduces heat radiation and cools the air before it reaches your walls and windows. For more information, see Landscaping from the U.S. Department of Energy.
Shading devices. Exterior shading devicesâ€”awnings, louvers and shuttersâ€”block direct sunlight, reducing solar heat gain. Installing awnings on windows with a southern exposure, for example, can reduce solar heat gain as much as 65 percent. Interior shading devicesâ€”draperies, blinds or shadesâ€”are also effective at blocking solar heat gain.
Natural ventilation. A cool breeze feels great on a hot day, and it is a great way to force warm air out. Open windows during the coolest part of the day or night and seal off your house from the sun and warm air during the hottest part of the day. Ventilated attics greatly reduce accumulated heat, and are up to 30Â°F cooler than unventilated attics. Properly sized and placed louvers and roof vents help prevent heat buildup and moisture in your attic.
Heat generating sources. Often overlooked is the heat buildup from lights and appliances, such as water heaters, ovens and dryers. Conventional incandescent bulbs give off much of their energy as heat. Replace them with compact fluorescent lamps (CFLs); not only are CFLs highly efficient, but they emit 90 percent less heat. Avoid using heat generating appliances during the hottest part of the day, and seal off your laundry and mechanical room from the rest of the house.
While passive cooling methods can provide cost-effective relief from the heat, most homes require some supplemental cooling. Ceiling fans create air circulation in a room to make it feel cooler, reducing the need for air conditioning. A whole-house fan draws cool air into your home through open windows, while pulling hot, indoor air to the attic and exhausting it outside.