I think we still have enough local weather to justify giving tips on how to keep your house as cool as possible during these remaining hot months. Trying to remember the conventional wisdom of our grandparents but not quite sure how it goes? Window fans, for example, should they be placed to draw air in or out? Upwind or downwind of the dwelling? And what about windows, shades, and awnings? Are windows on the North side of the house better left closed or open during the day? Are awnings better than shades? These are questions that can make little battles of difference to win the war on heat and high bills.
The Consumer Guide to Home Energy Savings is a great source. They say first of all, reduce the cooling load by employing cost-effective conservation measures. Provide effective shade for east and west windows. When possible, delay heat-generating activities such as dishwashing until evening on hot days. You can help get rid of unwanted heat through ventilation if the temperature of the incoming air is 77 F or lower. (This strategy works most effectively at night and on cooler days.) Window fans for ventilation are a good option if used properly. They should be located on the down-wind side of the house facing out. A window should be open in each room. Interior doors must remain open to allow air flow. Use ceiling fans to increase comfort levels at higher thermostat settings if you have them. Actual numbers from the guide, “The standard human comfort range for light clothing in the summer is between 72 F and 78 F. To extend the comfort range to 82 F, you need a breeze of about 2.5 ft/sec or 1.7 mph. A sow-turning ceiling-mounted paddle fan can easily provide this air flow.”
A/C units go out when you need them the most. Probably because you don’t know there is a problem until you turn it on. Obvious, I know. If you have an older central air conditioner, consider replacing the outdoor compressor with a modern, high-efficiency unit. Make sure that it is properly matched to the indoor unit. If buying a new air conditioner, be sure that it is properly sized. Get assistance from an energy auditor or air conditioning contractor. Buy a high-efficiency air conditioner: for room air conditioners, the energy efficiency ratio (EER) rating should be above 10; for central air conditioners, look for a seasonal energy efficiency ratio (SEER) rating above 12.
Ventilation and using it right is great, what about not allowing the air outside to creep inside? Seal all air conditioner ducts, and insulate ducts that run through unheated basements, crawl spaces, and attics. Keep the thermostat set at 78 degrees F or higher if using ceiling fans. Don’t air-condition unused rooms. Maintain your air conditioners properly to maximize efficiency. Windows are one way air creeps in. Since most houses have a lot of them, they are a big source of unwanted heat entry. Install white window shades or mini-blinds. Mini-blinds can reduce solar heat gain by 40-50%. Close south and west-facing curtains during the day for any window that gets direct sunlight. Keep these windows closed, too.
Provide shade for your room A/C, or the outside half of your central A/C if at all possible. This will increase the unit’s efficiency by 5-10%. Clean your A/C’s air filter every month during cooling season. Normal dust build-up can reduce air flow by 1% per week. Contrary to popular opinion, turn off your A/C when you leave for more than an hour. According to the guide, several studies have found that most central air conditioning systems are oversized by 50% or more, so use it wisely. Stay cool people, stay cool.