Summer is here, with a pattern of hot weather and high humidity. Through good design and smart operation of homes, we should be able to minimize the use of central air conditioning as the primary method of keeping ourselves cool. Here are the top 10 strategies for home design to minimize air conditioning needs; some apply only to new construction while others apply also to renovations. These are not ranked by priority.
1) If the site permits, more of the windows should face south than north. During the summer, most sunlight enters through east-or west-facing windows. It may also be possible to orient the house to benefit from summer breezes.
2) Shade south-facing windows with fixed overhangs, since the sun is higher in the sky in the summer than in the winter. They will help to cool in the fall months as well, because although the sun is lower in the sky, the outdoor temperature may still be high. Use vertical louvres, exterior roller screens, operable awnings, and plantings for shading on east and west windows. Fixed overhangs will not work well for shading on these windows, since the sun stays low during the day. Shading windows on the exterior rather than the interior is better, as it keeps out more unwanted heat.
3) Control unwanted solar gain by installing south side windows with glass containing a high solar heat gain coefficient of .5 or .6 (SHGC) to bring in solar heat during the heating season, and use low SHGC glass of .3 or lower on the east and west.
4) Install lots of insulation in the building envelope to minimize unwanted heat gain which can enter through the walls and roof. Keep the house airtight in order to keep heat out during the day when the house is closed up.
5) A light colored, reflective roof with high emissivity may also help to keep unwanted heat out of your house. A bright, galvanized metal roof is reflective but has low emissivity, which can cause unwanted heat. Look for roof materials certified by the Cool Roof Rating Council or the Energy Star Roof Program.
6) Providing thermal mass in the house, such as a brick chimney, plaster walls, or slate floor, can reduce air conditioning requirements by helping to keep a house interior from getting too hot during the day, as heat is absorbed by these high-mass materials during the daytime.
7) Due to humidity, house design for passive cooling should provide for no moisture seepage into house, and have proper flashing to avoid rain entry. There should be bathroom fans to exhaust excess moisture, and these fans should be quiet to increase the likelihood that they will be used.
8) In order to ventilate the house, exchange warmer indoor air with cooler outdoor air by closing up a house during the day and then carrying out “night flushing”. Enough operable windows must be provided in order for this to be efficient. An outlet vent high in the building and a specialized cooling chimney can be very helpful, as well as whole-house fans, in hot regions where the night temperatures drop, such as the Southwest.
9) Fluorescent and LED lights produce much less unwanted heat than incandescent lights, which convert only about 10% of electric current into light; the rest is emitted as heat. More efficient large appliances, such as refrigerators and dishwashers, also produce much less unwanted heat.
10) Ceiling fans, which keep us cool by increasing evaporation from our skin, may keep us comfortable with air temperatures as much as five degrees Fahrenheit warmer than will still air. This may reduce the time that mechanical air conditioning is needed.
When you are ready to redesign and remodel your home to keep its cool, please call ReBuilders, Inc. at 843-448-0041. You may also visit our website at www.rebuildersmyrtlebeach.com.
Wilson, Alex. “Designing Houses That Keep Their Cool”, paraphrased. Energy Solutions: Rethinking energy. Rethinking solutions. 4 July 2013. Web.