How to be energy efficient in dry climates
By Anne Prince
National Rural Electric Cooperative Association
Why does a 95°F day in one of the Gulf Coast states feel hotter than the same temperature in the Southwest? Why do dry heat and humid heat feel so different, and how does this affect your strategy for an energy efficient home? While there are many common ways to achieve energy efficiency across all warmer climates, there are some important differences that vary by geography.
Dry heat vs heat and humidity
Generally speaking, when there is more moisture in the air, the temperature feels hotter than it actually is because moist air is closer to saturation than dry air. On a humid day, when the air is saturated with water, evaporation is much slower. Simply put, high humidity will make the air feel hotter while low humidity will make the temperature feel cooler.
Heat reduction is priority one
In warm climates, the majority of energy used to make the home feel comfortable is spent on home air conditioning and cooling. The first priority is heat reduction. However, in humid areas, moisture reduction is nearly as important as lowering the indoor air temperature. If a home has too much moisture, indoor air quality can be comprised and mold and mildew problems can develop. This is especially critical to families with allergy sufferers.
Energy efficiency for hot and dry climates
In hot, dry climates, you are battling the blazing hot sun, which heats up the surface of your home. As the heat beats down on your home’s roof, windows and walls, the heat conducts to the inside. However, there are some basic steps you can take to make your home more comfortable and energy efficient in hot, dry climates.
Starting from the top, it makes sense that light colored roofs reflect the sun’s heat away from the home, whereas a dark color absorbs the heat. Make sure you have a vented area directly under your roof to allow some of the heat to dissipate and reflect back. A vented roof effectively shades the rest of the home. It is also important to properly seal your home’s thermal envelope. Leaky ducts, windows and doors can cause energy loss, making the HVAC system work much harder and drive up your energy costs. It pays to seal windows, doors and duct work. According to the Dept. of Energy, on average, households lose approximately 20 percent of their heated and cooled air through the duct system to the outside. Homes that are “sealed tight” are easier to keep cool and dry.
Strategic landscaping can also make a big difference in hot climates. In addition to the aesthetic value, well placed trees can take heat gain from the sun and provide shade by creating a canopy for the home. While occasional trimming, pruning and replacement may be necessary, properly placed trees can potentially save between $100 and $250 annually.
Indoors, where possible, shade windows that don’t have a deep overhang. Using a ceiling fan in conjunction with your AC allows you to increase the thermostat setting to approximately 4°F with no reduction in comfort. In hot climates, it’s all the more critical to replace any remaining incandescent bulbs with LEDs, as the waste heat from the old bulbs impacts energy use and creates unwanted heat. In addition, move TVs and lamps away from the AC thermostat. The thermostat senses heat from the appliances and may cause the AC to run longer than needed.
Anne Prince writes on consumer and cooperative affairs for the National Rural Electric Cooperative Association, the Arlington, Va.-based service arm of the nation’s 900-plus consumer-owned, not-for-profit electric cooperatives.