Evaporative Coolers Save Energy and Money

Fan blowing water mist provides evaporative cooling effect.

This is NOT an example of an evaporative cooler!

Keeping cool can be a challenge during our hot summers, especially when faced with high energy bills. Modern air-conditioning systems use a lot of power and that’s why making our homes more energy-efficient can be so rewarding. Efficiency can only go so far though, so it’s good to have other options for chilling-out while saving some dough.

One of the most effective ways to reduce summer cooling costs is to install a high-efficiency evaporative cooler. They require a small fraction of the energy used by an air-conditioner and are well-suited for our dry climate. There are many makes and models, from whole-house units to devices that fit in a window. They can shave hundreds of dollars a year from your energy bill.

Modern evaporative coolers are simple devices that take in outside air, pass it through a permeable water-soaked membrane and blow it into the house at a much cooler temperature. They depend on evaporation to provide the cooling effect and work best when humidity is low. They add moisture to the cool air coming into the house, an added benefit that is often appreciated. Conversely, there are some days, even in the Mojave Desert, when the summer monsoon brings high humidity and a conventional air-conditioner becomes the best option.

Because an evaporative cooling system pressurizes the house, it requires an open door, window or attic vent to allow warmer, stale air to escape. By adjusting which doors and windows are open, one can control where most of the cooler air flows, optimizing comfort where needed. Because so much fresh air enters the home, these systems are especially well-suited for older, less efficient homes or even manufactured homes that often use inordinate amounts of energy to maintain comfortable temperatures.

As with most things in life, there are trade-offs. Evaporative coolers require seasonal maintenance and the cooling pads must be changed periodically, but the benefits are well worth it. They also use water, a precious resource in Southern Nevada. But that’s not the whole story.

Water and energy are joined at the hip. Every commercial electric plant uses water to operate; therefore every electrical device we use is also using water – somewhere. There are many factors involved in comparing water use and energy (see Consumptive Water Use for U.S. Power Production (PDF), NREL – Table 3. United States Water Consumption per kWh of Energy Consumed by State), but in simple terms saving energy also saves water. According to reports by the Southwest Energy Efficiency Project (see Evaporative Cooling Policy and Program Options: Promising Peak Shaving in a Growing Southwest (PDF) May 2004 and New Evaporative Cooling Systems: An Emerging Solution for Homes in Hot Dry Climates with Modest Cooling Loads (PDF) April 2004), an evaporative cooling system in Las Vegas will raise local water consumption by around 2.6% on average, but because they save so much energy, the overall impact on water use is minimal.

I once helped an older couple who was on a fixed income. They were considering a solar screen package which would have provided only marginal savings, along with a darker interior. Instead, they opted to install an in-wall evaporative cooler in a centrally-located room at about the same price. By adjusting doors and windows, they soon learned how to keep any part of their home comfortable, depending on their needs. They loved the fresher, less-dry air and reluctantly used the AC on only the hottest, most humid days. Their energy bills plummeted and they were extremely happy with their decision. Plus their home’s natural daylighting remained intact, keeping things bright and cheerful. Green Living can work for everyone!