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Ener-Gee Whiz Answers Your Questions: Thermostat Settings and Solar Water Heaters

June 23, 2009 - 12:54pm


Ener-Gee Whiz would like to offer a hearty thanks to all of you who've written in for your great efficiency and renewables related questions. Now, on to some answers!

Patti writes: Is it efficient to raise the thermostat in a business when the business is closed during air conditioning season?

Ener-Gee Whiz: Your business might be able to save energy—and money—by turning your thermostat up during the cooling season. But how much energy and money you save are largely dependent on how much you set your thermostat back and for how long. The Energy Savers website suggests that turning up your thermostat 10-15°F for at least eight hours can save an average of 10% on your cooling bills.

In a 1997 study, the Energy Information Administration conducted a more detailed analysis of possible energy savings during the heating months by setting a thermostat back one degree. Even this minimal setback, if consistent, resulted in estimated savings of $16-28 dollars per year, depending on heating fuel.

Of course, this savings is contingent on remembering to change the thermostat at the appropriate time. If you're worried about maintaining these settings for the long haul, you may want to consider investing in a programmable thermostat. Depending on the model you choose, these thermostats can be programmed with temperature settings that change several times a day and can even be set differently for weekend and weekday use. You can find more information on programmable thermostats, including a suggested daily temperature schedule, at the Energy Star Web site. Once you have a thermostat schedule in mind, Energy Star also offers a calculator (Excel 203 KB) that can help you determine your potential savings.

Karen writes: If I need a new electric hot water heater but am also considering installing a solar hot water heater in several years, can I buy a hot water heater that can become part of the solar hot water heating system later on?

Ener-Gee Whiz: Most solar water heating systems will require a backup system for cloudy days or at times of increased demand, and conventional storage water heaters are often used for this purpose. So it may be that you could purchase a new water heater now that would become part of your solar water heating system in the future. However, you may want to speak to a solar professional now to assess how any new water heater purchase might fit into any system you install later. For help locating a solar professional in your area, see the or Web sites.

Have any questions you'd like Ener-Gee Whiz to address? Leave a comment on this post asking your question; future Ener-Gee Whiz posts will try to respond to questions posed by blog readers. But please keep in mind that Ener-Gee Whiz cannot respond to technical questions pertaining to specific consumer situations; some questions just need to be addressed by a qualified contractor who can assess the situation in person.