Ask the Builder

Energy-Saving Debate: Constant Temperature, Programmed Changes, or Chilly When Vacant?

A programmable thermostat can help minimize the amount of fuel needed to keep a house warm in the winter.
A programmable thermostat can help minimize the amount of fuel needed to keep a house warm in the winter. (By Tim Carter -- Tribune Media Services)

By Tim Carter
Saturday, December 22, 2007; Page F05

Q: DEAR TIM: My heating bills are going up faster than a jet at an air show. Settle a debate among my fellow employees: Some say it is better to leave the thermostat at the same temperature all the time, as it costs so much to warm a cold house. Others say to use a programmable thermostat. Still others think the thermostat should be set at 50 degrees at night and while at work. What is the best way to save money on home heating? -- Marylyn O., British Columbia

A: DEAR MARYLYN: Heating-oil prices, as well as many other fuel costs, are going up, with little relief in sight. It's smart to think about how you can save. Still, there is no one-size-fits-all solution for keeping your home comfortable cheaply. I am reminded of a neighbor who wanted to save money. She kept her thermostat so low that I would nearly turn blue when my wife and I visited for dinner.

If you want to save a significant amount on your heating bills, then set the thermostat to 60 degrees for the entire heating season while you're awake and to 50 degrees when you are asleep. Go out and buy some long underwear, a hooded sweatshirt and maybe some light gloves. This may be a drastic change in your lifestyle, but the savings will be amazing.

Every home loses heat at a different rate, a well-insulated home being better at retaining it, of course. But, given the different source of heat a home can have, the rate and amount of heat produced can vary significantly. Keep in mind that furnaces, boilers, heat pumps and so forth come in different sizes.

To make things even more complicated, the heat produced at the point where you and I can first feel it, the floor or wall register or radiant source, can be as cool as 98 degrees with a heat pump or as hot as 125 to 130 degrees with an oil furnace. Natural gas heat can also produce high plenum or register temperatures.

Imagine letting a drafty house heated with a marginally sized heat pump drop to 55 degrees when the outdoor temperature is at 0 degrees or below. It might take hours for the house to get comfortable again with the heat pump running at full throttle. Compare that to what might happen to a super-insulated house that has a slightly oversize oil furnace. The oil furnace might get the house toasty warm in just 15 minutes.

One of the best ways to save money and remain comfortable while you're awake and at home is to install a high-quality programmable thermostat. The best ones have mini-computers that can figure out how quickly your furnace or boiler can bring your house up to the desired temperature, so as to use the minimal amount of fuel but also keep peace among those who want the house to be warm.

The trouble is, many people who have programmable thermostats do not get the full savings potential. You need to set them up to match your family's schedule. The best thermostats have settings for each day of the week, as well as vacation settings and temporary override settings. The people who save the most on their home-heating costs are those who make the furnace go up and down in temperature at least four times a day.

When programming the thermostat, keep in mind what time you are in bed each night. Since it takes the average house a while to cool off, you might program the thermostat to set back an hour before you slide under the sheets. There is no need to keep the heat on a higher setting up to the moment you fall asleep.

Tim Carter can be contacted via his Web site,

Copyright 2007 Tribune Media Services

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