Programmable Thermostats Are a Great Way to Control Energy Costs

With energy-efficient options such as new HVAC equipment, remodeled ductwork and programmable thermostats, energy costs in your home will definitely fall. Some methods of saving require significantly greater up-front investment than others. Programmable thermostats, one of the least expensive upgrades you can have installed in your home, can provide an excellent return on investment and help control energy costs.

Programmable Thermostats Defined

A typical, outdated thermostat was a mechanical device with a bimetal coil inside. The two metals expanded and contracted at different rates so that, as temperatures rose and fell, the coil unwound or contracted. When attached to a mercury-filled glass bulb, this coil helped complete an electrical circuit, activating your home’s furnace or central air conditioner. This was very primitive, and offered no programming at all. You set it for 70 degrees during winter. It ran your furnace day and night.

Programmable thermostats, by contrast, have printed circuit boards, computer memories and screens allowing various features and settings. These are programmed just as you apply settings on alarm clocks, microwave ovens and car stereos. You set daytime and nighttime temperatures for both winter and summer. When programmable thermostats are used properly, your fuel bills will drop.


When considering buying and installing programmable thermostats, energy costs should play a significant role in your calculations. While several types—including large screen, easy reading designs—are available, the market is dominated by three:

  • 5+2-day models—If you live a fairly predictable life, where the same schedule can apply for each of the weekdays and another schedule for both weekend days, this is the model for you. You will be able to set four temperature periods for all five weekdays—morning, empty house, afternoon, overnight—and the same four with different times for the weekend.
  • 5-1-1 models—While your weekdays may be regular, if you have varying schedules Saturday and Sunday, you can use this model to differentiate the two weekend days.
  • 7-day models—These are the most flexible models, so that each of seven days can be set independent of the others. Each day will include four temperature periods (waking, empty house, afternoon, overnight).

Programmable Thermostats Get Bad Press

When these devices first came on the market, they received widespread support both by government agencies and industry. These energy-efficient tools were going to lower America’s energy consumption, helping to reduce our dependency on foreign oil. Programmable thermostats would improve homeowners’ comfort, reducing the need for heavy sweaters in winter while still keeping us cool in summer.

The problem was that, after homeowners installed programmable thermostats, energy costs did not automatically plummet. This led many consumers to feel that the hype about these simple energy tools had no basis in science. Unfortunately, the hype oversimplified their correct use. The chatter ignored the important detail that controlling energy costs depended on consumers installing and setting the devices correctly. Most homeowners did not put them in or use them as the instructions recommended.

Energy Costs Fall

With programmable thermostats, energy costs will only decline if the devices are installed and programmed according to directions. The best way to ensure this is through professional installation. If you are determined to install the thermostats yourself, be certain to place them according to strict guidelines:

  • On interior walls
  • Away from windows and doors
  • Out of direct sunlight
  • Away from registers and vents

In addition to location, correct programming is the key to lowering energy costs. In winter, all your home’s programmable thermostats should be set for no more than 68 degrees when you are awake and home. For empty house and overnight settings, this should drop by at least ten degrees, so your home’s furnace will not start up until the temperature drops to 58 degrees. This seems cold, of course, but your furnace will work no harder to warm your home in the morning to bring it up from 58 degrees than if it ran all night to maintain the higher temperature. Energy savings start to add up when your furnace is idle for eight or more hours a day.

In summer, setting the central air conditioner to cool when the temperature climbs above 76 degrees when you are home, and 86 degrees overnight and when you are out, will similarly lower your electrical bill.

Money, Money

According to the U.S. Department of Energy, your savings from programmable thermostats can be as much as 15 percent off your current heating bill. This means you save roughly one percent for every degree of setback (the lower temperature overnight and when your home is empty) for every eight hours.

Similarly, you will cut your electricity costs for central air conditioning when the system allows temperatures to climb for eight hours.


Since homeowners are either not present or are unaware (because they are asleep) when the programmable thermostat allows winter temperatures to fall steeply, they may feel no evidence that the device is working. Since most of these units have a type of fuzzy logic that anticipates need, in the morning (for example) they will call for heat early so that, when the homeowner wakes, the house is warm again. Unless you find yourself unexpectedly awake in the wee hours, you will never know your home’s winter temperature dropped. This also holds true when you are not home during the daytime.

Similarly, during the summer the central air conditioner will not cool your home overnight. Again, unless you set up vigil to monitor the rising temperatures, you will sleep through the ten-degree climb while still waking to a comfortably cool home.

This inability to observe the energy-saving settings in action leads people to assume the programmable thermostats are not working. Give the programmable thermostats time to cycle through at least a week of settings, though, and you will soon see falling energy costs. Since you are setting the desired temperature for a desired time, the system “learns” to start the furnace or central air conditioner to meet that target.


To make the most of programmable thermostats, have your trusted HVAC contractor install them for heating and cooling zones. Each area of your home is controlled by one thermostat.

Typical zones are separate floors, different ends of a large home, or a special-needs bedroom apart from the rest of the house. This way, the seldom-used basement can be heated and cooled less frequently, with greater temperature differentials, than the main parts of your home. An elderly family member’s room can be kept warmer than most family members would prefer.

With all zones of your home controlled by programmable thermostats, energy costs will fall when each thermostat is set to provide a substantial difference between daytime and nighttime temperatures.

Extreme Programming

Whether you bring in a professional or you install your own programmable thermostats, energy costs must fall sufficiently to provide a reasonable return on your investment, though the costs of programmable thermostats are significantly less than the costs associated with replacing furnaces or central air conditioners. You can make the most of these savings by pushing the envelope when having an HVAC contractor set up the devices (or attempting it yourself):

  • Have the setbacks (the empty house and overnight temperatures) placed at 15 degrees’ difference: 53 degrees during winter and 91 degrees during summer
  • Extend the setback periods by up to two hours—the more time your HVAC equipment is idle, the greater your energy savings
  • Place the morning and occupied settings for slightly less (in winter) and more (in summer) than the usual recommendations: 66 or 67 degrees in winter and 78 or 79 degrees in summer
  • Use the unit’s “Hold” or “Vacation” feature to set a 24-hour energy-efficient temperature when you know you will be gone more than one day
  • Avoid overriding the settings—keep family members from adjusting the programmable thermostat

Professional Installation

The easiest way to ensure correct installation, programming and zoning is to hire a trusted HVAC contractor. While big-box stores may offer programmable thermostats for do-it-yourself handy homeowners, using a contractor has several advantages:

  • Warranties are upheld on all equipment (furnace, central air conditioner and programmable thermostat)
  • One company handles all your HVAC needs, knowing your system thoroughly
  • System balancing can be adjusted by the technician
  • Ideal energy-saving settings will be programmed
  • Knowledgeable if installation problems arise
  • New heating and cooling zones can be incorporated during installation

With the simple use of programmable thermostats, energy costs for your home can be more precisely controlled by you, despite wide fluctuations in outside temperatures or an uncertain fuel commodities market. To learn more about the many ways correctly installed and set programmable thermostats can help lower your home’s energy costs, contact Custom Mechanical.

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