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Straight Talk Articles

How Smart Should You Get? Choosing a Thermostat
January, 2018

Dear Pat, We have an old dial thermostat. There seem to be a lot of choices for thermostats nowadays. But are the pricier, more tech-focused options worth the extra cost? – Ted

           

Dear Ted,

Thermostats have some great new technology and can do things thermostats of the past couldn’t do. It’s worth asking if these new thermostats can save enough money to justify the added cost. The short answer is: Sometimes… but it depends.

 

Let’s start by looking at the three main options for thermostats: manual, programmable and smart.

 

The main benefits of a manual thermostat like yours are that it’s simple to operate and there are no batteries to wear out and replace. You just have to remember to raise and lower the temperature setting in the morning and evening and whenever you leave the house.

 

The second is the programmable thermostat. This allows settings for four different periods each day. Some models can handle a different schedule for each day of the week (1). You control the settings so they will suit your climate, schedule and temperature preferences. You can easily override your program settings anytime.

                                                                                             

The third option is a smart, or “learning” thermostat. This type connects to your home’s wi-fi network. After installation, you input basics of your schedule and temperature. Over time, as you change the settings, it learns your schedule and adjusts to minimize energy use. It’s possible for it to detect when no one is home. You can also control it remotely by using an app on your smart phone or tablet. Some smart thermostats can be equipped with additional sensors you can put in other rooms to measure for cold or hot spots.

If your co-op has a demand response program that offers discounts for using less power during peak-usage hours, a smart thermostat that allows you to participate can net you savings on your monthly power bill.

The move to smart technology is a significant investment. Units can cost up to $400, although one manufacturer has a new model for about $170. Not all homes have wiring in place to accommodate smart thermostats, and you may need to hire a professional to do the installation.

Back to your initial question: Are the more expensive new thermostats worth the extra cost? How much a thermostat can save depends on how much you spend heating and cooling your house.

You can estimate your heating and cooling expenses by examining your bills for electricity and other utilities related to heating your home. Compare the bills for winter and summer to those for spring and fall. Most of the difference is likely due to heating and cooling. If that amount comes to over $900 per year, which is the national average(2), you have a better chance of a good return on your investment.

The second factor that will determine how much you will save is how you are operating your old thermostat. If you are very conscientious about adjusting the temperature to save energy when you’re leaving the house or going to bed, the new thermostat may not reduce your bills much even if you program it correctly or if it learns your behavior.

 

Regardless which direction you go, there are a few ways you can save on your monthly energy bill:

  • Don’t crank the temperature to maximum up or down in the hopes of making it adjust quicker.

  • For the greatest savings in winter, keep the temperature at or below 68 degrees F while you are home during the day, and cooler during the night; in summer, keep it at or above 78 degrees F. while you are home(3).

  • If you heat your home by a system other than a heat pump, you can save up to 10% off your monthly heating and cooling bill by turning back your thermostat by 7-10 degrees F. for eight hours a day(4).*see below

  • The thermostat is just one piece of the energy efficiency puzzle. You might be able to save more by adding insulation or sealing air leaks. A professional energy audit is always the best way to identify your home’s energy weaknesses.

As you make your decision, don’t forget to look to your electric co-op’s website for advice, ratings and maybe even rebates!

*Heat pump users may find that electric use increases when they reduce the temperature setting on the thermostat for part of the day in the winter.  This happens because the heat pump may go into resistance mode at the end of the setback period in order to quickly increase room temperatures to the desired setting.  Resistance mode operation can be many times as expensive as heat pump mode, so it needs to be avoided.

 

There are two situations in which the heat pump user can benefit from reducing temperature settings in the winter:

1.       If the home is heated with a dual-fuel system, the heat pump can switch out of heat pump mode and the oil or propane or natural gas auxiliary heat will be used instead of electric resistance heat.

2.       If the heat pump is controlled by a sophisticated thermostat that is properly programmed it will greatly reduce resistance mode operation.  A knowledgeable HVAC contractor or supplier should be able to determine if the thermostat is capable of reducing resistance mode operation.

 

Here’s an excerpt from the Department of Energy:

“Programmable thermostats are generally not recommended for heat pumps. In its cooling mode, a heat pump operates like an air conditioner, so turning up the thermostat (either manually or with a programmable thermostat) will save energy and money. But when a heat pump is in its heating mode, setting back its thermostat can cause the unit to operate inefficiently, thereby canceling out any savings achieved by lowering the temperature setting. Maintaining a moderate setting is the most cost-effective practice. Recently, however, some companies have begun selling specially designed programmable thermostats for heat pumps, which make setting back the thermostat cost-effective. These thermostats typically use special algorithms to minimize the use of backup electric resistance heat systems.”    (https://energy.gov/energysaver/thermostats)

An efficient heat pump can often greatly reduce energy use.  To get the most savings out of a heat pump it is worth having a high quality thermostat that can greatly reduce the need for the heat pump to go into resistance mode.  It’s always wise to have heat pumps serviced regularly and to make sure the thermostat is programmed correctly.

This column was co-written by Pat Keegan and Brad Thiessen of Collaborative Efficiency.

For more information on choosing a thermostat, please visit the January 2018 more information page.

 

Footnotes

1Source: https://www.energystar.gov/products/heating_cooling/programmable_thermostats

2Source: https://www.energystar.gov/products/heating_cooling/smart_thermostats

3Source: https://energy.gov/energysaver/thermostats

4Source: https://energy.gov/energysaver/thermostats

An energy auditor demonstrates how to program a thermostat. Photo Credit: Piedmont Electric Co-Op.