When you are home during the day, we recommended setting your thermostat (TSTAT) at 78-degrees Fahrenheit (F) throughout the summer and at 68F during the winter.
Wait, shouldn’t that be the other way around? Actually, no. These temperatures may sound too hot or too cold for their respective seasons, but we assure you that there are a number of factors that confirm these are the best temperatures for your home.
What do these factors include? See our comprehensive article below to find out.
Is It Necessary to Keep Thermostat Temperature Constant?
Before we get into the nitty-gritty of this article, we want to first address a question we’re often asked: “Is it better to keep your thermostat at a constant temperature?”
In brief, the answer is no. There are two reasons why:
- You’ll waste money on heating if you keep the thermostat at the same temperature all winter. The same is true if you keep your thermostat constant all summer – money down the drain, a result of energy leakage from your home.
- As noted, you should keep your thermostat setting higher in summer and lower in winter in order to use your HVAC system efficiently.
Let’s take the Summer vs Winter thermostat setting first, and then we’ll look at how to cut energy throughout each season.
Higher Thermostat Temperatures in the Summer
According to the U.S. Department of Energy (DOE), the most ideal thermostat temperature in the summer is 78F. This is for a few reasons:
- Anything lower than 78F will increase your utility expenses.
- Setting your TSTAT at a lower temperature will not speed up the cooling process any more than setting it at 78F. Furthermore, if you set it at 70F, for example, thinking that will somehow cool faster (it won’t), you’ll risk excessively cooling your home, wasting energy and money.
By minimizing the difference between your indoor temperature and the outside temperature, your utility expenses will be cheaper. For this very reason, 78F is a perfect middle ground, being neither too hot (so you can be comfortable indoors) nor too cold (so you won’t overwork your central air conditioning (AC) system).
The drier your air is, the more comfortable it is at any thermostat set point. For example, 78F with 60% humidity will feel a little muggy – maybe a lot muggy!
But 78F with 30% humidity will be quite comfortable for most people. So here’s the tip: Next time you change your central AC, choose a 2-stage or variable capacity model because they remove 2-4 times as much humidity as a 1-stage central air conditioner. You’ll feel comfortable at higher temps, saving money in the process.
78 is the Lowest – Higher is OK When You Are Gone
78F is recommended for when you are home during the day. There are two other times when it makes sense to raise your TSTAT temperature higher:
- When you are sleeping. By raising the set temperature during these off-hours, you will be able to conserve more energy and, as a result, save more money. Every degree higher than 78F will save you roughly 6%-8% on your utility bills during the warm months.
- When you aren’t home for 6 or more hours at a time. You will want to raise your thermostat temperature so that the cooling system comes on at 88F.
If you want to save money but are worried that raising the set temperature will compromise your comfort, here are some ways you can stay cool:
- Use a fan(s). Portable fans are always helpful, especially in rooms without ceiling fans. Whenever you do use a ceiling fan, you will be able to raise your TSTAT temperature 4 degrees without impacting your comfort.
- Insulate your attic. Ensuring your home is properly insulated will help keep the cool air inside your home and prevent heat from entering in summer – and the reverse in winter. This same principle applies to sealing any cracks in rooms with exterior walls.
- Insulate and seal air ducts. This, of course, only applies if you own a central AC system and not a ductless mini-split AC unit. For central AC system owners, you can lose a lot of air through improperly sealed/insulated ducts. Approximately 30% of your AC system’s energy use is wasted this way.
- Avoid the stove and oven on especially hot days. Consider trading the use of these appliances for an outside grill so that you don’t heat up your home.
- Use a bathroom fan when showering. By using the fan, you can reduce the amount of heat and humidity that circulates your home.
- Purchase an Energy Star central AC system or air-source heat pump. Appliances that are Energy Star qualified are at least 15% more energy-efficient than standard market products. Having an efficient model means using less energy while easily maintaining a cool environment. For information on the best central AC brands of 2020, see our article here.
Keep an Eye on the Outside Humidity Level
Heat plus humidity is a bad combination for comfort – and in extreme conditions – safety.
One thing you will need to be careful with is setting your thermostat too high when the outside temperature is around 80F or higher and the humidity level is above 40%. If the inside temperature is too warm, you and any house plants or pets may experience heatstroke.
In this case, you should either lower the thermostat temperature below 78F or refer to the additional cooling methods in our section above.
Lower Thermostat Temperatures in the Winter
68F is an ideal temperature to set your TSTAT in the winter. According to the DOE, you can save as much as 10% a year by setting your thermostat temperature back 7F-10F from its usual setting for 8 hours a day. This process proves even more profitable for homeowners in milder climates vs. those in more extreme climates.
Alternatively, every degree higher than 68F will increase your utility bill by 4%.
You should know that 68F, just like our summer temperature recommendation, is for when you are home during the day. It will be even more cost-effective for you to lower your thermostat anywhere between 64F and 67F when you’re sleeping. As for when you are away from home for 6 or more hours, you can set your thermostat as low as 62F.
To save more on energy and finances, here are some extra things you can do to retain as much heat in your home as possible during winter:
- Clean or replace your furnace filters. You should do this once a month or as recommended by an HVAC professional.
- Clean your baseboard heaters and radiators as needed. Ensure they are not blocked by furniture, carpet, or drapes, which will limit how much heat they can discharge into a room.
- Open shades during the day; close them at night. Keep the drapes or shades on your south-facing windows open during the day to let the sunlight in, and close them at night in order to reduce the cold entering through the windows.
- Turn off exhaust fans. Make sure to turn off your kitchen and bathroom exhaust fans within 20 minutes of finishing your cooking or bathing.
- Purchase an Energy Star central heating system or air-source heat pump. To learn more about Energy Star’s specified qualifications for a central heating system, click here.
- Relocate your thermostat if necessary. Your TSTAT will read the house temperature best when it is outside of the direct sunlight and away from exterior walls. Blocking or covering your TSTAT will affect its performance, as well. If your TSTAT is presently on or by an exterior wall or frequently in direct sunlight, it’ll be in your best interest to call an HVAC professional to relocate it.
Concerning Heat Pumps
There are three main types of residential heating systems:
- Electric, gas, or oil furnaces
- Boilers and radiators
- Air-source heat pumps
Air-source heat pumps are more energy-efficient than gas furnaces or boilers since they simply transfer heat in and out of your home. But they are not as effective in harsh climates.
When the temperature outside drops to 40F or below, your heat pump has to work harder to reach your TSTAT temperature. If your heat pump has auxiliary heat (aux heat), your system will automatically turn it on as a supplementary heating source for your home. But when the aux heat turns on, your heat pump’s efficiency decreases. Why?
Aux heat is a set of electric heat strips, which uses electric resistance heating (ERH). ERH requires a lot of energy to function, and, as you know, more energy means higher heat bills.
By keeping your TSTAT set for 68F, you will prevent the heat strips from turning on.
Don’t Set Your Thermostat Temp Too Low
While it is true that lowering your indoor temperature will help you save energy and money, you shouldn’t turn the temperature too low, or you’ll risk some considerable damages.
For instance, when the temperature outside is at freezing (32F) or below, you risk freezing your pipes, which often causes them to burst and flood your home. Kitchen and bathroom pipes are specifically vulnerable to freezing since they are usually unprotected by insulation and rely on your heating system to keep them warm.
You can also risk damaging—or destroying—your furnishing and electronic equipment. How? Lower temperatures allow condensation to build up easily. An abundance of condensation will affect your wooden floors, furniture, television(s) among other furnishings and equipment.
Even houseplants and pets can be harmed if your house is consistently 60F or below or if the temperature fluctuates too greatly.
So, you might ask, what is the lowest temperature I can set my TSTAT in the winter? Our suggestion is to set it no lower than 62F when you’re away from home, presuming the temperature doesn’t drop below 32F.
When you are home during 32F-or-lower days, keep your thermostat at minimum 70F-72F.
You can find four main types of TSTATs on the market today:
- Non-programmable mechanical TSTATs, which are non-digital programmable devices that provide basic HVAC user settings.
- Smart TSTATs, which consist of multiple, convenient features on top of having programmable thermostat capabilities.
Owning a programmable digital thermostat or a smart thermostat will make your summer cooling and winter heating especially easy. These two thermostat types not only provide you more control settings than non-programmable or mechanical thermostats, but they also allow you to schedule your indoor temperatures so that they automatically change when you want them to.
This means that on top of your already busy day, you won’t need to remind yourself to reset your thermostat setting at night or the next morning, when you go to work or when you come back from work. And when you and your family are on vacation, your pre-programmed settings will allow you to leave worry-free, knowing that you won’t be dealing with excessive heating or cooling—which is always expensive.
However, there is one caveat to owning a programmable thermostats. Depending on the type of TSTAT you own, it may be incompatible with an ERH system, which electric baseboard heating uses as the main source and heat pumps use as backup or emergency heat.
Electric baseboard heating systems require thermostats that can directly control 120- or 240-volt circuits, yet only a select few companies produce line-voltage programmable thermostats. Most modern heating systems use low voltage thermostats, requiring far less than 120V to function.
Heat pumps can be compatible and energy-efficient with programmable thermostats, but it depends on the model. Some thermostats only work for heat pumps without aux heat or emergency heat (em heat).
Models that are incompatible with a programmable thermostats won’t work as efficiently when lowering the set temperature to 68F. In other words, you won’t be saving energy or money over time.
Fortunately, you can find several Ecobee, Honeywell, and Lux smart/programmable thermostat models that work well with heat pumps that have aux and em heat. Here are just a few examples:
- Ecobee3 Wi-Fi Thermostat
- Honeywell RTH6580WF
- Lux Products TX9600TS
- Honeywell RTH9585WF Wi-Fi Thermostat
If you are uncertain about your current TSTAT’s compatibility, or if you need a new thermostat, be sure to contact your most reliable HVAC company for help.