When the weather outside is frightful — like the temperatures in the single digits this weekend — it can be nice to take refuge in your warm, cozy home. Here in New England, however, older houses with outdated heating systems and less-than-modern windows are common. And, in many cases, these old-fashioned fittings can make the weather inside ­almost as unpredictable as it is outside, leaving you to wonder what surprises the next natural gas or oil bill will hold.

What’s a consumer to do in mid-winter, when every degree and every dollar counts? The answer is on your wall now.

Forget massive heating system ­upgrades or window replacements. Your thermostat can be your most useful tool, with little to no additional investment. Turn down the temp by 10 to 15 degrees when you’re out of the house or sleeping, and you can knock as much as 5 to 15 percent off your heating bill, according to the US Department of Energy.

So your savings aren’t dependent on you remembering to tweak the temperature, consider a new thermostat. A ­programmable device lets you schedule warmer and (money-saving) cooler ­periods during the day. Basic models are available for as little as $20; plenty of ­features can be had for under $100.

Or take it one step further with a smart thermostat. Depending on the model, these controllers can learn your temperature preferences, adjust them ­depending on weather, and allow you to change the temperature remotely using your phone.

Some even sense whether you are home and raise or lower the temperature accordingly. The most well-known brands include Nest, Ecobee, and Honeywell; prices generally range from $150 to $250.

If you’re still on the fence, consider this: Massachusetts residents with heating systems compatible with the smart technologies are eligible for discounts of up to 70 percent and free installation on selected brands of thermostats. More ­details are available at MassSave.com.

Don’t stop with your thermometer, though. During the day, open curtains and blinds wide to let in the sunlight — and its warmth. Make sure to clear snow around heating vents so your system can operate at its most efficient. When the heat is running, turn ceiling fans on at low speed to keep warm air circulating. Small changes can add up to noticeable savings.

Have a consumer question or complaint? Reach Sarah Shemkus at seshemkus@gmail.com.