My first winter heating bill after moving into an older house made me choke on my coffee. I did not have thousands of dollars for new windows or insulation, so I started with the cheap fixes. The bill dropped enough that I actually kept a spreadsheet.

Seal the leaks first, because heat leaves through them

Drafty windows and doors are the biggest heat thieves, and they are the cheapest to fix. Weather stripping around doors costs a few dollars per door, and window film kits run about ten dollars per window. Both take under an hour to install. I sealed my front door and the two draftiest windows one weekend and could feel the difference immediately.

Use the thermostat like it owes you money

Set the thermostat a few degrees lower when you sleep and when you are out of the house. A programmable thermostat does this automatically, and the basic ones are cheap. Dropping the temperature by seven degrees for eight hours can cut heating use by about ten percent. I keep mine at sixty-eight when home and sixty-two at night, and I sleep under a heavier blanket instead of paying to heat the air above it.

Check the filter and the vents

A dirty furnace filter makes your heating system work harder and run longer. Replace it at the start of the season and check it monthly. Walk around and make sure furniture and rugs are not blocking the heat vents. Blocked vents do not save heat, they just make the furnace run longer to push air that never reaches the room.

The sneaky savings

• Close the doors to rooms you rarely use and shut their vents partway.
• Open curtains on sunny windows during the day to let sunlight in, then close them at dusk to trap the warmth.
• Put a draft stopper under the door to the garage or basement.
• Lower the water heater temperature a few degrees. It saves energy without changing your shower.

None of these are glamorous, but they add up fast. The cheapest energy is the energy you do not use, and most homes waste a surprising amount of it through small leaks and bad habits. My second winter in that house cost noticeably less, all from fixes under twenty dollars each.