Test your thermostat
Risk: If the temperature in your house isn’t what shows on the
thermostat, your air conditioner or furnace could be working too hard.
How to DIY it: Every spring and fall, tape a household thermometer on the wall next to the thermostat. After about 15 minutes, compare readings. If the difference between the two numbers is more than a few degrees, try recalibrating your thermostat (follow the manufacturer’s instructions).
While you’re at it: If you don’t have a programmable thermostat, consider getting one. According to the U.S. Department of Energy, an Energy Star–rated model can save you about $180 in heating and cooling costs each year. You can buy one for about $40 and install it yourself. It’s a relatively easy job; no rewiring required. On the other hand, these are home improvement projects you should never, ever DIY.
Stop air leaks under doors
Risk: Cooling or heating the
world outside your home is obviously wasteful—and expensive.
How to DIY it: Most door thresholds (also called a saddle; below) adjust up and down with screws. Turn all the screws equally until the door opens and closes without much drag and the draft is eliminated.
While you’re at it: You can seal drafty windows with removable caulk, which will keep cold air outside in winter and easily peel off come spring.