Leave the deerstalker hat and magnifying glass behind. All you’ll need for energy sleuthing is a flashlight, screwdriver, paint stirrer, tape measure, and—not just for serenity’s sake—a stick of incense.
 
1. Hunt down drafts. Hold a lit stick of incense near windows, doors, electrical outlets, range hoods, plumbing and ceiling fixtures, attic hatches, and ceiling fans in bathrooms—anywhere drafts might sneak in. Watch for smoke movement. Note what sources need caulk, sealant, weather-stripping, or insulation.

2. Check attic insulation. Winter or summer, insulation does the most good when it’s overhead, so start with the attic. First, do you have insulation? If the insulation you see covers the tops of the joists by several inches, you probably have enough. If the insulation is only even with the tops of the joists, you probably need to add insulation.

3. Check wall insulation. Remove electrical outlet covers to see if your wall contains insulation. Shut off power to the receptacle before probing beside the electrical box with a wooden paint stirrer. Check some switch boxes as well. Their higher wall location lets you see if blown-in insulation has settled.

4. Look for stains on insulation. These often indicate air leaks from a hole behind the insulation, such as a duct hole or crack in an exterior wall. Seal gaps with caulk or spray foam insulation.

5. Inspect exposed ducts. Look for obvious holes and whether joints are sealed. Heating, ventilation, and cooling (HVAC) ducts are made of thin metal and easily conduct heat. Consider insulating them. Uninsulated or poorly insulated ducts in unconditioned spaces can lose 10% to 30% of the energy used to heat and cool your home.

6. Check anything that goes through an exterior wall. Examine dryer ducts, plumbing lines under sinks and vanities, anything that pierces a wall. Any gaps around it should be sealed with spray foam insulation or caulk.