Sealing and insulating your home is one of the most cost-effective ways to make a home more comfortable and energy-efficient, and you can do it yourself. A tightly sealed home can improve comfort and indoor air quality while reducing utility bills. An InterNACHI energy auditor can assess leakage in the building envelope and recommend fixes that will dramatically increase comfort and energy savings.

The following are some common places where leakage may occur:

electrical receptacles/outlets;
mail slots;
around pipes and wires;
wall- or window-mounted air conditioners;
attic hatches;
fireplace dampers;
inadequate weatherstripping around doors;
baseboards;
window frames; and
switch plates.
Because hot air rises, air leaks are most likely to occur in the attic. Homeowners can perform a variety of repairs and maintenance to their attics that save them money on cooling and heating, such as:

Plug the large holes. Locations in the attic where leakage is most likely to be the greatest are where walls meet the attic floor, behind and under attic knee walls, and in dropped-ceiling areas.
Seal the small holes. You can easily do this by looking for areas where the insulation is darkened. Darkened insulation is a result of dusty interior air being filtered by insulation before leaking through small holes in the building envelope. In cold weather, you may see frosty areas in the insulation caused by warm, moist air condensing and then freezing as it hits the cold attic air. In warmer weather, you’ll find water staining in these same areas. Use expanding foam or caulk to seal the openings around plumbing vent pipes and electrical wires. Cover the areas with insulation after the caulk is dry.
Seal up the attic access panel with weatherstripping. You can cut a piece of fiberglass or rigid foamboard insulation in the same size as the attic hatch and glue it to the back of the attic access panel. If you have pull-down attic stairs or an attic door, these should be sealed in a similar manner.
Insulate windows and doors.

About one-third of the home’s total heat loss usually occurs through windows and doors. The following are ways to reduce energy lost through windows and doors:

Seal all window edges and cracks with rope caulk. This is the cheapest and simplest option.
Windows can be weatherstripped with a special lining that is inserted between the window and the frame. For doors, apply weatherstripping around the whole perimeter to ensure a tight seal when they’re closed. Install quality door sweeps on the bottom of the doors, if they aren’t already in place.
Install storm windows at windows with only single panes. A removable glass frame can be installed over an existing window.
If existing windows have rotted or damaged wood, cracked glass, missing putty, poorly fitting sashes, or locks that don’t work, they should be repaired or replaced.