In this video, This Old House general contractor Tom Silva shows how to save money and stay warm by plugging up energy-wasting gaps, holes and cracks.

Steps:
1. Install a door sweep along the bottom of exterior doors to block out cold air.
2. Seal gaps between the door and side jambs with long pieces of weather stripping.
3. Always engage the sash locks on double-hung widows to close the gap along the meeting rail. Consider installing two sash locks on wide windows.
4. Stick a continuous length of adhesive-backed foam weather stripping to the top edge of the upper sash on double-hung windows. The soft foam will compress to fill air-leaking gaps.
5. Use foam-rubber backer rod to fill large gaps where the lower sash meets the sill. Force the backer rod into the space between the sash and stool.
6. For windows that you won't open until spring, seal them shut with temporary caulking, which you can press into place, and easily peel off when winter is over.
7. To block cold air from blowing in around an electrical outlet, remove the cover plate and press a soft-rubber gasket over the outlet. Replace the cover plate.
8. Use minimal-expanding foam to fill holes and gaps around all wall penetrations, including holes for cables, vents and pipes.