In the typical house 38% of all lost heat escapes though leaks and cracks in the shell of the building. That's a lot of heat and money gone with the wind. A particularly drafty house might have the air completely replaced up to 10 times every hour. Ideally the air should only refresh once every hour or two.

Though it can be difficult to find all nooks and crannies where heat is on the way out, hunting them down and plugging them up can be the most cost-efficient way to lower your energy bills. Extra bonus: any steps you take to make your house warmer in winter will also serve to make it cooler in the summer by keeping heat out.

HUNTING FOR LEAKS

You have to be a bit of detective to seek out all the chinks where drafty air is slipping in. Experts recommend using a couple of lit incense sticks for this. Simply close all your doors and windows on a fairly windy day then light your incense. Take a tour of the house, holding your incense near potentially leaky spots to see if a draft is present. You can also pay to have a "blower door" test performed by a contractor.

Some of the more common entry and exit points to look for:

- Around doors and windows

- Cracks in walls (interior and exterior)

- Attic and basement doors

- Chimney damper

- Seal between roofing and chimney

- Seal between siding and eaves

- Spaces around wall switches and outlets

- Spaces around outside taps and any plumbing the penetrates the exterior walls

- Seal between the foundation and sill

- Any place where cables, phone lines or wiring enters house

- Any place that ducting or vents penetrate the walls

The good news is that increasing your home's energy efficiency by sealing up these energy sucking gaps is the cheapest and single most effective way to save money on your heating bill. Most repairs can be done with weatherstripping and caulking which are both inexpensive.

CAULKING

A caulking gun will take care of all the most conspicuous leaks like those around windows and doors. Make sure to plug up any holes that let cables into the house, any space around taps for the garden, and the often overlooked seals between the house and the roof and foundation. For really large gaps, staple plastic sheets over the space or stuff them with strips of insulation, wood, rubber, sponge or heavy rope first, then seal with caulking. Caulking materials are flexible, paint able and should last up to twenty years.

TIP: Aerosol foam can also be used to seal large gaps like those that can be found at the foundation.

WEATHERSTRIPPING

WINDOWS: Windows that open and close will also need weatherstripping around the sash. Metal stripping is a good choice that lasts a long time and can be used in conjunction with other types of stripping to get a good seal. Viinyl or foam rubber gaskets are also popular easy to work. Felt or foam rubber strips should be attached along edge of the sash that meets with the frame to create a tight seal when window is closed.

TIP: Hanging heavy drapery that blocks the chill is another way to reduce heat loss through your windows.

DOORS: Doors will need weatherstripping around the top and sides as well as a good seal at the bottom. Cheap felt or foam rubber strips work well around door jams to create a snug fit when door is closed. Vinyl or foam rubber gaskets or interlocking jam strips can also be used here. Drafts can be kept from sneaking under doors with an easily installed door sweep or door shoe. You'll probably have to take your doors off their hinges to do this job properly.

TIP: In addition to weatherstripping all doors that lead outside, be sure to seal any doors leading to unheated or rarely heated spaces like the garage, attic and basement.

BLOCKING OTHER ENERGY SUCKERS

CHIMNEY: make sure damper is closed tightly when you're not using the fireplace. If smoke can get out, so can warm air! Also check that the flashing is doing its job.

OUTLETS & SWITCHES: seal these with special insulating inserts that block air flow.

LIGHT FIXTURES: check for leaks and caulk or otherwise seal.