[DickR]

If you tentatively decide on a house, but wonder just how leaky (ie. drafty and uncomfortable) it may be, one of the things you could pay to have done as part of inspection is a blower door test. A fabric-covered adjustable frame is fit tightly into an open door, and a fan is mounted in that frame. The fan is turned on to depressurize the house slightly and an instrument shows the amount of air (cubic feet/minute) needed to maintain a standard pressure difference (50 Pascals - quite small, so as not to cause any harm). That flow, times 60, is divided by the gross house volume to give standard air changes per hour (ACH), and that divided by a factor around 18 gives an approximation of "natural" ACH in cold, windy weather. The tester will be able to relate that in relative terms to "tight," average, or "leaks like a barn with the door open."

You'd want to be around for the test if possible, to take copious notes. Part of the testing may well include flagging the major sources of air leakage. Such places often are so easy to seal with canned foam or non-hardening sealant. Air leakage plays a HUGE role in the cost of heating a house in a cold climate, far more than many realize. A leaky house in otherwise good condition could well be turned into a very comfortable place with acceptable heating cost with relatively little effort, much of which you can do yourself if you are willing to crawl around in old clothes and a dust mask.