The wind blows where it pleases; you can hear its sound, but you cannot tell where it comes from or where it is going.

John 3:8

Do you have the wind whistling through your room and find it hard to keep warm? When you can feel the cold air flowing past you even when the windows are closed then it is possible you have too much air movement. Having a few air changes every so often is actually important for ventilation and keeping the house or flat habitable. This is the reason for trickle vents on windows, for example. However if you are in an older property and the air currents are noticeable and perhaps you can feel the chill from misfitting windows and doors, then it is likely that you have too many air changes and draughts (drafts) are an issue for you. It can be expensive to fix an old property and if you rent it might be hard to persuade your landlord to fix it for you. So a practical method to make things a little better can be to place a roll of fabric next to the source of the air current. Typically these air currents may be noticeable at the base of external doors and around windows. Old unwanted clothes or fabric offcuts from local retailers may be just what is needed. Remember to move them every so often, especially if the windows and doors get condensation dripping down on to them as you don’t want them to start to grow mould on them.

A typical dwelling which is adequately ventilated may have between 0.15 and 1 air changes per hour. Air changes per hour relate to the number of times the entire volume of air in the house or flat is replaced every hour. Although this sounds like a waste of energy, this level of air change is not particularly high and it doesn’t invalidate the necessity for good thermal insulation (the new air is rapidly heated up in a well insulated property by your heating system for only a small penalty). Higher air changes are required in kitchens and bathrooms with most dwellings having mechanical extractor fans operating when cooking or showering.

Incidentally, if major energy efficiency works are done on a property then paying attention to ventilation requirements is necessary. In the UK, updated guidance is in the form of Approved Document F available through gov.uk. New high efficiency buildings such as PassiveHouse will need mechanical ventilation systems to maintain healthy indoor oxygen and carbon dioxide levels (the best of these will be with heat recovery to prevent the exhaust air taking too much valuable heat with it). Retrofit on old dwellings may need additional ventilation over and above that provided by passive infiltration ventilation.