Although ventilation helps to prevent dampness and decay in older buildings, too much of it can lead to uncomfortable draughts. You therefore need to strike a careful balance.
Older buildings can lose around 15-20% of their heat via draughts but there are many ways to tackle this without damaging the historic character of your building. And the good news is, such work can pay for itself very quickly.
Windows and doors
Original windows and doors are a key part of the character and interest of older buildings, and should be retained where possible. Draught-proofing is one of the cheapest and least intrusive methods of cutting down on heat lost through windows and doors, and the costs can be quickly recovered by the energy savings.
Older windows and doors often warp, and the sills, particularly of doors, are susceptible to wet rot. Check first to see if repairs are necessary, as these may help cut down on draughts.
About one fifth of a home's heating is lost through windows. Most of that escapes through air gaps rather than through the glass. Research has shown that air infiltration through a sash window in good condition can be reduced by as much as 86% by adding draught-proofing. And it has the added advantage of reducing noise and dust.
Wiper seals can be effective at keeping out draughts, especially along the base of doors, even if there is some warping. Compression seals are particularly well suited to external doors as the initial 3mm of the draught-stripping allows for seasonal movement of the door.
For further details see Draught-proofing windows and doors
Another very effective form of draught prevention is secondary glazing. This lets you keep your historic windows in place while improving their overall efficiency. If well designed, secondary glazing can be discreet and reversible.
Installing double-glazing rather than draught-proofing invariably results in the historic windows and glass being lost, and there is usually a poor visual match between the original windows and those that replace them (see Sash Windows).
For further details see Secondary glazing for windows
Chimneys can be a considerable source of draughts. Dampers can reduce draughts when flues are not in use. However, they should not be a complete fit as some air is needed to ventilate the chimney.
A cheap and effective temporary alternative is a chimney balloon, which inflates to block up the chimney. You mustn't block the flow of air altogether or permanently, however, as this could lead to a build-up of dampness in the flue.
For further details see our Open fires, chimneys and flues publication.
Gaps in timber suspended floors can also let draughts in. A quick way to reduce them is to put down a heavy rug or carpet. You could also fill in the gaps, for example by using narrow strips of timber, a clear sealant or papier mâché.
For further details see our Suspended timber floors publication.