Draught-proofing windows and doors: the cheapest winter energy fix

Leaky windows and front doors account for a surprising share of heat loss in older Swedish homes, and sealing them gives the fastest return per krona of any measure.

An afternoon of work can noticeably cut heating and remove the cold downdraught that makes sitting by the window unpleasant in January.

Finding the draughts

Hold a lit candle or a thin strip of paper along the window sash on a windy day. If the flame or paper moves, there is a leak.

The usual suspects are the bottom of the sash, the letterbox, the threshold under the front door, and cable penetrations through the external wall.

Choosing the right strip

EPDM rubber P-strips last ten to fifteen years and fit most windows. Foam strips are cheapest but dry out within a couple of seasons.

Silicone strips handle wider gaps and deep cold best, and are the standard in older timber houses in northern Sweden. Measure the gap before buying: the wrong size stops the window closing.

Restore or replace the windows

Old coupled double-glazed timber windows from before 1960 often use better timber than new ones. Restoring them with sealing plus an energy pane in the inner sash gives almost the same U-value as a new window at half the price.

A new window typically costs 6,000 to 12,000 SEK installed each, while restoration and sealing lands at 2,500 to 5,000 SEK.

What professional help costs

A tradesperson normally seals five to eight windows a day. At 500 to 750 SEK an hour, a typical house lands at 4,000 to 7,000 SEK before the ROT deduction.

Book the work in September or October. By November, carpenters in Skåne and Stockholm are already fully booked with winter preparation.