Stopping draughts is cheap and extremely effective.
“If you seal a building, you can increase its energy efficiency by 30 to 40 per cent,” says environmental building consultant Jan Brandjes. “Whenever there’s a slight pressure difference between inside and outside, air will always travel through gaps. It’s like a pinhole in the bottom of an aquarium.”
Because of draughts, the air in an average Victorian house is replaced 1.5 times every hour on a calm day, according to Mr Brandjes. In strong winds, the exchange rate can be up to 20 times per hour. “Fixing air leakage is the cheapest and easiest way to save energy,” he says.
Common leaks include exhaust fans, wall vents, downlights, and chimneys and evaporative coolers (without dampers). There are usually cracks around doors, windows, skirting boards, cornices and floorboards. Also watch out for gaps around internal doors to heated areas and to ventilated rooms such as bathrooms or toilets.
Hardware stores sell a wide range of draught-excluders, weather-strips, caulking compounds and fillers. “Most people can seal the majority of leaks by themselves for very little money,” Mr Brandjes says. He estimates that gap-sealing materials for the average house will cost DIYers about $200.
To get the best results, however, Mr Brandjes suggests hiring professionals, such as Air Barrier Technologies, to test and draught-proof your home. An expert job on a difficult house can cost over $1000, including labour. “Even then, it’s a good investment with a short payback period,” he says.