The hidden culprits around the house sending your winter heating bills soaring

Here they come again, those icy fingers of winter that – unless you’ve been a diligent eco-fundamentalist and very effectively insulated your house against heat-in and heat-out issues – you’re bound to feel sneaking in through any gap in your home’s thermal envelope.

You’ll feel it in the deep south, in the mountains, in the inland on those chilly and starry winter nights, and even in southern Queensland for those few cool weeks of July and August when a breezy Queenslander design works the wrong way. If you haven’t got a heater pumping, you’ll be dreaming of a log fire.

If you’re in a draught-porous house that, as energy efficiency consultant Richard Keech says, “acts like a leaky bucket”, you’ll also feel it in your hip pocket.

Sustainability Victoria says heat loss, which can affect a majority of houses, can push your winter energy bills up by 25 per cent.

And, it gets worse. For every degree you set your heating thermostat above 18-20 degrees, the energy costs rise by 10 per cent.

Yet, says Keech, who has conducted 500 energy efficiency assessments on Victorian homes in the past five years, the motivation for people to review their home’s “24/7 uncontrolled ventilation issues” – draughts – is motivated more by their comfort level than it is about reducing costs.

“They find they’re just not warm enough. And when people can’t stay warm or cool enough, it really focuses the mind,” he says.

There are the obvious heat leaks: draughts under doors and the poorly insulated walls, floors and ceilings. “I could go on forever,” says the engineer who has a masters degree in environmental energy efficiency.

But there can also be many unexpected holes in your home’s thermal envelope. Keech lists downlights, extractor fans, wide-mouth chimneys and poorly-sealed door frames and window architraves.

“Even in a well-insulated house the thermal performance will be dominated by the worst performing bit,” he says.

“(Older) downlights can be surprisingly problematic as they’re often designed to let air pass through them. They also leave a hole in the insulation. Some houses have dozens of these lights, and it’s like having a bloody big hole in the ceiling.”

Keech says simply replacing bulbs is not recommended because although it does improve lighting efficiency, it’s a lost opportunity to improve other problems. “You need to replace the entire fitting with one of the new sealed LED fittings that are not that much more expensive.”

A similar cumulatively significant cause of heat loss can be all but invisible to the untrained eye. But when he sees a tell-tale line of dust along a window sill or door frame, “it’s a sign of a persistent draught”.

When Keech looks above a window or door jamb, which most home-owners would probably never consider inspecting, he often discovers gaps.

“Typically, they can be enough to put a credit card into. But some are big enough to put a finger into,” he says. “This is sloppy building work, and if they’re in all rooms, in aggregate, they can add up to metres of leaks. Architraves need to be properly sealed.”

Beneath a door, a permanently affixed draught stopper that can be as little as $7 at your local big box hardware outlet, or by adding a sticky strip around the whole door jamb, “are not the best ways to seal a door because they disregard the fact that most doors are warped, typically at the top and the bottom”.

Exhaust fans that aren’t spinning can also “let air pass through easily, which is another big hole. You can either replace them or cover them with a backdraught protector”.

Old style chimneys that aren’t in operation are a huge problem but are another of what Keech calls “the low hanging fruit” of his “weak link analysis” of poorly-performing houses, because they too are generally affordable to seal up.
“We do that by carving a block of foam rubber that can be used to plug the chimney, but that is also removable.”

Counterintuitively, perhaps, the author of the chattily informative blog New Energy Thinking and a book, The Energy Freedom Home, Keech says it’s the vintage homes that may start with the worst problems but that have greater scope for improvement “because they were better built”.

“A lot of newer homes have problems that are harder to fix because they have more downlights and often have no eaves.”