The Dominion Post
What works, and what doesn’t
Should you bubble wrap your windows, or hang blankets behind your curtains? Is it best to heat one room or the whole house? Joanna Davis finds out.
What really keeps your home warm and dry? We put some well-worn ideas about what does and doesn’t work to the experts at EECA, the Energy Efficiency and Conservation Authority.
Insulation a top priority
Estimates of the amount of heat lost through the roof, floor and windows of your home vary, but average out around 40 per cent, 20 per cent and 25 per cent respectively.
Marcos Pelenur, EECA’s group manager of strategy, insights and regulations, says the figures depend on the construction of the house, and the insulation already in place.
Underfloor and roof insulation are top priorities. ‘‘Wall insulation is also effective,’’ Pelenur said, ‘‘but because you need to remove the wall lining, it’s best to think about it when and if you’re renovating.’’
It is worth putting in more, or better, insulation than is required by the Building Code ‘‘if you can afford it’’.
Do we really need to retro-fit double-glazed windows?
Pelenur says double glazing is undeniably effective. If you don’t want to replace all your windows, consider doing it piecemeal, one or two at a time. ‘‘Think about installing double glazing in the rooms your household uses the most, or where there’s condensation,’’ he says.
As a homemade hack, he says sticking bubble wrap to the glass does work, ‘‘but it may not be attractive for everybody’’.
A better low-cost solution could be to buy a window film insulation kit from a DIY store.
‘‘It’s a transparent film that you tape on and shrink wrap, and it creates another layer. It’s as inexpensive as $30 for one or two windows.’’
Optimise your curtains
‘‘Curtains are an easy thing you can do to help keep heat in,’’ Pelenur says. ‘‘Don’t forget you should open them when the sun is shining.’’
He recommends thicker curtains, especially double-layered with a thick lining. Curtains that touch the floor, are wider than the window frames and that fit tightly against the wall are all helpful.
‘‘Where you’re going to lose your heat is thermal bridging – when different materials touch each other. The window will transfer the heat from inside your home to the outside. If curtains are in contact with the window, it’s worse.’’ He does not recommend blankets as a low-cost lining solution. Instead buy cheap lined curtains from curtain banks.
Heat the whole house or just the living area?
‘‘It’s an absolute priority that people’s homes should be warm and healthy, but you can do that using the rooms you use the most,’’ says Pelenur.
A basic timer allows for heating a bedroom shortly before you go into it, for example. He does not recommend leaving heat pumps on a low setting 24/7.
‘‘If you want to avoid a budget blowout, you should set the heat pump just before you get home and switch off when you don’t need it. Set the thermostat between 18 and 21 degrees Celsius to combat damp and cold. Above 21C, it gets more expensive to heat.’’
It’s also important to clean the heat pump filter regularly, before winter sets in and then every three months.
Pelenur recommends those on low incomes check their eligibility for grants of up to 90 per cent on heating and home insulation through the Warmer Kiwi Homes programme.
Good/bad advice for a warm, dry home
■ Door snakes are basic but effective, and are especially worth putting alongside exterior doors.
■ Improve the seal around cat flaps with silicone sealant or rubber insulation tape.
■ Do not leave the oven door open as it cools. This is a safety risk, and the heat will escape eventually anyway, so it does not make a difference.
■ Do not use unflued gas heaters indoors. The fumes are dangerous, and they create about one litre of water vapour an hour.
■ Do not dry laundry indoors – a load of washing is thought to release up to five litres of water into the home.