Energy-efficient homes:Insulation involves more than double glazing. Do it properly and you could end up with a boiler-free 'passive house', reports Michael Kelly
What will we do once fossil fuels become too scarce, and therefore too expensive, to use for keeping our homes warm? Here's one possibility: What if your house could be so well designed, built and insulated that it didn't require oil - or gas, coal, logs, woodchip or biomass - to heat it?
This is not some Utopian dream: such dwellings are called passive houses, and they use daylight and the heat that we and our household appliances generate to maintain a comfortable temperature. The expertise and technology to build them already exist. Ten have been built in Ireland so far, and some forward-thinking local authorities have started incorporating elements of passive-house design into social-housing schemes (see right). Lars Pettersson, who runs the Galway-based Scandinavian Homes, explains: "There is a consistent temperature of 20 degrees in the house, and because the building is so well sealed it just doesn't lose heat."
It seems most of us are so obsessed with comparing the price of different fuels that it never occurs to us that our homes could be snug without any heating system. Duncan Stewart, who presents the RTÉ series Eco Eye, believes we have been getting our priorities wrong. "We all tend to think about this in terms of switching from oil to renewable. But the first step is to make our buildings leaner. Then we can decide on what fuel we need, albeit with smaller energy requirements," he says. "The critical thing is that we reduce the energy demands of houses to a quarter or fifth of what they are currently."
In that context, it seems silly to allow houses to be built that don't meet the passive-house standard. And yet, apart from some notable exceptions, we do just that: 80,000 of them a year. "There is just no excuse with new builds," says Stewart. "All these new homes are going to have to be upgraded, and the costs of upgrading are 10 times higher than doing it at build."
Jeff Colley, editor of Construct Ireland, a resource for sustainable building and renewable technologies, believes the Government's much-vaunted - and oversubscribed - grant scheme, with its focus on alternative-fuel appliances, feeds into the idea that the problem will be solved by finding a viable alternative to oil.
"The focus should be on setting highly efficient standards in construction and ensuring they are maintained. The vast majority of Irish homes don't even meet current standards. There was an energy-performance survey carried out where they surveyed 52 houses and only one passed."
If we can't build a passive house, we can consider retrofitting our existing homes, to make it leaner. Stewart says: "It's simply a case of looking at the envelope of your house, which basically is the roof, walls, floors, windows and doors, and deciding on the most cost-effective methods of preventing heat loss." One of the best is to deploy more attic insulation. "Twenty-five per cent of the heat loss in a house happens through the attic. It's one of the simplest measures you can take and it has incredible payback. You should have at least 12 to 14 inches of good-quality insulation, and the access hatch should be draught-sealed and insulated also."
Floors and walls are more complex. "Timber floors can be taken up so that a breathing membrane can go down, which will stop draughts, and insulation can be laid between the joists. With walls you can look at one of three things. You can inject insulation into them, which works in some cases but not all; you can dry-line the inside of the house, which obviously has space implications; or you can look at external insulation."
The glass in windows and doors is another big culprit in heat loss, so argon-filled triple glazing is the new benchmark. We should also try to minimise the number of north-facing windows. Colley encourages people to go to suppliers that specialise in low-energy windows. "You need to be dealing with suppliers who know about the glazing but also the best way to incorporate the window into the house."
If you find all this a bit daunting, help is at hand. "Energy auditors will be more commonplace from next year, and they will help people find weaknesses in their homes," says Stewart. "If you have a group of identical houses, then people could get together to fund an audit, as the same principles will apply for all the houses. That is a great starting point." mkelly@irish-times.ie.
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LEADING THE WAY
The Baile Glás development (below) in Lombardstown, Co Cork, shows how low-energy design can be incorporated into social and affordable housing - a crucial step, given that people who qualify for social housing tend to be most at risk from rising fuel prices.
The housing, which has been designed by MCO Architecture for Cork County Council and Blackwater Resource Development, is expected to use 60 per cent less energy than standard houses, even though each home costs only 9.5 per cent more to build.
Every house faces south, to benefit from the sun's heat, and has a glass-walled "winter garden", or enclosed terrace; a heat-recovery system takes warm air from it to run the heating and hot-water systems.
The kitchen and living areas are in the warm centre of the house; rooms that need less heat, such as bedrooms and storerooms, are on the northern side, where glazing is minimised. To help conserve heat, all of the windows, which are double-glazed, contain argon.
Local authorities have a key role in creating energy-efficient housing. Fingal, Dún Laoghaire- Rathdown and Wicklow county councils all now require developers to build homes with low energy and carbon-dioxide emissions - a cause, like the Baile Glás scheme, for optimism.