Wrap your house up - from top to bottom - and watch your heating bills plummet

HOME IMPROVEMENTMany houses are poorly insulated but retro-fitting is a viable option

"WE HAVE the worst housing stock in Europe," Dr Eddie O'Connor told Pat Kenny on his radio show last week. "It looks nice but it's jerry-built."

O'Connor, who set up wind energy company Airtricity, which was sold last month for €1.9 billion, went on to advise listeners that "the best way to spend your money is to insulate your house. We should celebrate it, there should be awards for it," he said, warming to his insulation theme.

It is sensible advice but many homeowners will find it hard to act on because ideally good insulation with heat values that exceed (our basic) Building Regulations should be fitted when the house is built. When retro- fitting it is best to start from the top.

ATTIC

Up to 20 per cent of heat lost from a home escapes through the roof and effective attic insulation can pay for itself within two to three years.

During an energy audit last year I found out that my own attic - which looked well-insulated - only had 60mm of fibreglass insulation between the joists when Building Regulations suggest that at least 250mm is required. Sustainable energy expert Aodhan MacPhaidin recommends 300mm.

If the attic is not used as a room, insulation goes on the attic "floor" between the joists. The main choices are rolls of mineral wool (DIY friendly), and blown in mineral wool insulation and cellulose fibre (not a DIY job). With rolls, simply roll it out between the joists, to the same level as the joists. Wires should always be above the insulation. Good sources are DIY superstores such as B&Q, Atlantic Homecare and Homebase as they have a range of insulation types to take home that day, or local smaller DIY shops which are usually prepared to order in.

Different methods of insulation are required where the attic is a room, and this should be discussed with your builder (and needs to comply with Building Regulations 2002, Part L Conservation of Fuel and Energy).

WALLS

According to Sustainable Energy Ireland (SEI), most houses built before about 1980 have no wall insulation. Many houses built during the 1980s have some wall insulation. Houses built since the 1991 Building Regulations came into effect are required to have wall insulation. Eddie O'Connor's "Jerry-built" description starts to ring true as it's clear that there are hundreds and thousands of homes with virtually no insulation.

As much as one quarter of the heat lost from a house can escape through the walls and properly insulating walls can reduce this by two-thirds. The way to go depends on the type of wall. If it is solid concrete or built from cavity blocks, the best choice would be to insulate internally. Internal insulation or "drylining" involves having a frame built on the existing wall, packed with insulation of at least 60mm, which is then covered with board and plastered.

External insulation is another option. In this case the insulation is applied to the external walls and it's rare in this country because it involves specialist companies and is relatively expensive.

Sustainable Energy Ireland suggests it could cost upwards of €15,000 for a typical semi-D.

If the wall is a cavity-wall, ie, has a gap between an outer and inner leaf, then the standard method of insulation is to have foam or beaded foam insulation pumped into the cavity. The Irish Agrément Board (www.nsai.ie) has a list of certified products and installers on its website.

FLOORS

Up to 15 per cent of your total heat loss could be disappearing through the floors. A thick carpet with foam backing should help. A bigger, but worthwhile, job would be to put insulation between the joists of suspended timber floors - a job most will only consider if the floorboards are going to be up anyway as it a filthy, tricky job.

While the business of even coming to grips with U values and thermal conductivities is too daunting for most homeowners, there is considerable free, basic help available. Sustainable Energy Ireland has an excellent website (www.sei.ie) and a booklet on insulation, as well as an advice hotline, tel: 023 42193.