Building regulations Building regulations for new homes set down the standards quite rigorously. Floors require a U Value of 0.25, walls need a U Value of no more than 0.27, the figure is 0.2 for a pitched roof and 0.16 for attic space. Practically, this means that floors require 60mm of heavy-duty foilbacked polyiso foam board (the sort manufactured by Kingspan or Xtratherm), with 60mm required in the walls.

Attics, on the other hand, will require either two layers of 150mm fibreglass or similar insulating material (it was one layer under the older regulations), or 100 mm of polyiso insulation over the rafters and 38mm under.

But insulation is a relatively new phenomenon, and building regulations did not apply when many of the houses in Ireland were built. So while your second-hand property may have either period charm or old-style quaintness, the reality is that you will probably have quite a job when it comes to retro-fitting your insulation.

And while the new building regulations will not apply for a retrofit, architects have been advised to implement at least the older regulations, which require less material, but which are still quite strict.

Adhering to standards when retrofitting insulation may not seem to be so important now, especially given the numbers of residential properties that have little or no insulation. But it will become more of an issue with the introduction of the Energy Performance of Buildings directive, which will require every home to have an energy rating if it is undergoing a commercial transaction (selling, letting, etc). The directive will impact on all houses, old or new, by 2009, and a bad energy rating could lead to a lower price for your property.

Floor insulation So what can you do if your house is not properly insulated? There are three areas that may need consideration, but, of all of these, the floor is the one which will be least likely to be insulated. Bare floorboards in an old house could be a real source of heat-loss, although thanks to the principles of physics, most convection loss will happen through the roof.

This is good news, considering that most people don't bother with retrofitting floor insulation . . . the job is a major structural one, and involves considerable upheaval.

External walls Most of the heat-loss in an older house occurs through the external walls and the roof. External walls are responsible for most of this heat-loss (over 50%), while the roof is generally responsible for about 25% of heatloss (this may seem low, but only a portion is heat is lost through convection . . . radiation, and to a lesser extent, conduction, are a significant drain on heat resources).

While most insulating materials will be suitable (except in the case of cavity walls), the most popular means of insulating a wall in an older house is to use a product such as Kingspan or Xtratherm.

Essentially, these are products which comprises of plasterboard with attached synthetic insulation . . . and is fixed directly to the wall. This is an effective means of insulating, and is a preferred method, thanks to the ease of installation. But, for extra protection, it is better to fix batons to the wall before attaching plasterboard, thereby utilising nature's own means of insulation . . . empty space. The trouble is that this involves much more work, especially if windows and radiators are involved.

Attic insulation But while retro-insulating the floor and the walls will involve some sort of construction work, the attic is a part of the house which should never be ignored . . . and it can be done quickly and easily.

The most popular insulating material is still glass fibre, which offers excellent thermal protection, but is messy and occasionally dangerous, when people come into contact with it, or when it starts to break down.

Rock wool is another material which is often used. The trouble with rock wool is not only that it tends to be about twice the price as glass fibre, but it is also more commonly associated with sound insulation, with less emphasis on its thermal qualities.

Natural insulation One trend which is coming to the fore in this age of environmental awareness is the use of natural products. Chief among these is sheep's wool. The insulating qualities of wool have been known by sheep for millennia, and have long been appreciated by people.

Still, we have been strangely reluctant to use wool as an insulating material in our houses, despite the fact that Australians and New Zealanders are well aware of its qualities, and Mongolians have used sheep's wool to line their yurts for hundreds of years.

"Most insulation products are rated to last between 25 and 30 years, " says John Byrne of Ochre Wool, an Irish company that offers a number of insulating products, including wool. "Wool has a lifespan of at full performance of 50 years, and when it starts to break down, it has none of the hazardous dust associated with other forms of insulation."

One of the main advantages of wool is the fact that it can perform well even when damp . . . it is this quality that allows sheep to keep warm in winter and cool in summer.

Wool works by trapping air and moisture, and is an active form of insulation which both warms and dries.

Of course, some people might be put off by the fact that their insulation is coming from an animal, but the reality is that wool insulation is as clean as any other. "Our wool is changed from a greasy fleece into building- grade material, " says David Pierce of Sheep Wool Insulation, an Irish company providing wool insulation. "It is scoured down to its core fibres, treated with insecticide, and all fibres are combed in the same direction. It is a hygroscopic material with low thermal conductivity, and therefore a high insulating factor."

Other natural materials which are being used as insulation include wood fibre products, recycled newspapers and even hemp-based fibres. And better insulation can also be achieved by fitting lagging jackets on boilers, double glazing and fitting heat reflective panels behind radiators.