Insulation Gives Winter Warmth, Summer Coolness

Press, Volume CVIII, Issue 31657, 18 April 1968, Page 24

Insulation Gives Winter Warmth, Summer Coolness

A home that is comfortably warm in winter and pleasantly cool in summer is every house-owner’s objective and one that is not easy to obtain. But some thought given to insulation during construction can go a long way toward producing the desired result. Every home-owner spends a lot of money in a year on fuel to

counter the seasonal variations in climate—whether it be solid fuel burnt in an open fireplace or grate, electricity or gas to supply heaters of various types, or oil for space or- central heating. In all cases the object is to warm the air in a particular room or throughout the whole house and avoid the necessity of keeping the body warm with extra and weighty clothes. Unquestionably it

would be money well spent if all the heat paid for was retained. But warm air rises (or is it displaced by the colder air around it?) and unless it is prevented, a large proportion escapes from the particular room or house through the ceilings, floors, walls, doors and windows. So much of the cost of heating a home is a dead loss because much of the air so wanned cannot be retained. Modern homes are

notoriously cold homes. They have, compared with the mansions of the nineteenth century, thin walls and large areas of glass. Many are cold and draughty. Research has shown, it is claimed, that 15 per cent of the warm air that escapes from a modern house does so through the floors, 20 per cent through the windows, 25 per cent through external walls and 40 per

cent through the ceilings and roofs. Fortunately, not all the warm air gets away but it has been calculated that about 60 per cent does so. As a result fuel bills can be about 60 per cent higher than they need if that desirable warm air can be retained inside the home.

Obviously, it would be sound business to spend a proportion of the capital cost of heating systems and of the fuel bills to prevent heat loss. Which is where insulation comes in. What is insulation ? It is a term used to describe materials of various forms which present a barrier to heat movement—which in other words keep the warm air inside a house in cold weather and outside it in the summer.

The experts agree that “still-air” is the best insulation known—but the most difficult to achieve in practice.

One method used in commercial buildings is to have double windows with the air between them sealed so that it cannot escape. But it is costly, too costly, for the average home, and does not help with the warm air that gets away through those walls, ceilings and doors. But insulating materials that retard heat losses to a marked extent have been developed and are being increasingly used in commercial buildings and homes. They are not cheap, but what is today? And it has been proved beyond reasonable argument that the capital outlay is materially compensated for by savings in fuel bills. Where to insulate? Obviously the most worthwhile results will be obtained by insulating the ceilings which, tests have shown, allow 60 per cent of heat to elude the home-owner. Wall and floor insula-

tion also pays dividends, leaving only windows and doors as the main source of escape for that warm air.

A popular insulation material for both ceilings and wells is fibreglass, made from glass fibres so microscopic that it takes 625 fibres to make up a cubic inch. The material looks and feels like crisp cotton wool. It has low thermal conductivity and is noncombustible, an important consideration in a wooden house.

Fibreglass for wail and ceiling insulation comes in flexible rolls or in various sizes of batts which can be fitted into the cavity between studs. Or it can be obtained as fibreglass “wool” which can be simply poured over the ceiling between the joists.

Also widely used for ceiling and wall insulation is a wood pulp material called insulflut, a light and fluffy sub-

stance with marked fireretarding and soundinsulating characteristics. Applied professionally it is usually sprayed over the ceiling to a depth of four inches.

Expanded polystyrene is another insulating material for ceilings and walls. So is insulbestos, a lightweight cellulose fibre that has been chemically fireproofed. It can be blown on to a polythene film stapled to the timber membeis,

professional operators using a portable electric motor and petrol engine unit that sprays the material where it is wanted through a flexible hose. If preferred, the material can be poured between the ceiling joists from polythene bags supplied in a useful handyman pack.

Another material used for house insulation is perlite, a volcanic silica mined in the Rotorua - Taupo

area. It looks like sand but is only one-twelfth of its weight.

Mixed with cement it makes a concrete that floats on water. At perlite concrete floor provides more insulation than 20 inches of ordinary concrete.

The product can be used in ceilings by laying sealed plastic bags between the joists and a perlite and gypsum plaster board is made for wall insulation.

Widely used in home and commercial building insulation are laminated aluminium foil materials that reflect heat. Sheets of this material have great strength and toughness, permitting them to be tacked over ceiling joists or'over rafters just below the tiles,