HEALTH AND COMFORT

Otago Daily Times, Issue 23672, 2 December 1938, Page 4

HEALTH AND COMFORT

INSULATION IN THE HOME The health and comfort of the family are greatly dependent upon the protection and insulation of the home against the elements. An additional factor, “economy in maintaining the home at a healthful and uniform temEerature during the winter,” also must e given consideration. This is a problem that is common to all mankind, whether he lives in the arctic, temperate, or tropic zone. Insulation, as the term is ordinarily understood, and particularly as applied to dwellings, means protection against heat, cold, sound, and to some extent against fire, or perhaps it should be said protection against the “spreading ” of fire, since there are few, if any, building materials which are actually fireproof. If they cannot literally be burned, they are likely to be 1 so badly damaged by the fire that they are worthless and therefore to all practical intents and purposes destroyed. Insulation against heat or cold means the use in walls and roof of a material or materials that will resist the transference of heat or cold through them, -thus preventing, logically, the entrance into the house of. the extreme heat of summer and preventing as well the escape of the artificial heat which is necessary to make the house habitable during the winter. Economy and comfort are the two outstanding reasons for insulating a home, or any . structure, for that matter. If the walls and roof pf the house are of materials that have a-high thermal conductivity it naturally follows that during the summer the interior of the house will be uncomfortably warm, while during the winter, additional heat must be provided to compensate for the loss.

Insulation Maintains Uniform Comfdrt

During the hot summer months insulation helps to keep rooms, bothxupstairs and down,, comparatively cool and comfortable. During the cold months uniform and comfortable temperatures are obtained at_ the minimum of expense and effort if the house is adequately insulated. In cold climates economy is effected through lowered fuel costs and smaller heating plants. Even with the heating plant functioning at its best, only between 50 and 7b per cent, of the available heat in the fuel is actually transmitted to those parts of the house tf be warmed. Some of the heat escapes through the chimney, and some js lost because of poor firing. Because he can at best only secure threequarters of the available heat (and little over half would be more nearly correct in the majority of cases), the householder should conserve as much heat as possible by seeing that the walls, floors, ceiling, and roof of the house have a high resistance to heat passage. Other things being equal, the house having a high insulation _ value will require less fuel to maintain the same degree of comfort than the house which is poorly insulated. In localities where the winters are long and severe or where fuel is expensive this saving in fuel will be an appreciable amount. Since the amount of heat needed to maintain Comfortable living conditions is reduced, it follows that a smaller heating system will suffice, and so a saving is made on the first cost of the house.

Fire Bisk Reduction

A cold spell leads to unusual demands on the heating system-fires are then given full draught, and furnaces are pushed to the utmost. Unless care is taken, overheating, with its consequent danger of setting fire to the house, may result. In a house having a high insulation value such fire hazard does not exist, since a sudden drop m outside temperature does not effect a correspondingly sudden inside vanatS Testimony as to the importance and practical value of insulation of all kinds—insulation against heat, cold, sound, and the spreading, of Are—is found in the conditions imposed by many of the overseas companies that make large building loans, namely, that structures upon which such loans are made must be built with full insulation of all these kinds. This is stipulated, it is explained, because the long experience of these concerns has taught them that buildings so insulated are more valuable, more easily rented, and’ more readily sold, besides being

more economically maintained and operated than structures not so equipped. The Basis of Insulation The structure of an insulating material must be such that it Is more or less “open ” or “ porous.” Heat, as well as sound, penetrates much more readily a substance which is solid and dense than one in which the encountering of air—that is, dead air (air which is held in place) —creates resistance to the passage of either heat or sound. It follows that a material which is more or less open and which offers such resistance is valuable in confining either heat or sound waves within the area wherein they are contained; this, of course, is the function of insulation, and on this fundamental principle is based all of the insulating materials, of whatever name or structure, which are now upon the market. In the tropics the natives’ huts are made of thick layers of grass, while in Arctic the Eskimo builds his home of many layers of looselypacked snow blocks. In the modern home of civilisation comfort, as well as protection, is made possible through the use of various building products that are now available. In each case protection against heat or cold is obtained through the use of a material that has a structure composed of millions of minute air cells. * The type of construction that is satisfactory for use by the Eskimo and by the savage in the tropics cannot be used in civilised communities, though the insulation value of such construction is very high and efficient. But with modern methods our homes can be; insulated even more efficiently than those of the savage. How Insulation Is Measured

The heat conductivity of a material is a measure of its insulating value; the lower the conductivity, the greater the insulating value. Obviously, the best conductor of heat is the poorest heat insulator.

The thermal conductivity is a property of the material itself, and does not depend upon the size or shape of a particular piece of the material in question. The insulating value of a layer of material of any thickness depends upon the thickness, as well as upon the thermal conductivity of the material of which the layer is composed. In general, the insulating value, that is, the resistance to heat flow, of a flat layer of any kind of material is equal to the thickness of the layer divided by the thermal conductivity of the material. The same principles are involved in what is called “ insulation against cold ” as in “ insulation against heat." The only difference is with regard to the direction of heat flow. The insulation of a house against the outside cold is merely a question of reducing the heat flow from the inside to the- outside. Types of Insulation Materials Modern insulating materials are of two types, which in turn are divided into several classes:— 1. Rigid type, which structurally strengthens the house as well as insulates it. 2. Semi-rigid type, which are added solely for their insulating value. This type is subdivided into several classes, namely, flexible, semi-flexible, and fill insulation. Insulating board belongs in the rigid type, and is the manufactured or processed product of “ wood ” which is composed of millions of minute air cells separated by thin walls of woody fibre. It is this structure which gives insulating board its high insulating value. It was once supposed that the providing of an air space between the inner and the outer walls of a building made sufficient provision for the insulation, but more recent studies have shown that this is not generally true —the air space must provide “dead” air as one most important factor, and another is that numerous small dead air spaces are more efficient than larger ones in which the air can freely circulate.