Heating has always been a problem for man, perhaps because the body endures extremes of light and sound without undue discomfort, but against extremes of heat and cold it has no defence. To-day heating engineers are examining not only how to make better heating machines, but also the physical reasons for feeling comfort and discomfort. Experiments have found that comfort is based on four environmental factors—air temperature, radiant temperature, humidity and air movement. These have their effect on the body, which normally manufactures more heat than it requires, storing it to release it at a steady rate later. Comfort, then, depends on controlling this heat loss, and in winter this means making up for the lower temperatures of the surrounding air. It does not necessarily mean altering the air temperature; for so long as heat loss and gain are about equal the body is comfortable. For instance, if we drop the air temperature the body will lose more heat than comfort will allow, and to counteract this we can step up the temperature of the surroundings so that they radiate heat to the body, making up for that loss. To a limited degree an increase in the humidity and a reduction in the movement of the air can bring about the same effect. Humidity, however, in the normal zone of comfort has little effect, and we can disregard air movement, so that we find the most stable form of compensation is by radiant heating. This gives us freedom and flexibility in the other three factors and allows a greater range of activity to be carried out in comfort.

Radiant heating operates on the principle that heat-emission from low-temperature panels gradually warms up the surrounding unheated surfaces, until radiation from the body to the cold walls is reduced to a comfortable level. This does not have the effect of overheating on one side of the body and chilling on the other. From experiment it has also been found that not only is there little temperature variation from floor to ceiling but that there is little or no drying of the air.

A new type of low-temperature electric heating panel, called ‘Medrae’, has recently been introduced into New Zealand, giving the advantages of economy and safety combined with the other qualities of radiant panels. Probably its greatest attraction for architects who are familiar with radiant heating will be the flexibility it gives in heating arrangements.

There are two forms available here at the moment, both similar in appearance to ¼″ sheet of hard-board giving a plain or mottled brown appearance. They are of a laminated construction with the element embedded between the two layers and the electrical connections are so arranged that there is no possibility of shock even when water is spilled over them.

They can be placed in short strips or arranged in the form of a continuous dado installation, or they can be treated as the normal wall or ceiling surface, and where only sufficient are used for heating the rest of the surface can be covered with dummy panels.

Individually they can be placed under desks in the office or for local heating in the bathroom and drying cupboard.

Summary:

• Total cost of installation is relatively low. Reduced running costs due to low current consumption.

• No risk of fire or accidents to children and old people, as the surface temperatures of the panels range from 150 deg. F. to a maximum of 170 deg. F. No chance of shock.

• Gentle radiant warmth giving good comfort conditions.

• No drying of the air and no stuffiness.

• Range of wattages and sizes to suit almost any heating problem.

• Flexible in arrangement with the decoration.

• Can be painted with distemper, stain or leadless paint—care to be taken that lead-base paint is not used, as it has been found unsatisfactory.