Sunshine control

Press, 29 April 1981, Page 11

Sunshine control

Solar control glass or film allows maximum benefit from an attractive view and from natural light without incurring the disadvantages associated with sunshine pouring in through large windows.

Reflective glass or film deflects the sun’s rays, protecting those inside the room from most of the solar heat and eliminating both glare and fade-causing ultra-violet light.

The mirror effect on the outside gives daytime privacy to those within and the images on the outer surface 'can be consciously used in the building’s design.

The mirror effect of reflective glass is the main design feature of the new container terminal administration building at Port Chalmers. A four-storey, sound-proofed and tempera-ture-insulated structure in glass, it is virtually invisible. What one sees are the images on its surface. , There is double glazing throughout and none of the windows opens to the out-

side. Glazing of the whole facade required 950 square metres of 6mm “Reflectafloat,” with an 80mm air gap between the two layers for sound proofing and heat insulation.

The temperature indoors is iregulated and fresh air brought in by means of a heat exchange system that keeps the interior cool in Isummer and warm in winter.

After dark, privacy from the outside is lost but artificial light within is reflected inwards, improving illumination.

The advantage of film is that it can be applied on site to existing windows without mess or disruption, and if the glass is broken, the pieces cling to the tough polyester film.

Reflective film can be applied to clear sheet or polished plate glass but not to heavily-figured glass.

The darker reflective film can reduce solar heat gain by about 75 per cent, while the less heavily- metalled film can reduce heat gain by about 50 per cent.

The lighter film does not give such a highly-mirrored finish, so is more transparent .from the outside. ‘ Solar radiation becomes 'heat when it is absorbed by 'the substance it strikes. This is experienced when you sit in the sun on a cold day and become over-hot — and dazzled, although it is cold out *of the sun. • Where this- occurs it is usually best to reduce the effect of the sun with reflective film and provide gentle, background heat.

In rooms where direct sunlight is enjoyable, but the damage to furniture, drapes and carpet is worrisome, non-reflective or even clear film is probably the answer. This lets through considerably more light and heat than the reflective kind but filters- out almost all the damaging ultra violet rays.

It is also suitable where the only problem is glare from a water or patio surface. Both reflective and nonreflective film is available in several colour tints with a range of filtering effects. Like sunglasses, some even improve visibility under bright conditions.

Reflective film, and nonreflective to a lesser degree, is said. to insulate glass against heat transmission, with the result that not only does less heat pass in .through* closed windows in the summer, but also more interior heat stays inside in winter.