When sunshine penetrates the glazing on a building it can heat up the inside of the premises to such a point that it causes discomfort to the staff.

This situation occured on TBS Ltd's new book distribution centre at Frating, Essex. To overcome the problem, the company had Madico Duralux 500 window film, type SG340X-K Neutral Grey, applied to the outer face of the glass. Duralux 500 films reject solar heat through a combination of reflecting and absorbing the sun's rays and hence reduced the eat gain at Frating to an acceptable level.

Duralux 500 films have a special finish made of Kynar® polyvinylidene fluoride (PVDF), which is a long-lasting exterior coating suitable for use on the external surface of double glazed units. Using it on the outside ensures that unwanted heat is deflected back into the atmosphere before it actually gets to the glass. This means that the glass is not subjected to high levels of heat gain that could occurif the film were installed on the inside, and therefore reduces the risk of the glass in sealed double glazed units cracking as a result of thermal stress.

"The building was constructed without air conditioning," said Sandra Marvin of TBS Ltd, "and as a result got very hot during the summer. As soon as the film had been installed we noticed a drop in temperature. It acheived our objective of reducing the effects of sunlight without cutting out any natural light."