Climate Measurements for Glass with Different Energy Properties

Recent developments in glass treatment techniques have made it possible to improve vehicle compartment climate considerably. At the same time, it has become obvious that traditional temperature measurements do not cover the total need for describing climate properties. This is due to the fact that human heat balance, which is the fundamental process behind feeling cold or hot, is a function not only of temperature but also of draft and radiation. Coating glass is one means of preventing solar radiation from coming into the compartment. In doing so, the solar heat load through the glazing can be reduced by some 50 %. This, of course, gives a lower compartment temperature in parking conditions and also a faster cool-down in hot climate. It has two major secondary impacts on the human being:

• At a given air flow through the compartment, the necessary inlet temperature is increased, thereby causing less draft.
• Direct radiation on body surfaces is also reduced.

The total evaluation of glass with reflecting or absorbing properties must therefore include measurements with instruments like the Bruel & Kjaer comfort meter or the Voltman system as presented in SAE reports nos. 850042 and 890049. The latter system, which gives a total picture of heat load on different body parts in a given situation, is of course the most sophisticated method for this part of the evaluation.

In this paper, some suggestions are given for testing routines. They include:

• parking heat-up and idling cool-down tests.
• Voltman on-road testing and simulated on-road testing outdoors.