I am looking for a material that can be used in a non commercial environment that will allow all (or nearly all) light to penetrate but will be heat resistant (By heat resistant I mean it will not allow the heat to penetrate to the other side, not that the materiel itself won't get hot - although they may be dependent on each other).
To better understand my requirements, I am trying to illuminate a room with 40,000 lux of light using a few metal halide (MH) bulbs, for a scientific experiment. The bulbs will consume 1800 - 2400 watt which means it will produce a lot of heat. Since real people will partake in the experiment (sitting about 6-12 inches from the light source in order to increase the amount of lux reaching the subject) I am concerned the heat produced by the bulbs will be too difficult to bear. Therefore, I want to place some material (such as a glass or plastic) in between the subject and the light source so maximum light penetrates with minimum heat.
What is the best way to do this?