The main problem with the car climate while running is thermal asymmetry on the human body. This asymmetry is caused by solar radiation, drafts from cold air and drafts due to radiation from cold surfaces.
During winter, the cold surfaces of the side windows are a major source of discomfort, not only because of the above-mentioned cold radiation towards the outer upper body parts, but also as a result of the air stream needed for demisting the windows. This air stream has a very low temperature when reaching the B-pillar, where it easily deflects, hitting the driver's/passenger's shoulder.
In order to avoid these problems, tests have been carried out with side-lights consisting of two hermetically sealed panes with a small air space in between. It was found that the surface temperature is significantly raised, by some 15°C, at low ambient temperatures. Not only are the heat losses reduced, but mist formation is also prevented. Negative aspects are weight and cost. For future development, chemically tempered glass might create possibilities for lighter solutions.