Even with modern advances in the glazing industry, large installations of glass are relatively poor thermal insulators when compared to insulated walls.
As heat escapes through the glass at a faster rate than through any nearby walls, an area of lower temperature can be felt in the air nearby. This can be particularly problematic where comfort in all areas of a space are required.
Most notably in restaurants, but other use-cases include
Kitchen Extensions (bi folding / sliding doors)
Rooflights – See below for more on the cold drop effect.
Rooflights are particularly susceptible to developing large areas of cooler air beneath them. When this air becomes cool enough, it sinks through the surrounding warmer air, creating the “cold drop” effect as illustrated below. This can make an environment less comfortable, potentially making people turn heating up a few degrees to compensate
Eliminating chills with heated glass is done with minimal power usage. Just 50W/m2 is enough to raise the glass temperature enough to prevent heat being drawn from the surrounding air, ensuring the most comfortable environment possible.