About Radiant Glass
It is all about Human Thermal Comfort
Indoor swimming pool in winter in highly glazed room
Anyone who has ever sat near a cold window on a winter day or in direct sunlight on a hot day recognizes that windows can cause thermal discomfort.
Thermal comfort is influenced by a combination of physical, physiological and psychological factors. ASHRAE Standard 55 defines thermal comfort as “that state of mind which expresses satisfaction with the thermal environment.”
The two most significant aspects of windows and comfort are the effect of window surface temperature on long-wave radiation heat exchange between the body and the window, and the effect of solar radiation transmitted by the window and absorbed by the body.
Comfort effects of windows are fundamentally different in summer and winter. The winter effect is largely driven by inside window surface temperature, which in turn is tightly correlated with window U-factor and outside temperature.