Solar radiation energy of 97% centered at a wavelength in the range of 0.3-2.5um, this part of the energy from the outdoor; long wave radiation energy below 100 DEG C objects are concentrated in 2.5um above, this part of the energy is mainly from the interior.

If the room is bounded words, winter or in high latitude area we hope radiation energy in outdoorand indoor radiation energy, do not leak. If the wavelength of the radiation as the boundary of words, indoor and outdoor radiation boundary point is at the wavelength of 2.5um. Therefore,the choice of a certain function of the chamber window becomes a key.

Ordinary transparent 3mm thick glass of solar radiation with 87% transmittance, daytimeradiation energy from outside but most through; but the night or cloudy and rainy weather, from indoor objects radiation energy absorbed by the 89%, so that the glass temperature, and thenthrough the dissemination of its heat to the interior and external radiation and convectionexchange. It is impossible to effectively prevent indoor heat to the outside vent.

Solar radiation Low-E hollow glass of 0.3-2.5um has a transmittance of more than 60%, the dayfrom the outdoor radiation energy can be most through, but the night and rainy weather, heatradiation from the interior of the object about 50% above by the indoor heat radiation is reflected back, only less than 15% of the absorbed by the by then after radiation and convectionexchange loss it can effectively prevent the indoor heat to the outside vent. This characteristic of Low-E glass, which has control one-way flow of outdoor heat effect.