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Principle of insulating glass
- Apr 09, 2018 -

Hollow glass due to the internal dryer can be adsorbed water molecules exist, gas is dry, the temperature falls, the interior of the hollow glass also won't produce any condensation phenomenon, at the same time, in the outer surface of the hollow glass dewpoint will also rise. Such as outdoor wind speed of 5 m/s, indoor temperature is 20 ℃, relative humidity was 60%, 5 mm glass when outdoor temperature is 8 ℃ began condensation, and 16 mm (5 + 6 + 5) hollow glass under the same conditions, the outdoor temperature was minus 2 ℃ when the condensation, 27 mm (5 + 6 + 5 + 6 + 5) three layer hollow glass in the outdoor temperature of 11 ℃ before condensation.

There are three ways of energy transfer of insulating glass: radiation transmission, convection and conduction.

Radiative transfer

Radiation is the transmission of energy through radiation in the form of radiation, including visible, infrared and ultraviolet radiation, just like the transmission of the sun's rays. The reasonable configuration of the insulating glass and the reasonable thickness of the insulating glass can reduce the energy loss by minimizing the transmission of energy through the radiation form.


Convection is caused by the temperature difference between the two sides of the glass, causing the air to fall on the cold side and rising on the hot side, causing the convection of the air and causing the loss of energy. Cause there are several reasons for this phenomenon: one is the glass and the framework of the perimeter of the sealed, cause both within and outside the window frame swapping can directly produce gas convection, leading to loss of energy; The second is the interior of the hollow glass space structure design is unreasonable, resulting in the effect of temperature difference of the inside of the hollow glass gas to produce convection, drive of the exchange of energy to produce energy loss; 3 it is to constitute the window of the whole system of the internal and external temperature difference is bigger, the hollow glass is the difference in temperature between inside and outside is bigger also, cold air with the aid of the role of radiation and heat conduction, first of all, on both sides of the hollow glass to produce convection, and then through the hollow glass transfer in the past, the whole forming a loss of energy. Reasonable hollow glass design can reduce the convection of gas, thereby reducing the convection loss of energy.

The conduction transfer

Is the conduction transfer driven by molecular motion object, the energy of movement, and achieve the purpose of passing, like a wok for a meal and use electric welding, and hollow glass conduction of energy transfer is accomplished through the glass and its internal air. We know that the thermal conductivity of glass is 0.77W/ mk. And air coefficient of thermal conductivity is 0.028 W/mk, thus, the thermal conductivity of glass is the air 27 times, and the presence of reactive molecules such as water molecules in the air, affecting hollow glass energy conduction and convection transfer performance, the main factors and thus improve the sealing performance of hollow glass, is an important factor to improve the performance of hollow glass heat insulation.