The insulation principle of insulating glass
Insulating glass is a glass product in which two or more pieces of glass are evenly separated by effective supports and bonded around the edges with sealant, creating a dry gas space (usually air or inert gas) between the glass layers.
Its heat preservation effect mainly comes from three aspects:
Gas insulation (the most important
The gas filled inside the hollow layer is the key to insulation. Whether it is dry air or more commonly used inert gases (such as Argon), their thermal conductivity is much lower than that of ordinary air.
A low thermal conductivity means that heat is difficult to be conducted through the gas, effectively blocking the heat exchange between the indoor and outdoor.
Reduce convection
The hollow layer is a sealed space where gases cannot flow freely like outdoor air. This greatly reduces the heat transfer caused by air convection.
Increase thermal resistance
Insulating glass is equivalent to increasing the total thickness of the glass and the air layer within it, creating more obstacles for heat transfer. Its overall thermal resistance is significantly higher than that of single-pane glass.
How to measure the insulation effect of insulating glass?
We usually measure the thermal insulation performance of glass by the U value (or heat transfer coefficient).
The lower the U value, the better the insulation performance (the more difficult it is for heat to escape through the glass).
The U value of ordinary single-layer glass is very high, approximately 5.0 W/m²·K, and its heat insulation effect is very poor.
The U value of standard insulating glass (5+12A+5, that is, two 5mm glass pieces with a 12mm air layer in between) can be reduced to about 2.8W /m²·K, and its thermal insulation performance is nearly twice that of single-pane glass.
If Low-E glass is used and argon gas is filled, the U value can even be reduced to below 1.5, achieving an excellent insulation effect.
The "insulation" of insulating glass is bidirectional
In winter: Prevent the warm heat inside the room from escaping through the Windows to the cold outside, keep the room warm and save heating costs.
In summer: Prevent the high-temperature heat from outside from entering the air-conditioned room through the Windows to keep the room cool and save on cooling costs.
Therefore, a more accurate term for its "heat preservation" is "heat insulation", that is, to prevent heat transfer, regardless of whether the heat direction is from the inside out or from the outside in.
Conclusion
Insulating glass has an extremely excellent thermal insulation effect and is the preferred configuration for energy-saving doors and Windows in buildings. If your home is undergoing renovation or having its Windows replaced, and you are in pursuit of better indoor comfort and lower air conditioning energy consumption, choosing insulating glass is definitely the right decision.
For the best results, it can be considered to upgrade to:
Low-E insulating glass: A low-emissivity film is coated on the glass, which can reflect infrared thermal radiation and significantly enhance the insulation performance.
Argon gas filling: Replacing ordinary dry air with argon gas, which has a lower thermal conductivity, further enhances the insulation performance by approximately 10%.
Increase the thickness of the hollow layer: Within a reasonable range (usually 12-20mm), the thicker the hollow layer, the better the insulation effect.
