How Efficient is Vacuum Double Glazing?
Vacuum glass achieves exceptional levels of energy efficiency. The earliest vacuum insulated units reached U-values of approximately 1.10W/m2K (identical to modern double glazing), but modern vacuum insulated glass can achieve U-values as low as 0.48W/m2K.
Here are some typical comparisons of glass types and U-values to give context:
- Single glazing U-value 4.8 to 5.8 W/(m²K).
- Double glazing U-value 1.2 to 3.7 W/(m²K).
- Triple glazing U-value 0.7 to 1.0 W/(m²K).
- Vacuum glazing U-value 0.48 to 1.1 W/(m²K).
What are U-values?
A U-value is the number that will tell you how much heat and energy a window will let through and you can gain a better idea of how the glazing will perform. U-Values are a measurement of a material’s insulation efficiency, and the lower the number, the better the energy efficiency is.
U-values are measured in watts per square metre per kelvin (W/(m²K)). For example, a double-glazed window with a U-value of 2.8, for every degree difference in temperature between the inside and outside of the window, 2.8 watts will be transmitted every square metre. The lower the U-value, the better insulated the product is.
What are the applications for Vacuum glazing?
A vacuum cavity is super-efficient and therefore can be much thinner than a conventional double-glazed unit (over 50 times thinner) while delivering a better U-value. This means that in the UK market, vacuum glazing has typically been used to replace single glazing in old window refurbishment. When we first came across vacuum glazing in 2014, we immediately knew that it was also an excellent option for new Heritage window manufacture. The market was full of new windows with poor quality 10-12mm thick glazing units which didn’t deliver on performance, longevity or traditional aesthetic. Vacuum glazing ticked all the boxes and we set about designing a full range of windows and doors to revolutionise the Heritage window and door market.