In terms of heat transfer, both double glazing windows and windows with a vacuum between two panes of glass (known as vacuum glazing) can offer improved thermal insulation compared to single-pane windows. However, vacuum glazing typically provides better insulation and lower heat transfer than double glazing.
Double glazing windows consist of two separate panes of glass with a gap in between, which is usually filled with air or an insulating gas like argon. The trapped air or gas helps to reduce heat transfer through conduction and convection, providing better insulation compared to single-pane windows. However, there can still be some heat transfer through the air or gas-filled gap.
On the other hand, vacuum glazing takes insulation a step further by creating a vacuum-sealed space between two glass panes. By removing the air from the gap, heat transfer through conduction and convection is significantly minimized since there are no molecules present to transfer heat. This results in better thermal insulation and reduced heat transfer compared to double glazing.
The vacuum gap in vacuum glazing acts as an excellent thermal insulator, and it can significantly improve the energy efficiency of a building. However, it's worth noting that vacuum glazing tends to be more expensive and technologically complex to manufacture compared to double glazing.
In summary, if your primary concern is reducing heat transfer, vacuum glazing is generally considered more effective than double glazing due to its superior insulating properties and the absence of air or gas in the gap. However, factors like cost, availability, and specific performance requirements should also be considered when making a decision about window options.