Vacuum insulated glazing is similar to double-glazing, except that it doesn’t have a gas in the cavity, it has a vacuum instead.  The vacuum makes a far more effective insulated window than any gas could, and therefore only requires a small cavity. There is no need to have a big, thick unit as with a double-glazed unit and therefore, vacuum glazing can deliver exceptional thermal performance whilst retaining a very slim glazing profile (as slim as single glazing).

It is aptly named insulated glass for good reason! In fact, creating a vacuum between two panes of glass can be up to eight times more efficient than single glazing and 5% more efficient than triple glazing. Furthermore, vacuum glazing offers greater performance in terms of acoustics or sound reduction, higher light transmission and increased solar gain compared to single, double and triple glazed units.

Let’s take a look at the construction of single glazed and double-glazed windows to aid our understanding of how vacuum glazing differs:

Single glazed windows

Before double-glazing came on the scene, windows were manufactured with only a single glass pane. Many older, period properties and listed properties still house single glazing, and it is the main reason these older style buildings can feel draughty and chilly. In fact, a single glazed home can see as much as 60% of its heat inside escape through the windows alone, which is why your home will stay far mor effectively when double glazing is installed. On top of all that, single glazing provides less insulation against noise and is less effective at preventing condensation.

Double-glazed windows

A typical double glazed window unit consists of two sheets of glass with a 16mm gap between the two. Double glazing works by filling the air space between the two panes with Argon (an inert gas that provides superior thermal performance – it also helps reduce sound). The two glass layers and argon filled gap, means that thermal energy is unable to move as freely through the windows as it does across single glazing. Single glazing sees heat escape by transfer through air, through the glass, and by radiating from the glass, but with double glazing, thermal energy must move through two panes of glass plus the argon filled space. The argon gap is too small to allow for proper conduction and the argon itself slows down the movement of heat energy.

Where is vacuum Insulated glass best applied?

All our expert joiners at Parsons Joinery are approved installers of Fineo vacuum insulated glass. Fineo is one of the most popular options for listed buildings and conservation areas because it is a premium glazing option that not only delivers better thermal efficiency and sound insulation than triple glazing but is as slim as single glazing. Therefore, it can be easily retrofitted into the existing box frames of listed buildings enabling the property to retain most of its existing features and originality.

Comparing Fineo with traditional glazing:


We have not had a planning authority refuse this glazing option yet. The benefits associated with vacuum insulated glazing such as Fineo are unrivalled. In fact, Fineo vacuum-insulated glass boasts a U-value of just 0.7 (A++ standard).

Our confidence in this innovative glazing solution is reflected in the long-term warranty of 15 years that we have assigned against it. Our team here at Parsons Joinery are very skilled at finding a solution that works for both the customer and the planning officer, so if you need some help deciphering a glazing option that works for you, we would be delighted to chat with you. 01273 814870.