Know how thermal insulation glazing can benefit facilities managers

Featured Article
11 Apr 2019

As Featured in Facilitate Magazine - 03/19

Phil Brown, European regulatory marketing manager at Pilkington United Kingdom Limited, part of the NSG Group, explains thermal-insulation glass and how it can benefit facilities managers. 

Interestingly, more than 25% of the heat from most buildings escapes through the windows – 90% of this through the glass itself. 

This points to a clear area where facilities managers can recommend improvements to keep the buildings they manage warm while minimising energy costs and emissions; a recurrent challenge for many.

You may think the solution is as simple as installing double-glazing, however we’ve come a long way since standard double-glazing was at the forefront of thermal performance. Advanced, thermally-insulated glazing solutions are now available, which offer facilities managers a cost-effective way to make the buildings they manage warmer and more energy-efficient.

How does thermal insulation glazing work? 

To understand how thermal insulation glass units keep the heat in, it’s important to look at exactly how losses are measured. 

The amount of heat lost through a window is determined by its U-value. 

U-values are expressed as W/m2K, referring to the amount of energy that will pass through 1 metre squared of a material for each degree of temperature difference from one side to another. In this context, this is the amount of heat that passes through glass when it’s colder outside than in. So, the lower the number, the better.

Low-emissivity (low-e) glass has far lower U-values than traditional glazing, thanks to a near-invisible coating that is usually applied to the inner pane of a double glazing unit (surface 3, counting from the outside).

A low-e coating works by reflecting warmth back into internal spaces while still letting in heat from the sun. This increases the effect known as ‘passive solar gain’ which essentially allows buildings to be heated for free by sunlight, especially during the colder months.

Thermal insulation is typically provided by double-glazing units containing one pane of low-e glass, with an inert gas such as argon (which has a much lower thermal conductivity than air), in the cavity. It is possible to achieve even higher levels of thermal insulation by specifying double glazing with a low-e coating on both surfaces 2 and 4. These advanced units can achieve a U-value as low as 0.9W/m2K, which was previously only achievable with triple-glazing. 

Triple glazing units, with two panes of low-e glass and appropriate cavity widths, can achieve U-values as low as 0.5 W/m2K. However, this may not always be the best choice for all applications, as there are other important factors to consider. Not only does the additional glass pane make triple-glazing more expensive, it can also require larger, heavier frames than double-glazing. This in turn makes it challenging to specify in certain projects or retro-fit into older properties. Given these barriers, advanced double-glazed units can often be the optimum solution. 

An alternative solution, particularly for heritage and listed buildings, is vacuum insulating glass technology – using a vacuum rather than air or argon between the two panes – which continues to grow in popularity since we brought the world’s first commercially-available vacuum glazing, Pilkington Spacia™, to market. Vacuum insulating glass allows the thermal performance of a traditional double glazing unit to be achieved in an ultra-thin format, which can even fit into single-glazed frames.  

This is particularly useful to FMs looking after heritage or conservation buildings, where double-glazing is often not an option due to the building’s original window frames having been designed for single-glazed windows.

How facilities managers can create a more sustainable future

The potential for improvement in glazing – and therefore, in both thermal insulation and energy-efficiency – is huge. 97% of the buildings in Europe are considered ‘inefficient’ according to Building Performance Institute Europe (BPIE), mostly because of using single or outdated double-glazing. This is an obvious area where facilities managers can recommend improvements when it next comes to renovations. 

As government regulations on energy-efficiency in buildings continue to tighten, thermal insulation glass can help facilities managers ensure the properties they manage remain compliant while cutting costs and ensuring a warmer, brighter future for all.