Blog 7

Selecting the right Glass Facade Specification

One of the benefits of a ‘whole building’ approach to energy efficiency is the ability to compensate for poorer performing areas or elements by ‘beefing up’ others. There are limits to that, so a level of common sense is necessary. Building regulations stipulate best-case U-values for new buildings, so a maximum level of performance must be achieved.

For work to existing buildings, area-weighted U-values combine the performance of building elements. This approach allows for larger areas of glazing to be incorporated in an extension, with surrounding elements improved to compensate.

Specifying lower building U-values is all very well, but there is a point at which they become economically and practically infeasible. The addition of more and more insulation generates diminishing returns, so really low U-values require a thickness of construction that may not have been planned for.

As it is with insulation, so too with Stick & Unitized Curtain Wall – including Point Fixed Glazing Systems. Manufacturers are always looking to improve the performance of their products, and current technology can produce Frameless Slim Glass Facade with whole-unit U-values of around 0.80 W/m2K.

Eventually, maybe all Glass Façade Systems, and glazing generally, will offer U-values this low – or even lower – but for now, specifiers, installers, and clients need to be aware of what is appropriate to their project.

Quoting a certain U-value for a Minimalist Glass Facade as a performance specification, and then expecting a contractor to source a window of the correct size that meets the specification, risks compromising the compliance calculations if they don’t know where to look for one. Product substitution is a risk inherent in all construction projects. It could be for reasons of cost or availability, or because those supplying or purchasing the materials do not understand the implications of differences in performance. Uninformed or unauthorized specification changes are a consistent cause of design intent not being achieved.

Where Architectural Structural Glazing Products are concerned, widespread understanding of U-value declarations is not what it could be. If that leads to mistaken performance claims and the installation of Glass Facade that do not match the original specification, then compliance simply may not be achieved.

When Glazing Systems meets the needs of a Construction Project, every effort should be made to stick with the choice. Unlike other building materials, glass is difficult to simply swap to a like-for-like alternative that costs less or is more readily available. If in doubt, contact the Doors & Window Manufacturer for advice.

Better still, specify the right quality products from a reliable manufacturer at the tender stage and set a tone for the project where quality and the end result is prioritized over short-term gains.