Sustained support for aluminium glazing systems

Mark Robinson of Sapa Group puts the case for aluminium as one of the most versatile as well as sustainable materials available to specifiers, explaining why the metal is increasingly featuring on the UK’s cutting-edge architectural projects.

‘Chain of custody’ is a term normally used in relation to timber products, by manufacturers seeking to show that their wood comes from ‘well managed forests’ – and to distance themselves from illegal logging and other dubious practices.

Some specifiers might be surprised to learn that there is another material available to them which is arguably even more environmentally-friendly than timber; as well as stronger, more versatile and 100 per cent reusable at the end of a building’s life. Then, rather than being burnt as biomass, it can be reworked in the same manner as newly extracted material.

Aluminium is initially produced from bauxite, one of the planet’s most plentiful resources, and turned into everything from household goods to cars and cladding panels. It is in doors, windows and curtain walling, though, where building designers can access the biggest benefits from aluminium: including squaring the ‘recyclability circle’.

A drop-off in demand from China has meant scrap metal values have eased in recent times, yet nearly all waste aluminium is routinely recovered and reused. In fact it has been forecast that the world could reach the point, within a few decades, where no new bauxite mining is necessary.

Already, where consultants and their clients are targeting the top BREEAM ratings, some aluminium system manufacturers can offer them certification on ingots which comprise 100 per cent recycled metal. Embodied energy is also significantly reduced and at the end of a building’s working life, all of the aluminium will be recovered and the process begun again.

Meanwhile there is no reduction in aluminium’s amazing strength to weight ratio and – unlike PVCu – extrusions do not need to be cloaked with virgin material. Whether anodised or polyester powder coated, aluminium frames offer a very long, low maintenance life as well as strong aesthetics.

Educating the market

The education and student accommodation markets are proving to be very strong sectors at present for those able to provide top-performing aluminium glazing systems, with one recently completed project in Nottingham vividly illustrating the multiple benefits to the solutions available.

Located in the city’s Eastside district, the Discovery Building is part of the University of Nottingham’s BioCity development and has been part funded by the East Midlands Development Agency, working with Nottingham City Council and the D2N2 Local Enterprise Fund, which contributed £6.5m. Willmott Dixon was the main contractor with locally based Bonam and Berry the specialist fabricator, supplying and installing the fenestration package.

Apart from its scale, the four-storey bioscience building is prominent because of the sculpture across the main facade whose aluminium tubes carry fibre-optic lights controlled by NASA measurements of solar activity. Forming the backdrop to this, Sapa’s NRGY 62 system had to be engineered to take the large loads created by long spans and very heavy, acoustic glazing units.

Project architect for CPMG, Matt Greenhalgh, commented: “The system proved very adaptable while Bonam and Berry were proactive in coming up with ideas to realise our aspirations for the glazing. Because of the wide, large format units and the heavy glass, the system provided extra structural support or diagonal bracing; while for the glass-to- glass junctions at high level, Bonam and Berry used a special rod to tie the transoms together, which provides a very attractive, bespoke finish.”

The main area of glazed facade is 45 metres long and 15 metres high, within which NRGY 62 fixed lights measure up 4,000 mm x 1,500 mm tall. The 34 mm thick Saint-Gobain solar control glazing, supplied by System 3, delivers a centre pane U-value of 1.0 W/m²K, meaning the system can perform to Passivhaus standards.

During the early stages of the project, one of Sapa’s facade specialists worked alongside Bonam and Berry’s designers to help devise a solution to how the very high loads from the centre of the transom could be transferred back to the mullions. Consequently, bespoke 45 degree brackets were manufactured, which were bolted back to the system members, all concealed within the spandrel area.

Whether fulfilling the aesthetic design aspirations for different developments or matching the most challenging environmental and performance standards, aluminium systems are proving themselves capable of keeping up with the pace of change.

Mark Robinson is technical director at Sapa, part of the Sapa Group