Jon Palethorpe, commercial director at Sapa Building Systems, examines the growing trend for using aluminium curtain walling systems and explains why they’ve become integral to contemporary architectural design .
Creating beautiful and striking buildings that are also innovative and push boundaries is a constant challenge as architects strive to find new ways to achieve design excellence. Add to this the increasing importance being placed on energy efficiency and sustainability, and there is a difficult balance to be struck.
Design potential
According to the Council for Aluminium in Building (CAB), around 25 per cent of the world’s aluminium is used in building and construction and its popularity as a building material continues to increase. Aluminium is incredibly versatile; unlike most other metals, it can be economically extruded into almost any shape to exact tolerances and therefore meet unique structural and aesthetic requirements, providing architects with endless design potential.
In the last ten years, some of the UK’s most iconic commercial buildings and premium office spaces have been created using aluminium glazing systems, such as Sir Norman Foster’s ‘Gherkin’ building and Renzo Piano’s Shard. These buildings have paved the way for ever more complex facade solutions such as the new Co-operative Group head office building in Manchester, designed by 3D Reid, which features an intricate glazed double-skin facade made from an aluminium unitised curtain wall system.
With colour anodizing and powder-coating, aluminium also provides the broadest range of finishes when compared to other materials.
Another key benefit of aluminium glazing is that it is avail- able in the broadest range of finishes, compared to PVCu for example, and it can be coloured with architects and designers currently favouring grey powder coated and ‘terracotta’ finishes.
Building benefits
There are notably just two ‘types’ of curtain wall systems – stick and unitised – but they are providing architects with a vast range of options. Architectural commentators suggest that facade contractors and system companies have typically focused on the delivery of low rise curtain wall projects integrated with door and window systems. These systems themselves allow for ‘added’ options such as solar shading or photovoltaic panels.
Yet in recent years, the use of unitised curtain walling has gained momentum and although its primary use has been in ‘statement’ building in London and other UK cities, it is now much more widely available, with various types of projects able to benefit from its prefabricated approach.
Whereas stick systems are traditionally installed on site, unitised systems are made up of completed units which are hung onto the building structure. These have a number of advantages including the speed at which they are installed, which helps keep cost down and the use of scaffolding rather than cranes. This helps alleviate any problems with sites that are difficult to access such as airports, railways or congested city centre locations. Unitised systems are also constructed off site, allowing for greater quality control and minimising risk.
Although it was pioneered in a Liverpool housing project in 1978, the use of double-skin cavity facades is now becoming popular in big commercial buildings such as the Gherkin or new Co-operative HQ in Manchester, largely driven by the need for greater energy efficiency. This innovative type of system allows air to flow in the cavity between the two skins, creating a natural source of heating and ventilation and improving a building’s environmental credentials. In cool climates the solar gain within the cavity may be circulated to the occupied space to offset heating requirements, while in hot climates the cavity may be vented out of the building to mitigate solar gain and decrease the cooling load.
Sustainability
With the Government aiming to reduce the UK’s carbon emissions by at least 80 per cent on 1990 levels by 2050, it’s little wonder that energy efficiency and sustainability are all now serious considerations for any new building.
As a sustainable building material, aluminium is fully recyclable and renowned for its ‘cradle to cradle’ life cycle. In fact 75 per cent of all the aluminium ever produced is still in circulation and the recycling process itself only requires about 5 per cent of the energy that was consumed in the production of primary aluminium.
Facades of the future
As architects continue to balance building design with green credentials, the use of aluminium as a building material can provide many of the answers. What’s exciting is the way in which architects are exploiting its versatility, which both feeds, and is fed by, the technical innovations of the world’s leading aluminium system designers.