Sustainability defined

With increasing pressure to specify building systems offering clearly defined sustainability, Andrew Cross of Kestrel Aluminium Systems gives his thoughts on the use of aluminium as a key building component

In construction terms, aluminium is considered to be a ‘permanent’ material as, unlike some other metals, it loses none of its inherent properties as a consequence of repeated recycling. The World Green Building Council has set a target to make all buildings ‘zero carbon’ by 2050 so, with demands to reduce carbon emissions and the environmental impact of production processes, use of materials which embody recycling as
an inherent feature are becoming increasingly significant.

Aluminium is now used across a wide range of sectors and, as a matter of interest, is still very much the most valuable item in our recycling collection. From an emissions perspective, use of pre and post-use aluminium greatly reduces energy consumption and adds tangible value to the economics of production. To put this into perspective, it saves around 95 per cent of the energy consumed in the ‘primary’ production process.

For those specifying metal window and door systems there is, therefore, a clear incentive to use a raw material that can be reused on an infinite basis. In terms of enabling building designs to achieve the highest level of BREEAM certification, aluminium can also provide tangible benefits in terms of assessment of an asset’s environmental, social and economic sustainability through use of standards developed by BRE. In addition, it enhances specific aspects of technical performance such as thermal, acoustic and energy efficiency.

Use of natural materials, timber in particular, undoubtedly has its supporters, but most natural materials offer limited potential for recycling. Deforestation, dwindling resources and a generally adverse effect on the environment can only become a bigger issue as demand for greater sustainability increases. By contrast, aluminium products made using recycled material present consistently low environmental impact while offering strength, durability, stability and greatly reduced weight compared to steel. Among the many other benefits they have to offer, natural corrosion and UV resistance enable the specifier to forecast with considerable accuracy the cost of maintenance over a system’s design life.

While there has long been an economic incentive to recycle aluminium, there is now greater organisation in the construction industry in terms of post-use collection, evaluation and sorting. The CAB (Council for Aluminium in Building) is now actively promoting use of higher grades of aluminium scrap while seeking the active involvement of all members of the supply chain in the management of material re-use. One of the aims of its Closed Loop Recycling Scheme is to formalise sorting of scrap into specific wrought alloy groups. Until the scheme was introduced any such grading had been voluntary, but the initiative reflects a widespread chain of thought that a requirement will ultimately be placed on architects to specify ‘embodied carbon’ content. This means main contractors will need to provide clearly demonstrable evidence of sustainability in all aspects of their supply chain.

To achieve greater efficiency in terms of thermal transmittance, high performance fenestration design is becoming increasingly sophisticated. Aluminium can be formed into complex and diverse profile shapes, a feature which makes it ideal for contemporary designs. From a manufacturer’s perspective, working alongside specifiers offers considerable benefits in terms of product development.

This is being seen across the construction spectrum and is highlighted, for example, in the modular construction of affordable homes such as the prototype two-bedroom detached ‘modpod’ in Hockley. Commissioned by Birmingham City Council, it was built offsite and craned into place, in this case in little more than an hour. Critical features of its design include 60 mm casement windows designed by Kestrel Aluminium, to provide a high standard of airtightness using low U-value glazing units. They not only provide high performance and aesthetic value, but are designed to be easily broken down into their component parts when the need for replacement arises.

Among aluminium window and door manufacturers, those which stand out
are achieving differentiation by demonstrating a combination of discernible sustainability and an intent to improve their eco-performance. The material’s ‘permanence’ and its undoubted flexibility and versatility will pave the way for products of increasing environmental value. If we add to this the widely accepted ecological argument against use of PVCu and tangible evidence provided by aluminium window and door systems with a design life which has already spanned several decades the case for its use has never been stronger.

Andrew Cross is marketing manager of Kestrel Aluminium Systems