Metal offers a sustainable future

The Metal Cladding and Roofing Manufacturers Association (MCRMA) explains how metal building envelope systems contribute significantly to the sustainable design concept, thanks to its high recycled content, recyclability and energy efficiency.

The Government has announced the end of the UK’s zero carbon buildings policy and that it does not intend to proceed with the zero carbon Allowable Solutions carbon offsetting scheme. This means that the 2016 zero carbon homes target is being dropped, as is the 2019 target for non-domestic zero carbon buildings. It also means that there will be no further changes to Part L in any form before 2016.

However, the UK will still be required to deliver nearly zero carbon buildings from 2021 (and 2019 in the public sector) and to meet the nearly zero carbon target, non-domestic buildings will need to be designed and built to be as sustainable as possible and to contribute as little as possible to carbon emissions.

For many years specifiers have chosen metal over other materials for its energy efficiency, low maintenance and durability. However, metal has other attributes, namely its striking beauty, clean appearance and versatility; metal cladding systems offer a choice of steel or aluminium substrate, which can be linked with a range of colours, shapes, panel sizes, finishes, profiles and vertical and horizontal applications. These attributes have established metal as the material of choice for both new and refurbishment construction.

Steel and aluminium offer a better life cycle return on investment than other materials. Today’s metal construction products are protected by highly durable paints and coatings that now ensure a service life in excess of 40 years.

Metal construction is efficient and competitive; buildings can be rapidly constructed using metal-based primary and secondary components that are efficiently manufactured off-site and therefore are dimensionally accurate and of known quality. In order to create truly sustainable buildings, it is critical that project teams take a holistic approach. The building envelope should be considered in a much broader context such as sourcing of materials, durability and longevity of building envelope systems, integration of renewable energy technologies and end of life options. Specifying products that have been certified to an internationally recognised framework, such as BES 6001, will help the design team to validate the ‘green’ credentials that companies claim. Adopting this approach will lead to a well-integrated, high performance design – bringing potential cost savings and added efficiencies that are far greater than they would be if building elements were considered individually.

Both steel and aluminium can be reused or recycled repeatedly without losing their qualities as building materials. The recovery infrastructure for metal recycling is highly developed and highly efficient, and has been in place for decades. Current recovery rates from demolition sites in the UK are 99 per cent for structural steelwork and 94 per cent for all metal construction products – figures that far exceed those for any other construction material.

When metal is specified for a building, it is unlikely to become waste. Steel and aluminium always have a value and are only ever sent to landfill as a last resort. Waste generation is one of the least sustainable aspects of construction; choosing a metal-framed and clad building incorporating highly efficient insulation is the simplest and most effective way to reduce waste. Even during manufacture and fabrication, any swarf or offcuts are recovered and recycled back through the primary production process.

Changes to Building Regulations will result in more renewables being installed on both new and refurbishment projects. MCRMA members are at the forefront of developing innovative metal roofing solutions such as photovoltaics (PVs) and transpired solar collectors (TSCs) which will contribute to achieving the nearly zero carbon target. Examples include the integration of solar PV systems with existing and new roof assemblies, enabling buildings to generate their own electricity; and the development of perforated TSCs to deliver naturally warmed fresh air into the building. MCRMA members have developed functional coated steel products based on renewable energy for use in the roofs and walls of buildings.

Delivering low-energy buildings with excellent in-use energy performance is a challenge. MCRMA members understand the factors that can affect the performance gap (the gap between the designed and expected and actual energy performance in the built environment) and how this can be minimised to
achieve maximum as built performance. It is important to recognise that the ‘pick and mix’ approach to projects where non compatible systems and components may be brought together by some contractors can easily negate the benefits of an energy efficient design. Whilst the installer may be tempted by the cheaper option, the ultimate responsibility for meeting the performance specification should remain with the designer and the client. Working with a main contractor and manufacturer who understands the risks and the value of a specification should not be underestimated.

The best assurance of compliance to meet sustainability targets is to source systems and products from reputable manufacturers who can demonstrate the pedigree of the materials used and support design requirements with job specific data. We should also be mindful that even a well-designed building system will fail to comply with the regulations if it has not been properly installed by trained, experienced and supervised contractors.

Manufacturers are best placed to offer advice about their particular products and MCRMA member companies can advise on the suitability and performance of their materials, systems and assemblies for specific applications. Additional project specific advice may also be obtained from one of the independent roofing and cladding inspectors featured on the MCRMA web site at