As a major part of the structure of the building, the design and specification of the façade can make a significant difference to the embodied and operational carbon. However, there several important steps that can be taken to minimise the impact.

Recycled and recyclable materials

To create a sustainable design, it is important to consider the whole lifecycle of a material – including to what degree it can be recycled at the end of its life and how much energy will be used to repurpose it. Also, choosing products that themselves are made from recycled materials is an important consideration. This will help minimise waste, reduce the demand for ‘primary’ materials and decrease the embodied carbon of the system and therefore, the building.

From this perspective aluminium has several key advantages. It is endlessly recyclable with no degradation in quality. It is also easy to separate from other waste so at the end of the building’s lifespan, a large proportion of the aluminium components can be recovered and recycled.

In addition, melting down recovered aluminium for reuse requires only 5% of the energy needed for primary aluminium production. This means that products made of recycled aluminium have a much smaller carbon footprint.

At TECHNAL, an increasing number of our door, window and curtain walling products across our portfolio are manufactured using Hydro CIRCAL® 75R aluminium. This high-quality aluminium contains a minimum of 75% recycled end-of-life aluminium (post-consumer scrap), from the likes of façades and windows that have been removed from buildings. As a result, it has one of the smallest CO2 footprints of any aluminium worldwide with 2.3 kg of CO2 emissions per kilo of aluminium. This is 86% or 7 times less than the global average for primary extraction.

Sustainable design

Another important part of improving the sustainability of the building is to reduce the energy it requires when in use. Taking a ‘fabric first’ approach is central to this, and increasingly a focus of building designs in every sector. Optimising the performance of the systems and products that make up the building fabric can reduce the amount of heating, cooling and lighting that is required. The right specification of systems for the façade, including doors, windows and curtain walling, can minimise thermal bridging and maximise air-tightness as well as helping to exploit natural light while preventing overheating.

Façade elements that have been engineered for excellent thermal performance will include high-levels of insulation and thermal breaks in the construction to prevent heat loss. For example, the modern and slimline design of our C160 and C160S doors includes glass fibre reinforced polyamide strips that reduce thermal conduction, with the option to add thermal inserts to improve the performance further. As a result, the C160S can achieve a U value for the frame (Uf) as low as 1.40 W/m²K.

However, when selecting products and systems it is important to ensure they will perform as designed in practice, as ‘performance gaps’ can seriously impact the operational emissions of a building over its lifespan. Therefore, architects should ensure that any products specified have been thoroughly tested. At TECHNAL, we have invested in state of the art testing facilities to provide the necessary test data as well as project specific support for more complex requirements.

In addition, by working with a system specialist, the design can be optimised to provide the best possible levels of natural light without impacting the comfort of the building occupants. This may require solar shading elements to be designed and positioned in such a way that it shades certain elevations of the building from the peak summer sun without blocking daylight from the lower angle winter sun.

Sustainability in practice: Institute for Advanced Automotive Propulsion Systems

At the University of Bath’s Institute for Advanced Automotive Propulsion Systems (IAAPS), our curtain wall solutions were used to help achieve a sustainable and energy efficient building. The new, world-class automotive propulsion research facility in Bristol was constructed to achieve a BREEAM Very Good standard. The facility will support global automotive industries to deliver future generations of advanced propulsion systems and ultra-low emission vehicles.

The impressive front elevation façade features TECHNAL curtain wall manufactured using Hydro CIRCAL® 75R recycled aluminium. The façade also had to achieve a high level of performance with low heat gains through the façade. Saint Gobain COOL-LITE SKN 154 solar control glass was selected to deliver a low G Factor (0.28) and help control the amount of heat that penetrates into the building. The floor to ceiling glass was also important in achieving an even distribution of light entering from the north to reduce the need for artificial light during the daytime and reduce the overall building energy consumption.