Sustainable, efficient and aesthetic

The construction of two apartment buildings within the ground-breaking Climate Innovation District urban regeneration project in Leeds demonstrates how the EJOT CROSSFIX® system can be used to incorporate rainscreen facades into highly sustainable buildings, without the need to vastly increase insulation depth.

Developed by Citu in partnership with one of Scandinavia’s leading architectural practices, White Arkitekter, and civil and structural engineers Civic, the Climate Innovation District is not only boosting the supply of high quality urban housing, but actually creating an entire new sustainable neighbourhood. Over 500 low energy homes with integrated amenities have been created, with a design that has been PHPP (Passive House Planning Package) assessed. The development’s two apartment buildings, known as volumes, are constructed using a steel structure with composite metal deck floors and a light gauge steel framing system. This facilitates a RVF featuring two types of Swisspearl products externally, both with a fibre cement composition. Each volume, named Aire Lofts and District Lofts, takes the form of a multi-storey residential building up to 10 floors in height, providing various types of apartments. EJOT CROSSFIX® was selected to provide the critically important substructure because it enabled the construction of a highly insulated façade without compromising aesthetics, with the added benefit of streamlining installation.
 

How CROSSFIX® meets multiple performance goals

The entire façade of District Lofts was constructed by Hansen Facades using CROSSFIX®, in conjunction with main contractor Artium Construction. It was chosen following its successful deployment on Aire Lofts, where the system’s versatility and effectiveness were first recognised by Citu after it was used for secret-fix panels used to demark the duplex apartments at the ground and first floor levels.

The EWS1 (External Wall System 1) fire safety rating for the facades had to be balanced with thermal and ventilation goals. Given the high thermal requirements, designed to a weighted U Value (based on a typical subframe arrangement) of 0.13 W/m²k, the substructure cavity had to be sufficiently deep to accommodate insulation with a thickness of 250mm and maintain the required ventilation for a system of this type.

CROSSFIX® as a sustainable façade enabler

The specified CROSSFIX® substructure consisted of a 220mm Konsole K1 in A2 stainless steel, complete with the Powerkey for enhanced structural stability in the same metal grade, which supported L, Z and T profiles. The EJOT package was completed with five types of stainless steel fasteners to provide secure assembly with consistent performance. The stainless steel composition of CROSSFIX® made an important contribution to meeting the thermal performance goals for the facades. As this type of metal has very low thermal conductivity, it minimises the potential for thermal bridging. Coupled with a thermal stop incorporated into the CROSSFIX® Konsole, this meant that the facade’s U-value is actually lower than it would have been if other types of substructures had been used with the same thickness of insulation.

In addition, considering the whole life cycle of the products used to form the facades, CROSSFIX® is mainly formed of recyclable stainless steel which requires significantly less energy to manufacture compared with many other RVF substructure systems – confirmed by an Environmental Product Declaration (EPD).
 

A smart solution for modern construction methods

The multiple sustainability benefits provided by CROSSFIX®, enhanced further through the ‘non-flammable’ fire resistance rating of the system and a unique design flexibility that enables it to be used in both horizontal and vertical assembly, means it is well-aligned with the higher efficiency, safety and quality targets demanded in modern construction.

Valuable efficiency benefits were delivered on-site because CROSSFIX® does not require any type of special or handed brackets in areas of the façade where space is limited, such as in locations between windows and other openings. In addition, the versatility of the substructure meant that one subframe system could be used for both the secret-fix and face-fixed cladding.