The construction of two apartment buildings within the ground-breaking Climate Innovation District urban regeneration project in Leeds demonstrates how the EJOT CROSSFIX® substructure 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 creating an entirely new sustainable neighbourhood with high quality urban housing. Over 500 low energy homes with integrated amenities have been created, with a PHPP (Passive House Planning Package) assessed design.
The development’s two apartment buildings, Aire Lofts and District Lofts, feature rear ventilated facades (RVFs) finished with two types of Swisspearl products externally, both with a fibre cement composition. Each is a multi-storey building up to 10 floors in height providing a mix of apartment types.
EJOT CROSSFIX® was chosen for the critically important RVF substructure because it enabled the construction of a highly insulated envelope without compromising aesthetics, with the added benefit of streamlining installation.
How CROSSFIX meets multiple performance goals
The façade of District Lofts was constructed by Hansen Facades using CROSSFIX, in conjunction with main contractor Artium Construction after its successful deployment on Aire Lofts. Here, the system’s versatility and effectiveness were first recognised for attaching secret-fix Ivory panels that demarcate duplex apartments at the ground and first floor levels.
The facade’s EWS1 (External Wall System 1) fire safety rating 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 cavity depth had to accommodate insulation with a 250mm thickness and maintain the required ventilation for a system of this type.
CROSSFIX as a sustainable façade enabler
The CROSSFIX substructure specified 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.
CROSSFIX’s stainless steel composition helped to achieve the façade’s target thermal performance due to its very low thermal conductivity, which minimises the potential for thermal bridging. Coupled with a thermal stop on the CROSSFIX Konsole, this meant that the facade’s U-value is actually lower than it would have been if other substructures had been used with the same thickness of insulation.
Whole life cycle advantages were also provided by CROSSFIX because of its recyclable stainless steel composition, which requires less energy to manufacture compared with metals used in 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 system’s ‘non-flammable’ fire resistance rating 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.
In addition, CROSSFIX does not require special or handed brackets in areas of the façade where space is limited, such as locations between windows and other openings. Versatility of the substructure also means that one subframe can be used for both secret-fix and face-fixed cladding.
Find out more about EJOT CROSSFIX at www.ejot.co.uk/CROSSFIX_Citu_Case_Study.