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Nestled in the vibrant community of Greenwich, South London, The Underwood has been designed to provide much-needed social housing to the borough. As part of the Royal Borough of Greenwich’s commitment to cutting carbon emissions from its housing stock, the homes were developed to achieve net zero operational emissions whilst also being affordable to heat and operate. This has been achieved through a fabric-first specification utilising the TEK Building System to form the shell walls and roof for the homes.
LOCATIONLondon, UK
ArchitectFuse Architects
With a ‘fabric-first’ approach for delivering the Royal Borough of Greenwich’s net zero operational carbon goals, the TEK Building System was specified for the walls and roof of the building.
Designed by Fuse Architects, this set of terraced houses comprises seven two-bedroom residences, along with a fully wheelchair-adapted three-bedroom house.
Kingspan TEK Delivery Partners, Glosford SIPs, collaborated with the architect and main contractors from an early stage in the project development. They oversaw the design of the SIPs shell, helping to achieve the modern aesthetic with minimal structural steels to limit embodied carbon. Mechanical ventilation heat recovery (MVHR) systems were fitted, providing effective ventilation within the airtight homes, along with a range of low carbon technologies such as air source heat pumps and photovoltaic (PV) panels.
Offsite solution
The TEK Building System is formed from structural insulated panels (SIPs) which comprise a high-performance rigid insulation core sandwiched between two layers of oriented strand board type 3 (OBS/3).
This insulated panel design provides a key building block for project teams adopting a fabric first approach. For The Underwood, a further 70 mm of Thermawall TW55 was specified as an external liner for the wall panels, allowing the external walls to achieve an outstanding U-value of just 0.11 W/m2K.
The panels feature a proprietary jointing system which ensures excellent insulation continuity across the building envelope, limiting thermal bridges. In combination with the OSB/3 facing, the panels also support highly airtight constructions. This was a key priority for the project with the design calling for an air permeability rate of 3 m3/h.m2 @ 50Pa to further limit heat losses and energy demand.
An MVHR system was then specified to ensure excellent air quality within the completed homes. This system uses the heat from outgoing stale air to warm incoming fresh air, further limiting the heating demand for the homes.
Design, Fabrication & Delivery
Glosford SIPs developed the architectural designs into CAD plans for the panelised construction. The Royal Borough’s commitment to minimise the embodied carbon impact of the homes presented some additional challenges as George Gifford, Commercial Director at Glosford SIPs, explained:
“In order to minimise the embodied carbon impact of the homes, we could only use structural steels as an absolute last resort. Our team worked to create an engineering solution that only required a single steel beam on the whole project which was required for a ceiling mounted hoist system. All other structural beams were engineered timber.”
Once the designs were agreed, Glosford SIPs cut the panels to the required dimensions using a CNC router– ensuring the finished panels precisely matched those within the designs. This included openings for windows and doors which were pre-cut to the project’s specific dimensions. This factory-controlled process ensured minimal site waste and allowing accurate scheduling – a key consideration given site space restraints as George went on to explain:
“The project’s location in central London and the relatively tight nature of the site presented some additional challenges as space was limited for material assembly, storage requirements, and siting the crane. This meant the installation period was slightly longer than we are used to although the entire 8 units were erected by Glosford in under 7 weeks to a weathertight state.”
The fast-track erection process for the weathertight building shell is possible due to the panelised construction of the TEK panels. Sole plates were secured to the floor slab. The ground level TEK panels could then be simply slotted onto these and fixed together. Glosford SIPs ensured the panel kits were pre-coded to match the CAD designs – providing a clear installation process for the site team.
Once the shell of the homes were erected, a 70 mm thickness of Thermawall TW55 was then fitted to the outer face of the wall panels. With a thermal conductivity of 0.022 W/mK, the rigid insulation boards allowed the walls to achieve the ambitious U-value of 0.11 W/m2K with a slim overall construction. The outer façade was then completed with a brick façade with dark grey slate effect tiles applied to the roof.
The completed homes provide comfortable spaces which are affordable for tenants to heat and have net zero operational emissions.
Dave Hughes, Design Director from Fuse Architects, discussed the scheme:
“This project demonstrates how the delivery of net zero operational carbon houses does not need to be overly complicated, expensive or time consuming. By using TEK we were able to achieve excellent fabric performance and airtightness with a rapid build programme and limited additional cost above a baseline Building Regulations compliant scheme and a traditional delivery method.”
NB: All images courtesy of Fuse Architects
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