Bunhill Energy Centre
Manufacture & Installation
Turning Underground Heat into Civic Architecture
The Bunhill 2 Energy Centre transforms waste heat from the London Underground into a public asset, providing sustainable warmth to more than 500 homes, two leisure centres and a local school in Islington. Located on City Road among a cluster of new residential towers, the building occupies a pivotal urban site, with five visible elevations and no rear façade, it needed to serve both as a working energy plant and as an architectural statement of civic innovation; The design brief called for a structure that expressed technical purpose without visual heaviness, a building that could contribute positively to the urban realm while embodying London’s shift towards low-carbon infrastructure. Cullinan Studio’s concept fused engineering performance with sculptural form, the plant’s flues and extraction towers were integrated into a singular geometric volume, a visible marker of environmental transition that celebrates the unseen networks beneath the city.
Realising the Vision
Early design discussions proposed natural copper cladding for its warmth and material honesty, however the humid exhaust from the heat exchange system presented a risk of uneven patination and rapid verdigris formation, We collaborated with the design and client teams to identify an alternative, anodised aluminium finished in AnoCopper04 was chosed delivering the copper tone with greater stability, precision and sustainability. Aluminium’s lightness and rigidity allowed the panels to be fabricated from 3mm sheet, achieving perfectly flat surfaces even with large perforated zones, the anodised layer, 25 microns thick to BS standard, ensures a 40-year finish warranty and a 80-year design life, meeting Islington Council’s longevity targets for public infrastructure. A brushed surface finish was introduced to animate the façade under changing light conditions, we proposed Novelis’ SSL BF (Stainless Steel Look Brushed Finish), a calendered embossed texture rather than an abraded brush, the subtle shift in method prevents micro-scratches and surface dulling while creating a vibrant, directionally reflective sheen resulting in a dynamic façade that reflects the sky and surrounding structures in soft motion, avoiding the glare and distortion of mirror-polished metal. Together, these decisions established a calm, crafted exterior, technically sophisticated but visually effortless, the anodic colour generated through light diffraction rather than pigment absorption, gives the surface a living quality, shifting tone with daylight and weather.
Fabrication & Installation
We engineered and fabricated the 625m² façade as a coordinated system of perforated, solid and expanded aluminium components across the elevations, cluster-punched perforations create a ventilated envelope that manages heat and air flow, the perforation density increases with height, achieving three effects, improved free-air circulation for the plant, reduced climb ability at street level, and a perceptual lightness that helps the building dissolve into the skyline. At the base, cast aluminium panels designed in collaboration with artist Toby Paterson introduce a tactile civic layer, while the mid-levels feature CNC V-grooved diamond panels, a detail developed by NES to translate the architect’s graphic intent into an achievable fabrication method. Expanded mesh panels were formed from 1050-grade anodising aluminium, selected for its ductility and visual compatibility with our brushed NES AnoCopper04 finish. Installation was managed by Colloid Engineering using the NES DPF02 recessed dishpan system, allowing panels to be fixed or removed in any sequence, standardising panel dimensions at 1,000mm x 500mm simplified logistics and enabled precise alignment across complex geometries. The architectural signage, also produced by NES in copper-anodised aluminium, completes the composition, the 3D halo-lit lettering projects a soft glow across the façade, symbolically linking energy, identity and material craft.
Bringing the Design to Life
The Bunhill Energy Centre stands as both infrastructure and architecture, a working energy plant that contributes actively to its environment, by drawing waste heat from the London Underground’s Northern Line ventilation shaft and reusing it to heat nearby homes, the scheme reduces carbon emissions by approximately 500 tonnes per year, its significance extends beyond engineering, it demonstrates how civic utilities can be reimagined as architectural landmarks. For us the project embodies the convergence of technical precision and design integrity, an approach that transforms functional envelope systems into expressive urban surfaces.
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