MVR, London

Energy efficient home extension

Iqbal Johal

Returning clients of Knott Architects, approached them with a familiar challenge: a much-loved home whose fabric, performance and relationship to the garden no longer matched the way they wanted to live. Rather than simply adding more floor area, the project set out to reframe the lower ground floor as a generous, light-filled living level..

energy efficient home extension

Improving Comfort and Energy Efficiency in Modern Home Extension

The brief combined energy upgrade with spatial transformation. High performance windows, substantial thermal insulation and a new efficient heating system dramatically improve the building’s energy profile, reducing heat loss and future running costs. These fabric-first interventions underpin the extension, ensuring that new space is not just visually impressive but comfortable and economical to occupy.

Spatially, the lower ground floor was extended beneath the existing upper ground floor and pushed out into the garden, creating a deeper, more useable living zone. Where garden space was taken, a new green roof gives back at a higher level, softening views from above and supporting biodiversity. This layered section allows the house, extension and landscape to interlock rather than compete.

Galvanized Steel Supports Sustainable, Low-maintenance Extension

At the core of the architectural concept is an exposed galvanized steel structure. New beams and columns support the house and remain fully visible. Here, hot dip galvanizing is crucial: it provides robust corrosion protection at these vulnerable junctions, allowing the steel to remain slender, honest and low-maintenance over the long term.

The extension reads externally as a galvanized steel and glass screen, running diagonally across the full width of the garden. Above it, a shallow tray roof cradles the green roof. This combination of glass, planting and metallic envelope gives the extension a precise, almost infrastructural clarity against the softness of the garden.

A triangulated, demountable framework of galvanized steel poles projects outward, offering a rig to which the family can attach homemade awning sails. This lightweight armature can support adaptable, seasonal layers without compromising durability or finish.

Material Honesty

Internally and externally, materials are left largely ‘raw’: timber, concrete and glass are expressed as found, and the galvanized steel is used unpainted and celebrated. The distinctive, variegated zinc surface extends to external light fittings and rainwater goods, tying together structure, detail and furniture into a coherent language.

In architectural terms, the project shows how high quality extensions can be achieved when galvanized steel is treated not just as a technical solution, but as a primary design material. One that can carry structure, define form and deliver a resilient, finely crafted structure that connects house and garden.

Project Gallery
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Project Information

Architects: Knott Architects
Structural: Engineers: MBOK
Contractor: Rolandas Sinkevicius

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