Vane Close

Project type: Residential
Project location: Hampstead, London

Deeper Green designed a new extension and refurbishment project on a residential property in North London. It was, in fact, the sixth project Ian McKay had undertaken for the same client since the late 1990’s. This latest venture involves a conjoined pair of late 1960’s-built townhouses just off Hampstead High Street. The work includes a complete remodelling of the ground floor as well as the erection of a new energy efficient extension to replace an ageing conservatory.

Vane Close was a compact yet highly complex project involving a partial house refurbishment, elements of eco-retrofit as wall an ambitious single-storey green roofed extension. Spatially the extension linked the side entrance of the house with the kitchen and the rear garden. The long narrow footprint of the former conservatory was enlarged by creating a new glazed bay and to form a new living space with a stronger sense of repose and visual links to all the adjoining spaces.

Deeper Green worked with energy engineers, Enhabit, to devise a low carbon heating and ventilation strategy for this fascinating project which also included the installation of an air source heat pump and mechanical ventilation system with heat recovery. New and larger radiators were used on the upper floors, and underfloor heating was integrated across the ground floor constructions, some of which as an eco-retrofit. This allows the air source heat pump to operate more efficiently with lower flow temperatures.

The architectural handling of the interiors and exteriors took inspiration from the short-lived, but now much-admired, post-war phase of English Brutalism, which is very much the tradition within which the original townhouses were conceived. Deeper Green worked closely with the clients to derive an interiors palette of materials and colours that would bring a contemporary twist to the post-war aesthetic. Ash was chosen for the ceiling finish of the new main space as well as for the fitted furniture. In part this decision recognised ash dieback disease in English woodlands.

The new extension was conceived as a timber-framed superstructure. This helped drive down the embodied carbon impacts of the proposals. A reclaimed imperial brick was chosen for the cladding of the timber frame, and the use of a moderate strength hydraulic lime mortar ensures the continued circularity of use, of this already reused building material for future generations.

The client was reluctant to lose the very high levels of daylight of the original conservatory space so, together with the architect, design options were explored before settling on a strategy based around one very large motorised opening triple-glazed roof window (with a motorised internal blind) and a glazed top to the new bay window. The scheme also incorporates two high quality sun pipes which use super clear crystal glass domes with polished aluminium light ducts to bring daylight into the WC space and side entrance lobby.

A case was made by Deeper Green to achieve a biodiversity net gain with a green roof for the new extension. The clients agreed and they are delighted with the results. The wildflower and grassland seed mix creates a stunning mini-landscape below the upper floor windows and can even be seen on approaching the house from the uphill vantage point off Hampstead High Street. Where before there was just a glass conservatory, the property now boasts a meaningful enhancement of natural habitat with the wider benefits of summer heat buffering to the interior spaces and mitigation of the local area’s ‘urban heat island effect’. It also slows rainwater runoff which is an important technical response to the prolonged and heavier rainfall we are experiencing as a result of climate change impacts.