Sanya Polescuk Architects has retrofitted an unloved 1950s terraced house to make a home that is refreshed, expanded and entirely fossil-fuel free. Sanya Polescuk explains the practice’s approach to balancing conservation issues with the urgent need to inject our housing stock with a new and sustainable lease of life.


The pivot window frames the bay tree in the centre of the garden and the new timber-clad garden studio beyond.

The question of how to retrofit our housing stock to be low energy and high efficiency is very much at the forefront of professional discourse. According to Scaling Up Retrofit to 2050, a white paper produced by the Institution of Engineering and Technology and Nottingham Trent University, 1.5 homes a minute need to be lifted to EPC rating C or better to meet national targets.

Currently 70% of our existing housing stock does not meet C rating. The challenge for the private sector is to persuade clients that it needn’t be prohibitively expensive to improve the environmental performance of their house.

This project,a refurbishment of a modest house in London’s Belsize Park, is part of our practice’s ongoing interest in finding ways to retrofit our existing building stock that respect our architectural heritage and are a realistic option for clients with limited budgets and ordinary homes.

Part of an ugly duckling terrace of five houses in a long street of Victorian and Edwardian villas, this two-storey terraced house in London’s Belsize Park had long been unsaleable and was clearly unloved. The original dark mahogany floor, concrete tiles and heavy clinker type bricks felt as though they belonged to another era – a combination of Ernő Goldfinger’s 1930s modernist housing at nearby Willow Road and Chamberlin, Powell and Bon’s Barbican Centre, a little further afield. Our challenge was to respect and refresh this architectural language and implement a fabric-first approach to create an expanded home that was entirely fossil-fuel free.


Part of a two-storey terrace in London’s Belsize Park, the house is a throwback to an architectural language that has fallen out of fashion.

We developed a strategy based on the following principles:

• Deep retrofit using traditional procurement with a non-specialist contractor to build, and specialist consultants to analyse thermal elements and energy use.

• A fabric first approach: high levels of insulation and a careful air-tightness strategy supported by WUFI calculations.

• An on-site mix of micro-generation: solar hot water and photovoltaics used in conjunction with an air source heat pump. Energy modelling showed that the addition of a home battery would mean self-sufficiency for 9 out of every 12 months.

• Original features retained and restored: solid hardwood floors were restored off site and relaid over new underfloor heating; doors were retained and refinished; and light fittings were made good and repainted to reduce contributions to landfill.

A new kitchen has been located at a pivotal point between the rear garden and the living space and is now the heart of the home.

Unfashionable pavers and concrete bricks were saved from the skip and relaid in a new composition creating a pathway from the new extension to the studio.

The practice’s ethos has always been to reduce waste and to find new purposes for found fixtures and materials. We kept and celebrated this weighty, hewn feel and took it further into a new, rear extension and studio at the back of the garden.

On the ground floor, the rich palette of mid-century colours is set against the restored mahogany parquet, new Barbican-like tiled floors and light birch plywood fitted furniture. Up the original stairs, there are three bedrooms, made to feel bigger by the open-roof timber structure and bright yellow painted ceilings hovering above; and two neat, all white-tiled and multi-colour pointed bathrooms.

The timber open roof structure and yellow painted ceilings make the bedrooms feel bigger.

Two neat bathrooms are white tiled and multicolour pointed.

Originally, a small, street-facing kitchen looked out on to a large road junction. This space has been repurposed to house a combination of water cylinder, utility and bicycle storage. A new kitchen is now the heart of the home, located at a pivotal point between the rear garden and the living space. The timber structure is left exposed and the weighty, south-facing brick extension is hung lightly. The large pivot window frames the statuesque bay tree in the centre of the garden. Unfashionable pavers and concrete bricks, saved from the skip, are relaid in a new composition leading towards a small, timber-clad garden studio. Although designed pre-pandemic, the home-working environment has immediately come of age, allowing separate workspace in a calm but textural space with exposed timber structure and a carpet of bricks leading all the way from the kitchen.


The solid hardwood floors were restored off site and relaid over new underfloor heating, while original features have been retained and restored.

With the house set to be a temporary rental property and eventually a retirement home, the materials chosen are there to last – tough, easy to clean but also warm and homely with an emphasis on low VOC and no undesirable ingredients. For example, the linoleum on the floor and joinery has no vinyl. Materials are 97% natural and contain nearly half recycled content. Hard wax is used to finish all the timber.

A fabric-first approach was used as a refurbishment method. This meant improving the thermal properties of the external walls, roofs and ground floor and eliminating drafts. The cavity walls were filled with blown insulation and further upgraded with internal insulation. All wall vents were retained externally but blocked internally. Instead, mechanical ventilation with heat recovery (MVHR) was installed to create a warm, comfortable environment and reduce energy demand. Rather than a gas boiler, heat and hot water are supplied by an air source heat pump (ASHP), coupled with PV and solar-thermal roof panels.


The long front garden faces a wide pavement and a broad busy road and seemed a perfect location for the ASHP. Shrouded in a custom-designed enclosure, it is hardly detrimental to the conservation area. Despite that, an energy-sapping fight with planners nearly ruined the wellbalanced and sustainable energy design.

A forward-thinking fossil-fuel strategy has clearly not yet filtered through to other areas of policy.

The new studio at the end of the garden provides a space for home working that is apart from the main house but echoes its materials palette and language.

Light birch plywood fitted furniture is set against the restored mahogany parquet and Barbican-like tiled floors.

Download Drawings


Sanya Polescuk Architects
Ling Engineering
M&E consultant
Main contractor
Quantity surveyor
AJ Oaks & Partners

Brick ceiling system
Grestec and Ketley
Duravit, Bette, Hansgrohe
Marmoleum Flooring
Farrow & Ball
Ketley Brick
Kitchen Appliances
John Lewis
Kitchen worktop
Granite Transformations