Listed Modern Movement House

This RIBA East 2020 shortlisted project, involved the renovation and thermal upgrade of the Grade II Listed, modernist house by Dyson and Hebeler. Kingswillow House is a unique, inter-war family home that epitomises Modern Movement architecture.

The house was published in the architectural press at the time of its construction, and technically ahead of its time, but after decades of neglect, was cold, damp and draughty. The large flat roof leaked and the original Crittall windows were so rusted that they would no longer close. Reinforced concrete canopies and lintels, ahead of their time when constructed, were rusting and breaking apart, and the brickwork was spalling. The house was completely un-insulated, and eerily cold.

While GHA could have taken an essential repair only approach to the project which is common for most listed buildings, it became apparent a full thermal upgrade was required to provide a comfortable and energy efficient family home for the long term.

With such a pure, sculptural form of architecture, the original house was challenging to upgrade, and any works were going to affect its appearance. Therefore all decisions have been a balance of heritage value against environmental performance. This involved a close working relationship between the client, GHA, conservation and building control and has successfully resulted in a 91% reduction in energy consumption, which translates to an 86% reduction in CO2 emissions.

The thermal upgrades to the fabric constituted wrapping the building in a layer of insulation, through the application of Sto EPS insulated render, insulation of the timber suspended ground floor, and insulating the roof. The internal walls were also upgraded with internal Aerogel insulation to alleviate cold bridging where the concrete overhangs and lintels pass though the new thermal envelope. The original windows were fully refurbished and upgraded with energy efficient slim-line double-glazing. Although modern standard air-tightness measures were not fully possible due to the historical nature of the buildings’ fabric, and need to maintain a breathable structure, however GHA took steps where possible to minimise heat losses.

In addition to building fabric upgrades sustainable technology was installed reducing the buildings’ reliance on fossil fuels. The inefficient oil-fired boiler was replaced with a Ground Source Heat Pump. The GSHP was paired with underfloor heating within the newly insulated house to allow for the most efficient energy transfer coefficient.

Photovoltaic Panels were installed on the roof and chosen to compliment the GSHP, with the size of the roof allowing for a 4KW system.

Kingswillow was Highly Commended in the 2020 Building Magazine Awards in the Building Performance category and Highly Commended in the 2021 Architects' Journal Retrofit Awards.

Energy info
0.45W/m2 k – Walls
0.17W/m2 k – Roof
1.90W/m2 k – Windows
Total Gross Energy Consumption:
Total Onsite Energy Generation: