Kingswillow House by Graham Handley Architects

Kingswillow House, Cambridgeshire, was presented at the AT Awards live finals on 20 September 2023 to a jury comprising Simon Allford, Esther Robinson Wilde, Ed Jarvis, Amin Taha, Patrick Bellew, and Chair Lee Mallett. Read about how the project has stood the test of time.

Credit: Emma Harper

Completed
2019

Built in 1938, Kingswillow House in Cambridgeshire, epitomises Modern Movement architecture. Set within substantial gardens and enjoying views across open countryside, the grade II-listed structure had fallen into disrepair before Graham Handley Architects was appointed to undertake a sensitive yet far-reaching renovation scheme in 2015.

While the works undertaken have been extensive, the visibility of the alterations is minimal, and new finishes and fixtures remain in keeping with the original character of the house. Established at the outset, an open and ongoing dialogue with the conservation officer has been critical to the overall success of the project.

Credit: Emma Harper

The initial focus was to make the house warm and dry. Through negotiations with the conservation officer, the envelope was externally insulated and rendered, significantly improving thermal performance. Concrete canopies, which extended through the external walls and created cold bridges, were insulated internally using ultra high-performance Aerogel insulation set within the plaster build-up. Parapet walls were increased in height, allowing the roof to be completely insulated.

The original steel-framed windows have been restored and upgraded to provide improved U-values (with double-glazing, removal of warping and draught sealing), and given an extended lifespan by galvanizing and powder-coating. Elsewhere, ground source heating has been added, along with large runs of photovoltaic panels screened from view by the raised parapet walls. Internally, the floors were insulated and underfloor heating installed. Radiators used in bedrooms have been replaced with more efficient replicas.

Retrofitting one-off houses of this calibre is rare, and understanding the impact of decisions taken and sharing the learning gained will be critical to the success of similar future retrofit projects.