GoldSmith Street Norwich – Stirling Prize Award Winner 2019


The social housing development of 105 ultra-low-energy homes for Norwich City Council, is the first social housing scheme to be shortlisted and win the coveted Stirling Prize. The prestigious award from RIBA, chaired by Julia Barfield, praised Goldsmith Street “as a modest masterpiece. It is high-quality architecture in its purest most environmentally and socially-conscious form.”

Cygnum Managing Director John Desmond stated…. “We are immensely proud of the major role Cygnum Building Offsite played in this project. We designed, manufactured and installed the highly insulated timber frame structures to a tight program and exceptionally high-performance standards. Our team were outstanding! Well done to Mikhail Riches and all involved”

As well as achieving the rigorous Passivhaus standard, the delivery team was faced with significant additional challenges including a short lead time and a limited budget. Installing such a large number of houses with limited space and access required careful planning and sequencing. The offsite nature of timber frame meant this could be done long in advance of work commencing on site. A delivery schedule was agreed (and adhered to) at the outset and this allowed the main contractor to synchronise other trades with precision around Cygnum’s works. Houses were checked for airtightness on an ongoing basis and cellulose insulation blown in under pressure eliminated performance gap concerns and added to the environmental credentials of the scheme.

Good timber frame engineering also resulted in an economic design, which in general terms means using less materials. In addition to this, in the building’s thermal envelope, less timber leaves more room for insulation hence the thickness of the walls and roof were kept as slim as possible.

This exemplary energy performance was achieved using a timber-based build approach –chain of custody certified throughout – that reduced the developments embodied energy

Year Constructed2018
ArchitectMichail Riches
Design Features
  • 105 social housing units, a mixture of 45 houses and 60 flats all built to the rigorous Passivhaus Standard
  • Seven terrace blocks arranged in four rows and bookended by three-story flats, the design exploits angled sloping roofs to maximise daylight throughout the development and prioritises pedestrians over cars.
  • Future maintenance has been minimised by designing flats whereby every flat has a front door onto the street, with its own staircase and lobby at street level- designing out all internal common parts.
  •  The design seeks to provide sunny, light-filled homes with very low fuel bills of approximately £150 per year. In the main, these properties will be socially rented.
Timber Frame Features
  • Cygnum Passive system featured a twin-wall sheeted on both sides, with a membrane on the inside forming the airtight layer.  The build-up featured an 89mm stud, and a second 67mm stud, fully cellulose-insulated with an overall wall thickness of 399mm, which is designed to be thermal bridge free.
  • The intermediate floors and roofs were factory assembled cassettes with the cellulose-insulated zone to the roof using 400mm engineered joists.
  • To achieve passive certification, we had to ensure that everything materials, detail design and factory quality control standards were to the highest level. Four key factors had to be addressed: U-values, airtightness, thermal bridging, and interior surface temperatures.