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Wilmcote House: an award winning retrofit to the Passivhaus EnerPHit standard

Wilmcote House Residential Refurbishment


Client: Portsmouth City Council
Project Value: £12.9m
Brief: Refurbishment of 11 storey, 3 tower, housing block
Sustainability Initiatives: External wall insulation; heating systems; roof insulation; high performance windows.

The refurbishment of Wilmcote House has been designed using a fabric first approach in keeping with the Passivhaus/EnerPHit standard. This strategy involved wrapping the existing accommodation blocks in external insulation in a manner that protects the fabric from the weather and external thermal conditions, and provides a stable and comfortable internal environment for residents. The EnerPHit refurbishment standard not only achieves significantly higher performance than current regulations for new build housing, it also ensures the building performs as designed. The building has been clad in high quality non-combustible mineral wool insulation and all flats have been fully compartmented thereby preventing the spread of fire between flats both internally and externally.

Wilmcote House was originally constructed as a concrete prefabricated structure in 1968 using a large panel ‘Bison REEMA’ variant system. It consists of three 11-storey linked residential blocks which provide much needed affordable housing for Portsmouth City Council. With no place to relocate the residents within these 107 units, the City commissioned ECD for the building’s regeneration to be achieved with the residents in occupation.The project works included:

  • Structural remediation of external structure
  • Installation of insulation to external walls
  • Replacement of glazing
  • Flat roof conversion with upgrading existing levels of roof insulation
  • Provision of a new heating system
  • Decoration of external concrete areas not to be overclad or rendered
  • Installation of fire rated composite entrance doors to properties


  • Winner: RICS Awards – Design Through Innovation category 2018
  • Winner: RICS Awards – Regeneration category 2018
  • Winner: Constructing Excellence Awards – Sustainability Category 2018
  • Winner: SHIFT Awards – Best Retrofit Project 2017