Passivhaus Affiliate

Progress being made at Wilmcote House EuroPHit project

Work is underway at Wilmcote House in the Portsea Island area of Portsmouth – a development of three 11 storey blocks of pre-fabricated concrete residential maisonettes being retrofitted to the EnerPHit standard.

The project is already garnering attention after recently been shortlisted for a Constructing Excellence London and the South East Award as an exemplary sustainable project.

The 111 unit development is the only participating case study from the UK in the EU funded EuroPHit project, a Europe-wide programme aiming to retrofit a number of housing developments and commercial buildings to the EnerPHit standard using a ‘step-by-step’ approach.

L-R: New foundations, Existing north facade. Image credits: Helen Brown, Encraft

This approach provides an affordable and manageable way of improving energy efficiency in existing buildings by developing a comprehensive plan of future retrofit measures, detailing how and when to replace certain building components.

A well planned retrofit strategy such as this ensures components are used efficiently for the length of their life span and not unnecessarily replaced, whilst being aware of the possible adverse effects that a retrofit measure may have on other parts of the building.

Architects ECD have vast experience of refurbishing tower blocks having worked on a number of schemes in the UK. For this project, a new steel structure has been designed to allow the envelope to be extended and to enclose the walkway between the maisonettes, improving safety and allowing easier detailing and installation of external wall insulation.

The external wall insulation not only improves the energy efficiency, but allows refurbishment work to be carried out with the occupants in situ, minimising inconvenience for occupants and reducing temporary relocation costs.

L-R: New steel structure, Zehnder MVHR units installed in maisonettes. Image credits: Helen Brown, Encraft

Other key retrofit measures include:

  • Installation of Rockwool external wall insulation surrounding a self-supported steel frame (U-value - 0.14 W/m2K)
  • Replacement of existing windows with high performing triple glazed Ecohaus Internorm windows (U-value - 0.93 W/m2K).
  • Replacement of existing roof and additional Rockwool insulation (U-value - 0.13 W/m2K).
  • New hot water cylinders, electric heating and electric showers.
  • Zehnder mechanical ventilation heat recovery (MVHR) units.
  • Extension of living areas and creation of 'sun rooms'.
  • Enclosure of communal walkway with the creation of an additional entrance.
  • Structural concrete repairs & decorations to external/ communal areas.


Project team:

Client: Portsmouth City Council

Architects: ECD Architects

Detail design: Sustainable By Design


Contractor: Keepmoat Regeneration

Structural EngineersCurtinsCarter Clack

Further information:

Previous PHT story - 'Wilmcote House retrofit due to start onsite in January', 28th November 2013

ECD case study - Achieving EnerPHit at scale: Case study of Wilmcote House tower block refurbishment

Wilmcote House. Front facade

Wilmcote House. Existing front facade. Photo credit: ECD Architects

28th April 2015

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