Retrofitting: An EnerPHiT insulation overhaul for Wilmcote House

Wilmcote House in Portsmouth equired significant improvements including retrofit insulation upgrades to ensure quality of life for residents.
Wilmcote House Property

High-rise, high-density housing estates built by local authorities in the 1960’s remain a prominent feature of Britain’s urban landscape – but the thermal performance of these buildings often falls below modern standards. One such development is Wilmcote House in Portsmouth, which required significant improvements including retrofit insulation upgrades to ensure quality of life for residents…


The project

Across a four-year programme, over 100 residences within Wilmcote’s three 11 storey blocks were set for upgrades to provide comfortable, safe and thermally-efficient homes for residents that will endure for years to come.

Wilmcote House would become the largest EnerPHiT (the retrofit equivalent of Passivhaus) standard scheme yet delivered with residents in-situ. A key objective of the major renovation, designed and led by ECD Architects, was the creation of an environment capable of supporting the health and wellbeing of tenants.


The challenge

Wilmcote House was identified as one of Portsmouth City Council’s high-rise developments most urgently in need of improvement. Fuel poverty was a cause for concern, as well as damp, mould and condensation.

The University of Southampton aided by installing data loggers into properties which revealed compelling results. Residents were not heating their homes to the World Health Organisation comfort level of 18°C, as their electric heating was too expensive.

Following a detailed appraisal, Portsmouth City Council engaged ECD Architects to design and lead a substantial renovation tasked with delivering the scheme to the ambitious EnerPHiT standard in a bold, fabric first approach. They targeted a reduction in dwelling heating demand by 90% and a minimum 30-year extension to the lifetime of the estate, with the entire project carried out as residents remained in-situ.


The solution

ECD’s whole building EnerPHiT solution centred on deep retrofit. This involved the super-insulation of Wilmcote House using a combination of several products and systems, including a Rockpanel® cladded façade system and a combination of ROCKWOOL External Wall and Flat Roof insulation together with a selection of the company’s fire stopping and fire protection products.

The ROCKWOOL external insulation was fitted as a 300/400mm zone fixed to newly assembled, external steel frames to insulate and wrap the entire building. The result is improved thermal performance and enhanced air tightness, reducing draughts, condensation and mould growth.

Other works at Wilmcote House included roof replacement, installation of triple glazed windows, extension of the living areas, and more efficient heating and hot water and adjustment of the ventilation with heat recovery system.

The refurbishment brought the community together by improving the appearance of the estate and investing occupants with a greater sense of pride in their surroundings.

Community engagement was a major theme throughout the project. Residents of Wilmcote House were comprehensively consulted on the refurbishment proposals via a series of resident open days and feedback sessions, and dialogue was maintained throughout the build.

The social and performance outcomes of the project will continue to be monitored by a partnership between ROCKWOOL, the London School of Economics (LSE), and the University of Southampton.


The result

Wilmcote House is the largest residential EnerPHiT project delivered with residents in-situ in the world and is a testament to what can be achieved by taking a holistic, fabric first, people-focused approach to building refurbishment.

The Council has dramatically improved the living environment and quality of life of residents, investing in people, not just the physical condition of the housing stock. The anecdotal evidence and feedback received so far has the project already proving to be a big success, as residents in completed properties experience the positive impacts on their health, wellbeing and reduced fuel bills.

In 2018, the scheme received two RICS awards – one for Design Through Innovation, another for Regeneration, and it also secured a Constructing Excellence Award for Sustainability.

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