Can EnerPHit at scale fight fuel poverty?

At the 2018 UK Passivhaus Conference, a session dedicated to retrofit focused on solutions to help deliver zero carbon targets for existing buildings. Amongst Energie Sprong, & whole house deep green renovations was Wilmcote House – the sole UK scheme participating in the EU funded EuroPHit project. Located in Portsmouth, Wilmcote House is a deep green step-by-step regeneration of a 1960’s concrete pre-fab construction. It has been modelled in PHPP with the original intention to target EnerPHit. Although it hasn’t yet been possible to achieve EnerPHit critera, it is a project of significance that may provide a new model for tackling estate refurbishment & fuel poverty.

Wilmcote House ©ECD Architects

Owned by Portsmouth City Council (PCC), Wilmcote House is over 40 years old and within the 10% most deprived areas of England. Research carried out by the University of Southampton discovered many units had an EPC rating of band D and several residents could not afford to heat their homes to World Health Organisation comfort levels. Without refurbishment it would be uninhabitable for residents, and costly to maintain in the short-term. Key priorities were to tackle fuel poverty and health & security issues, whilst upgrading the building stocks maintenance and performance.

Demolish, refurb or retrofit

A financial appraisal at feasibility stage suggested that a fabric-first approach adopting a high specification of work would be more economical over a 30-year plan than to demolition & replace the 3 blocks. Residents were kept in-situ whilst works were carried out, avoiding community displacement.

Key Stats

11 storeys
3 inter-linked blocks
111 flats
Cost £13m
Start date: July 2014
Completion: 2018

Lessons

As to be expected with a project of this scale keeping residents in-situ, the delivery & construction were not without challenges. Residents have endured disruption caused by on-site construction delays. This has resulted in delays to the final air-test.

An unexpected increase in the primary energy demand, due to some existing storage heaters being retained, will be rectified by adding a small amount of PV's to the roof in the future.

The University of Southampton continue to monitor the building post-construction and now have positive results from two summer seasons and one winter season. Preliminary feedback suggests the properties energy performance is much improved translating to lower fuel bills for tenants. The London School of Economics are concluding their final resident interviews and will be launching their final report in January (2019).

Wilmcote House ©ECD Architects

Key Team

PHT Patron, ECD Architects, were selected as Multi-disciplinary lead consultants for Wilmcote House by PCC via an OJEU tender process in 2012.

Client: Portsmouth City Council (PCC)

Architects: PHT Patron ECD Architects

Detail design: Sustainable By Design

Consultant: Encraft, Keegans

Contractor: Engie Regeneration (formally Keepmoat Regeneration)

Structural Engineers: Wilder Carter Clack

Wilmcote House

Dissemination

Wilmcote House ©ECD Architects

Investing in a high specification & build quality has increased the longevity of the build. As well as improving the residents living conditions, the buildings use has been extended with reduced maintenance and decarbonised. The retrofit build cost was approximately £920/m². This is comparable with new-build housing to similar density & quality, providing a strong business case for upgrading existing concrete buildings at scale.

The experimental scheme proves that large scale deep retrofits targeting EnerPHit Standards offer enormous improvements to residential & commercial building occupants & owners. ECD Architect’s summary report highlights that the Passivhaus methodology offers transparency, quality, flexibility and most importantly, proven performance. In the long term, it is more economical than adopting modest fragmentary energy efficient works that can often cause unintended damage & underperform, locking in inefficiencies.

The report goes further to state how the Government could support much needed growth of the retrofit industry by providing clear target requirements, along with financial incentives & consumer guidance to early adopters.

Whilst important to acknowledge there is no one-stop-shop fix for all retrofits, the case study offers a potential solution to roll out across a multitude of existing large-scale multi-story concrete tower blocks in disrepair.

Hear more about Wilmcote House at a forthcoming webinar on 31st January hosted by Inside Housing. For rmore social housing case studies, visit our Passivhaus Social campagin.