Dialling up Passivhaus retrofit across the UK

Improving the UK's existing buildings is one of the biggest challenges in delivering healthier homes, lower energy demand and climate resilience. As government, local authorities and the construction industry increasingly focus on retrofit, the Passivhaus Trust is helping make high-performance retrofit more practical, affordable and scalable. Read our overview of the initiatives underway to make high-quality Passivhaus retrofit more practical, more affordable and easier to deliver at scale.

Why retrofit matters

Guy Martin's House Without Bills. Image credit: North One/ Channel 4

Passivhaus retrofit featured on mainstream TV earlier this year with Guy Martin's House Without Bills on Channel 4 that explored what it takes to turn an archetypal house into the gold standard of energy efficiency. The show was packed with useful advice and tips for any householder interested in cutting bills and carbon emissions from their home, regardless of budget. The programme also helped bring high-performance retrofit into mainstream conversation. Guy Martin’s 'House Without Bills' first aired on Channel 4 on Monday 9 February 2026 at 9pm. Watch it now on catch-up. As a summer comfort addendum, a video of Guy Martin's Ice Box Challenge was released this June, demonstrating how Passivhaus buildings perform in a heatwave, and dispelling some common myths about insulation and overheating.

To help build on the interest in Passivhaus retrofit generated by the 'Guy Martin effect', the Passivhaus Trust ran a series of retrofit case study webinars, which are freely available to view on YouTube. The programmes took a deep dive into one-off domestic projects from barn conversions to Victorian terraces, and heritage cottages to 1970s semis. They provide practical insight for anyone considering their own retrofit.

Growing public awareness is only one part of the picture. The next challenge is making high-quality retrofit more affordable and easier to deliver at scale. Our position paper on Passivhaus Retrofit in the UK makes the case that decarbonisation alone is not enough. Our existing buildings must also be upgraded to deliver healthy, comfortable, affordable homes, and to avoid locking in poor performance for decades to come. Passivhaus retrofit, delivered through the EnerPHit standard, remains the internationally recognised standard for achieving these outcomes. The paper highlights the flexibility of the EnerPHit approach. The EnerPHit component method is presented as the primary and most widely applicable retrofit pathway, with the space heating demand method recommended for buildings with favourable form factor. The paper also situates EnerPHit clearly alongside AECB CarbonLite Retrofit, LETI guidance, and PAS 2030/2035 within the UK retrofit landscape.

Making Passivhaus retrofit affordable

Passivhaus Retrofit in the UK - Passivhaus Trust, 2026

Deep retrofit is often more technically complex than newbuild because it must respond to the constraints of existing buildings. The Passivhaus Trust has developed a new research paper exploring the costs of undertaking a deep retrofit. The study’s findings reveal that EnerPHit compares favourably to other intervention approaches, often sitting within the same cost-per-square-metre region, while providing a more robust framework for quality assurance. There is a growing industry focus on closing the building 'performance gap'. The report highlights how an EnerPHit-informed approach translates investment into measurable value by reliably closing the performance gap and future-proofing the UK’s building stock.

The Passivhaus Trust has developed its top tips for affordable Passivhaus retrofit, including step-by-step and staged approaches. Our new research paper 'EnerPHit Component Step-By-Step' explores possible sequencing of staged step-by-step improvements for a range of housing archetypes, to examine how it incrementally delivers on space heating savings, lower energy bills and reduced carbon emissions..The paper answers such questions as what stage should ASHPs (air source heat pumps) be introduced and whether direct electric heating can be an affordable heating option for flats.

Join the author of the latest EnerPHit Component step-by-step research paper at a panel discussion at UK Construction Week this September to explore these questions and more.

Building industry capability

Passivhaus retrofit can be more complex than newbuild, particularly as more large-scale retrofit programmes emerge across the UK. Even experienced Passivhaus practitioners need to keep informed of the latest strategies and solutions. Our Masterclass webinar series included a focus on the EnerPHit component route to certification and explored large-scale retrofits, including university buildings and schools, estate-wide Passivhaus retrofit tools and retrofit funding. The series is now available to watch on-demand. The Passivhaus Learning Hub offers an extensive range of Passivhaus retrofit guidance papers, training videos, and interactive courses.

If you are involved in the design, delivery or commissioning of large-scale Passivhaus retrofits, do not miss the detailed case study Masterclass on the Firoz Lajli Global Hub this November 2026 in London.

Councils are increasingly developing estate-wide retrofit strategies rather than treating buildings individually. A new Estate Retrofit Toolkit has just been launched by Architype in association with the Passivhaus Trust, Hub East Central Scotland, and City of Edinburgh Council.

FREE to download for the public sector, the toolkit produces clear outputs to support decision making, including: operational energy, cost and carbon; indicative construction costs through to 2045; and suggested retrofit pathways based on building type and condition.

Scaling retrofit

Passivhaus retrofit in the UK is reaching a tipping point. Together these initiatives form part of the Trust's wider programme to help move the Passivhaus retrofit framework from niche projects towards scaled delivery across the UK.
Delivering high-quality retrofit at scale depends on sharing evidence, developing skills and learning from completed projects. The UK Passivhaus Conference 2026 provides an opportunity to hear directly from the practitioners helping shape that future.