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.
Passivhaus retrofit featured on mainstream TV earlier this year with Guy Martin's House Without Bills on Channel 4 (pictured) 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.
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.
