Passivhaus retrofit: Warmer, healthier and more comfortable homes

Many people have discovered Passivhaus retrofit through Guy Martin's House Without Bills on Channel 4. The programme highlights how existing homes can be upgraded to dramatically reduce energy use and running costs.

Passivhaus retrofit is a way of upgrading existing homes to deliver lasting comfort, healthier indoor air and much lower energy demand. It focuses on reducing heat loss and improving how your home works as a whole; whether improvements are made all at once or carefully phased over time.

Rather than quick fixes, Passivhaus retrofit provides a clear, evidence-based framework for making homes work better for the people who live in them, now and into the future. The Passivhaus Trust provides trusted guidance, real-life case studies and learning resources to help homeowners understand what’s possible and take the next step with confidence.

Is Passivhaus retrofit right for my home?

Passivhaus retrofit is suitable for most UK homes, including:

Victorian and Edwardian terraces
Post-war semis
Flats and maisonettes
Rural and traditionally built properties

It can be especially effective if you are:

Planning major renovation or an extension
Replacing windows, roofs or heating systems
Experiencing draughts, cold rooms or damp
Looking for long-term energy savings and comfort

Importantly, retrofit does not need to happen all at once. Improvements can be planned and delivered in stages, aligned with budgets, life changes and planned building work.

Shepherd's Barn EnerPHit Plus quote: The house has more than lived up to expectations. It's very resilient, and we are very comfortable. We've never used the radiator in our south-facing bedroom. Very rarely have we used the heating all day. What's so good is the lack of draughts!

What is Passivhaus retrofit?

Passivhaus retrofit means upgrading an existing home so that it becomes far more comfortable, energy efficient and healthy to live in. Instead of focusing on individual measures in isolation, a Passivhaus approach looks at the home as a complete system. Improvements are designed to work together, avoiding unintended problems such as overheating, condensation or poor air quality. A Passivhaus retrofit typically focuses on:

Reducing heat loss through walls, roofs and floors
Eliminating draughts through improved airtightness
Installing high-performance windows and doors
Providing a continuous supply of fresh, filtered air

The result is a home that stays warm in winter, comfortable in summer, and pleasant to live in all year round.

Why EnerPHit exists

EnerPHit is the Passivhaus standard for retrofitting existing buildings. It recognises that every home is different and that some constraints, such as structure, orientation or heritage considerations, may limit what is achievable. EnerPHit sets robust, realistic performance targets while still delivering exceptional comfort and energy efficiency.

Crucially, EnerPHit supports a personalised retrofit plan, allowing homeowners to improve their homes step by step over time rather than committing to a single large project.

Why retrofit to Passivhaus?

The UK has an ageing and increasingly inefficient housing stock. improving existing homes is one of the most effective ways to reduce energy demand, increase health and cut carbon emissions. A Passivhaus approach provides a robust framework for managing the complexity of retrofit and avoiding common pitfalls. For homeowners, the benefits include:

Lower energy demand: substantial reductions in heating needs

Consistent indoor comfort: warm, draught-free rooms throughout your home

Healthier indoor air: continuous fresh indoor air with fewer pollutants

Lower carbon impact: reduced energy use supports sustainable living

Passivhaus retrofit focuses on lasting improvements that work with the building, not against it. Discover many more benefits in detail and why Passivhaus is the proven route to healthy homes.

Harpenden EnerPHit Plus - Quote: Retrofitting has cut our energy bills by 90%. We have so much floor insulation we only need a very low level of underfloor heating, programmed for just 4 hours at night when it's cheapest. We don't need any heating from late March until November.

What about cost, disruption and timescales?

Every home is different, and costs vary depending on the building, ambition and how improvements are delivered. A Passivhaus retrofit approach helps homeowners:

Avoid wasted spend on poorly sequenced measures
Reduce disruption by aligning retrofit with other works
Spread costs over time through phased delivery
Protect long-term value by getting it right first time

Spend smart, not short-term. While high-quality retrofit requires investment, poorly planned retrofit often costs more in the long run. Whole-house planning helps ensure each improvement adds value and performs as intended. Retrofit without regret means no hidden moisture issues, fewer suprises and a home that works year after year. Avoid repeated upgrades that don’t work together and use Passivhaus planning to prevent future rework.

	Conventional retrofit	Passivhaus Retrofit
Comfort	Low	High
Measured performance	No	Yes
Indoor air quality	Variable	Continuous fresh air
Long-term risks	Higher	Lower
Independent vertification	Rare	Standard

Discover our 5 top tips for affordable Passivhaus retrofit delivery.

Tin Barn EnerPHit - Image credit Ellen Christina Hancock

I am about performance and efficiency, whether it’s turbo in engines or heating my house.

To try to convert an existing house to this standard was a massive job because it’s all about build quality. All of these new builds, however many thousand new homes they’re planning on building every year for the next few years, they need to be built right. Because if we don’t build them right we’re going to have the same problem again. Maybe building to Passivhaus is the extreme but it is the gold standard. This is what housing standards need to be.

Do it well, do it once."

Guy Martin, TV presenter

Common homeowner questions

Passivhaus Retrofit has recently been featured on Channel 4’s House with no bills as an example of how homes can achieve very low energy demand. Discover some common FAQ's below - plus more via the retrofit FAQ.

Do I have to retrofit everything at once?

No. Passivhaus retrofit can be planned and delivered in stages. Improvements are carefully sequenced in a whole-house retrofit plan so each step works with future upgrades, allowing you to spread cost and disruption over time.

Will my home still look the same?

This depends on the home & your project brief. Many Passivhaus retrofit projects retain the original character of the building, some have to work within conservation area constraints. External appearance, heritage features and local planning considerations can be accommodated within a whole-house retrofit plan.

Will I need to move out during the work?

Not always. Some retrofit projects are carried out while homes remain occupied, particularly when improvements are phased. Your design team can advise on sequencing to minimise disruption.

Does Passivhaus retrofit help with damp or mould?

Yes. By reducing heat loss, eliminating draughts and providing continuous fresh air, Passivhaus retrofit helps create healthier indoor conditions that reduce the risk of condensation, damp and mould.

Is Passivhaus retrofit expensive?

Costs vary depending on the home and the scope of work. A Passivhaus approach helps homeowners invest wisely by avoiding poorly planned measures that can lead to higher costs over time. EnerPHit is cost-comparable to other deep retrofit standards.

How to get started

If you are considering improving your home, a Passivhaus retrofit approach provides a clear and reassuring way to begin.
You do not need to have all the answers. The first step is understanding how your home performs today. Your retrofit journey typically includes:

Understand your home: Begin with a whole-house assessment to identify where heat is being lost and which improvements will make the greatest difference.
Get the right expertise: Passivhaus designers and consultants are trained to plan retrofit projects that work as a complete system. Their role is to help you understand your options and avoid costly mistakes.
Plan your journey: Retrofit can be delivered all at once or carefully phased over time, aligning with other work such as extensions, roof replacements or window upgrades.

Grants or green finance options may be available depending on your location & circumstances. Green mortgages are accessible to energy efficient homes, and the 2026 Warm Homes Plan incentivises heat pumps and renewables.

Modernist EnerPHit Plus I RDA architects. Quote: I’m so happy with it. Not only is it a beautiful space, but where the world is going crazy with so many utility costs issues, I know that there is no gas – it's all electric and solar with a battery power wall. All these unfamiliar elements work in conjunction with each other – and you discover how to live in the space to its best.

Real homes, real results

Passivhaus retrofit has been successfully applied to buildings across the UK, including terraced houses, semis, flats and rural homes. The case studies show how different homes have been upgraded to improve comfort, reduce energy demand and create healthier living environments. Navigating the challenges of older construction, limited budgets or phased delivery, each project demonstrates how a whole-house approach can be adapted to suit different building types, budgets and homeowner priorities.

Ready to take the first step?

Whether you’re curious or committed, we’re here to help.

Whether you are just starting to explore retrofit or already planning improvements, the Passivhaus Trust is here to help. We are an independent, non-profit organisation providing trusted, evidence-based guidance rather than commercial retrofit services. Our resources are designed to help homeowners build understanding and confidence at every stage.

Don't miss our growing Passivhaus Retrofit playlist on YouTube. You may also be interested in training such as the Passivhaus bitesize course or the Passivhaus tradesperson course to get hands on knowledge. Live in-person Passivhaus Workshops take place in April & November at the NSBRC in Swindon.