The world is in a climate emergency, and nowhere is this more apparent than in our coastal communities. Here in East Sussex (where Mountain Fold is based), we’re already experiencing what climate scientists have been predicting: more intense storms, unpredictable rainfall, and the creeping reality of rising seas. With buildings responsible for around 25% of UK greenhouse gas emissions, how we design and build our homes isn’t just about comfort anymore – it’s about survival and stewardship.
But with regards to operational energy, we already have the solution. It’s been quietly proven in over 37,000 buildings worldwide for more than thirty years, reducing energy use while providing higher levels of comfort. It’s called Passivhaus, and it might just be the most optimistic response to our climate crisis.
A Standard Born from Oil Shocks, Perfect for Climate Crisis
Passivhaus emerged from collaboration between Dr. Wolfgang Feist and Professor Bo Adamson in 1988, when oil price volatility had everyone thinking about energy independence. Their radical idea? Design buildings so efficient they barely need heating at all. The first Passivhaus buildings, completed in Germany in 1991, have been delivering on that promise ever since – using up to 90% less energy than conventional buildings.
What makes this particularly relevant for East Sussex isn’t just our exposed coastline or our variable seaside climate. It’s that Passivhaus principles work brilliantly with our specific challenges: driving rain, salt-laden winds, and the need to stay comfortable without relying on fossil fuels that we know must stay in the ground.
The Five Principles: Simple Ideas, Profound Impact
Passivhaus is performance-based rather than adhering to any particular construction method or aesthetic style. In the UK, this is expressed in five interconnected principles that create buildings that are genuinely fit for the future:
1. Continuous Insulation – Your Building’s Warm Coat
Think of insulation like a winter coat. If your coat had little or no padding, holes at the pockets, gaps at the cuffs, or a broken zip, you’d still feel cold. Passivhaus insulation wraps the entire building envelope in a thick continuous coat without gaps or weak spots. In practice, this means walls about twice as thick as standard UK construction, but the payoff is extraordinary.
Those cold spots near windows? Gone. The draft from that corner of the room? Eliminated. The temperature difference between standing near a window and sitting by an internal wall? Virtually imperceptible. This isn’t just about energy savings – it’s about creating spaces that feel consistently comfortable, where you naturally gravitate to windows for the view, not away from them because of the cold.
2. High-Performance Windows – Views Without Compromise
Here’s something that surprises people: in a Passivhaus, windows can be opened whenever you want. The difference is, you won’t need to. Triple-glazed windows with insulated frames maintain interior surface temperatures of at least 17°C, even when it’s freezing outside. This eliminates the convection currents that create that uncomfortable ‘cold radiation’ feeling near conventional windows.
For our coastal sites in East Sussex, this is transformative. You can have floor-to-ceiling glazing facing the Channel without sacrificing comfort or efficiency. The windows become net energy contributors, carefully balanced to harvest winter sun while preventing summer overheating through calculated shading – whether from deep reveals, overhanging eaves, or external blinds that can be adjusted seasonally.
3. Airtightness – Keeping the Elements Where They Belong
With a standard home, much heat loss happens due to a ‘leaky’ building fabric, and the unregulated passage of warm air to the outside. Passivhaus aims to eliminate this as much as possible, by building it air-tight.
This isn’t about living in a sealed box – it’s about controlling exactly where and how air enters your building. An airtightness level of 0.6 air changes per hour (compared to 5-10 in typical UK homes) means no unexpected drafts, no moisture sneaking into your walls to cause mould, and no heat escaping through gaps you didn’t even know existed.
4. Mechanical Ventilation with Heat Recovery – Fresh Air, Warm Air
This is where the magic happens. A Passivhaus ‘breathes’ through a mechanical ventilation system that brings in fresh, filtered air while recovering up to 95% of the heat from the outgoing air. Imagine opening your windows for fresh air on a cold day, but the incoming air arrives pre-warmed and pollen-free.
The air quality in a Passivhaus is revelatory. Cooking smells don’t linger. Bathrooms don’t steam up. Bedrooms feel fresh even with the doors closed all night. For the increasing number of people with allergies or respiratory conditions, it’s life-changing. The system runs on about the same energy as a couple of LED lightbulbs – a small price for constant fresh air.
5. Thermal Bridge-Free Construction – No Weak Links
Every material conducts heat differently. Where materials meet – steel beams penetrating walls, concrete balconies extending from warm rooms – heat finds a shortcut out. These thermal bridges are like leaving a tap dripping: insignificant-seeming losses that add up to serious waste.
Passivhaus details eliminate these bridges through careful design. Balconies are thermally separated. Service penetrations are meticulously planned. Even the screws holding the insulation are considered. It’s this attention to detail that enables such remarkable performance – not any single dramatic gesture, but hundreds of small decisions made right.
Learning from Local Wisdom
What fascinates me about applying Passivhaus in East Sussex are the ways in which it aligns with our local vernacular architecture, and how it can be developed. The thick chalk and flint walls of traditional Sussex buildings provide thermal mass, storing heat during the day and releasing it at night. The small windows of fishermen’s cottages in Hastings Old Town? They’re minimising heat loss while protecting against driving rain.
I’m not abandoning these lessons, but looking at why particular features evolved and what lessons they have for the world today. Where traditional builders used intuition and local materials, we now have building physics and performance data. Where they accepted discomfort as inevitable, we know we can deliver consistent comfort using less energy than ever before.
A Real Project: Firs Field
On the Firs Field project, I worked first as Passivhaus consultant and later took over as architect after planning permission was granted. Working with the Passive House Planning Package (PHPP) – the energy modelling heart of every Passivhaus – we achieved a heating demand of just 13 kWh/m²/year (below the 15 kWh/m²/year Passivhaus standard).
Every decision interconnects, and the PHPP allows informed choices to be made. Here, the size of large southwest-facing windows was a balance between capturing stunning rural views and an increased risk of overheating. Partially moderated by a shading structure to the south corner, this was kept to 7%, below the 10% set out in the standard.
Prefabricated timber panels from Eden Insulation in Cumbria, filled with cellulose insulation and wrapped in high-tech air- and weather-tightness membranes, formed the walls and roof, creating a high-performing building fabric nearly three times as efficient as one that merely complied with the Building Regulations.
What This Means for East Sussex
As our climate shifts – with predictions of wetter winters, drier summers, and sea levels rising enough to threaten parts of Eastbourne – Passivhaus offers remarkable resilience. These buildings maintain comfortable temperatures through power outages. They protect indoor air quality when outdoor pollution peaks. They adapt to temperature extremes that would make conventional buildings unbearable.
Our local councils have declared climate emergencies and are actively supporting sustainable development that demonstrate genuine environmental leadership. This isn’t just about compliance – it’s about creating buildings our children will thank us for.
The Wider Context
With thousands of homes across East Sussex and the UK needing energy upgrades, and new homes being built every year, we have choices to make. We can continue building to minimum standards, creating homes that will need expensive retrofitting within decades. Or we can build them right the first time.
The government’s Future Homes Standard, due to be published this year, will require new builds to produce 75% less carbon than current regulations. Passivhaus already exceeds this. By choosing Passivhaus principles now, you’re not just future-proofing against regulations – you’re future-proofing against energy prices, climate extremes, and the very real health impacts of poor indoor air quality.
Beyond Standards: A Philosophy of Hope
What draws me to Passivhaus isn’t just the technical elegance or the energy savings, though both are compelling. It’s that it represents a profoundly hopeful response to our climate crisis. Instead of asking people to sacrifice comfort for the planet, Passivhaus delivers buildings that are simultaneously more comfortable AND more sustainable.
This isn’t about reducing your quality of life to save energy. It’s about living in spaces that feel naturally comfortable year-round, where the air is always fresh, where energy bills become almost irrelevant, and where your home actively contributes to solving our climate crisis rather than worsening it.
Your Next Step
Whether you’re planning a new build, an extension, or wondering how Passivhaus principles might transform your existing home, the best time to start thinking about these ideas is at the very beginning. That’s when they can be seamlessly integrated into the design, creating architecture that feels inevitable rather than imposed.
Are you ready to explore how Passivhaus principles could work for your project? I’d love to discuss your vision and how we can create a building that’s not just fit for today, but resilient for the decades ahead.
Get in touch for a consultation – let’s explore how your project can be part of the solution.
*In 2018 I certified as a Passivhaus Designer. While my certification lapsed in 2023 due to the specific recertification requirements, the knowledge and passion remain. I’m actively working toward recertification and continue to apply these principles to every project, whether formally certified or not.