Belfast showcases Passivhaus innovation and climate action

The conversations, connections and ideas shared by over 600 delegates at last weeks UK + IRL Passivhaus Conference 2025 have left us all energised and inspired to push the boundaries of how Passivhaus can be the mainstream, evidence backed solution to our changing climate. We may have said goodbye for now to the emerald isle, but we've crossed the sea with a real sense of momentum and optimism in the air.

UK + IRL Passivhaus Conference 2025 | Image credit: PHT

From thought-provoking presentations to hands-on workshops, technical masterclasses and passionate debates over coffee (or a pint in the pub), Belfast was truly buzzing with the spirit of innovation and collaboration that defines the Passivhaus community. Key conversations explored how Passivhaus is now mainstreaming in the industry, how well placed Government investment is helping to accelerate projects in Northern Ireland and the changing mindset of the whole construction industry that Passivhaus is a robust, proven and achievable option.

What truly stood out, however, was the pride with which the speakers shared not only their experiences, but the collaborative working that Passivhaus inspires and promotes. As we reflect on the day, we celebrate the Passivhaus community, whose commitment to tackling the interwoven challenges of climate, health and cost of living crisis head on continues to drive progress in building design and performance.

Conference highlights

A new era in large scale Passivhaus

Speakers from across the industry shared their thoughts and experiences on the drivers and benefits for delivering Passivhaus housing at an exciting scale. Stephen O'Shea, head of sustainability at Cairn Homes, discussed how the company is now firmly at the "Passivhaus party", and are now embracing the standard as a way of bringing in really meaningful change to this sector of the industry.

UK + IRL Passivhaus Conference 2025 | Image credit: PHT

We need to be acting at scale. Yes, everybody needs to do what they can, but for those of us in positions where we can act at scale, the onus is on us to do so. It has to be for the masses. It has to be about the just transition, we have to be focusing our efforts on the people who most need it in our society.

Stephen O'Shea, Cairn Homes

We saw how scale happens when successful projects become replicable. Fermanagh & Omagh District Council Leisure & Wellness Centre is proof that even the toughest project briefs can deliver outstanding Passivhaus performance if they follow the lessons learned of successful early Passivhaus swimming pools.

The design team at DAERA College discussed pushing the Passivhaus Premium boundaries with their ambitious Greenmount and Loughry campuses. Jonathan Greig of Hamilton Architects explained how the project promoted a highly collaborative working environment. Passivhaus principles were effectively communicated and integrated into the design process from the beginning, for example:

Form factor and orientation were a key consideration from a Passivhaus perspective.
Sketches and models were exchanged within the team, and preliminary PHPP testing was undertaken by our Passivhaus designer.
The required scientific Passivhaus parameters were embodied within the concept design
Spatial parameters for thermal elements were developed based on the Passivhaus 'fabric first' approach.
The fenestration strategy was constantly refined to assess the balance between solar heat gains and heat loss through the triple glazed windows.

The 'campuses of the future' project truly is a masterclass in replicable, large-scale campus strategy. It is a project that highlights that all the excuses in the market not to do Passivhaus, have now gone.

Collaborative working wins out

With over 50 speakers across two dynamic days, a range of perspectives demonstrated the power of collaboration in action. The event showcased what is possible when clients, design teams, contractors and policy makers work together to deliver Passivhaus.

Trent View College demonstrated what was possible when a team truly commits to Passivhaus. Collaborating with the wider project team from project inception allowed for early consideration and planning of complex build elements, optimal construction materials and ensured cost-effective project delivery.

The team at BE-ST introduced the step-by-step EnerPHit of Scotland’s National Retrofit Centre (SNRC). Supported by the Scottish Government’s Public Sector Heat Decarbonisation Fund, this collaboration showcased how large-scale estates can decarbonise incrementally, providing a practical template for other public bodies. Financial forecasting, strategic phasing, and open dialogue with funders were essential to maintaining momentum and outcomes in a fast-changing market.

Collaborative working is pushing Passivhaus projects into the mainstream, and quickly setting the standard as a new baseline for the future.

Science based solutions

One message was constant throughout the many projects - Passivhaus works. It is an evidence-backed, proven solution to industry wide problems such as poor constrution quality, high building energy demand and long term user health and wellbeing.

All of the inspiring projects over the two days demonstrated that Passivhaus was chosen as the most rigorous and internationally recognised route to deliver buildings that are low-energy, resilient to climate extremes and healthy for users. This was expertly demonstrated during the eye-opening Portmarnock Drumnigh Oaks Development presentation, where we were given a stark reminder of the benefits of installing an high-quality MVHR system.

The team in Ballymore were asking how much better is the air quality in a Passivhaus? So, we looked at how much toxic fumes can be built up in house through volatile organic compounds and particles in the air. If you break it down to a cigarette, you have the equivalent health risks of smoking of around 1000, 1500 cigarettes a year as a byproduct of living in a house. I think if you told anyone that their kids were living in that environment, they'd be kind of shocked.

Charlie Conlan, Ballymore

Standout Passivhaus projects leading the way

From transformative college developments and community centred projects to successful residential retrofits, the inspiring lineup of projects showcased how rigorous design, innovation and collaboration can turn climate ambition into measurable action. Early commitment to delivering Passivhaus was highlighted as the essential foundation for success in each of these impressive projects, each showcasing how the standard is being adopted throughout the industry.

Technical tours

The popular Passivhaus Masterclass on the 7th October offered attendees the opportunity to visit the case study in real life. As Queen’s University Belfast’s first Passivhaus‐certified student living tower, Weavers’ Hall Student Accommodation is shaping up to become an impressive landmark in the city.

Those lucky enough to secure a spot on the tour were able to discuss with the delivery team the many challenges and lessons learned they addressed while constructing the cities newest Passivhaus success. Topics included increased number and complexity of thermal bridge details, the impact of higher performance requirements causing potential budgetary pressures and the higher risk of installation errors on such a large development.

The tour offered a valuable first hand experience of large and complex Passivhaus construction in progress at scale. Attendees discovered procurement lessons, critical junctions, and airtightness techniques live at Belfast's Passivhaus giant.

UK & IRL Passivhaus Conference 2025 | Masterclass tour of Weavers Hall | Image credit: PHAI PHT

We couldn't do it without you

So, what was our takeaway from the day? The future is looking bright. Not only in terms of successful, certified build projects, but to in terms of driving new and dynamic Passivhaus visions forward. We have exciting times ahead and we can't wait to update you next year.

UK & IRL Passivhaus Conference 2025 | PHT PHAI Team | Image credit: PHAI PHT

We would also like to thank you, the Passivhaus community, who's continued collaboration ensures that Passivhaus is promoted as the built environment's best solution to our changing climate. This was the first co-hosted Passivhaus Conference - a truly collaborative effort between the Passivhaus Trust and the Passive House Association of Ireland. We would like to extend our thanks across the teams, who's enthusiasm and passion helped to make this our most successful conference to date.

We'd also like to extend a huge thank you to all the delegates who attended the UK + IRL Passivhaus Conference 2025 and to all our conference sponsors, speakers and site tour hosts. We can't wait to see you again in 2026!