On a single day in Dublin, Professor Wolfgang Feist formally opened three large-scale Passive House schemes across the city. More than 850 homes. Three approved housing bodies and state agencies. One unmistakable message: Passive House in Ireland is no longer a niche.
Professor Feist is the physicist who founded the Passive House Institute and, in 1991, moved into the world’s first certified Passive House in Darmstadt. For over three decades, the standard he developed has been the most rigorous measure of building energy performance available to designers, developers, and certifiers. When he travels to formally open a scheme, it is not a courtesy visit. It is a statement about significance.
His visit to Dublin marked the certification of three large-scale developments built by Cairn Homes: Whitehaven in Santry, Pipers Square in Charlestown, and Cooper Square at Seven Mills. Mosart’s architectural team has played a direct role in all three.
Three Schemes. One Shift.
Whitehaven, Santry is a 255-home development delivered for Tuath Housing Association. All homes have been completed and handed over to residents. Mosart acted as Passivhaus designers on the scheme and continues to conduct post-occupancy evaluation, monitoring how the buildings perform once families are actually living in them. Real data, real conditions, not theoretical outputs.
Pipers Square, Charlestown is a 598-unit scheme developed in partnership with Respond Housing Association and Fingal County Council. It is set to become one of the largest Passive House housing schemes in Europe. Mosart served as Passivhaus designers here too, working through the technical complexity of delivering the standard at a scale that, until recently, very few practices anywhere in the world had attempted. RTÉ
Cooper Square, Seven Mills is a 608-unit scheme developed by the Land Development Agency, the state body established to deliver housing on public land. Mosart acted as Passivhaus Certifiers on this project, providing the independent technical verification that confirms the buildings meet the PHI standard.
Across the three sites, over 850 homes have been completed or handed over, with Passive House units now accounting for one-third of Cairn’s total output. Passivehouseplus
Why This Matters Beyond the Numbers
The story of Passive House in Ireland has, until recently, been told mostly through one-off houses: well-resourced clients, progressive architects, projects that could absorb the learning curve. That story was important. It built the knowledge base, the supply chain, and the professional confidence that made what happened this week possible. But it also created a perception that needed correcting.
Passive House was for people who could afford it. A premium product for a small market.
What Feist’s visit to Dublin demonstrates is that this perception is now demonstrably wrong. The three schemes he opened are social and affordable housing. They were delivered through approved housing bodies and a state agency. They are homes for families who are, in many cases, already managing tight household budgets. The standard that once seemed aspirational has been delivered at scale, by a mainstream housebuilder, for the people who stand to benefit from it most.
The comfort and energy performance of a Passive House are not abstractions for residents living in these homes. Passive homes are designed to maintain a constant temperature of 20 degrees, 24 hours a day, and provide a constant supply of filtered, fresh air, rather than the conventional model of intermittent heating for a few hours per day. Cairn estimates that heating bills in its Passive House schemes run up to 40% lower than in an average new build. For a household already under pressure from energy costs, the difference is immediate and real. RTÉ
Post-Occupancy: The Work After Handover
One of the less-discussed aspects of Mosart’s involvement in Whitehaven is what happens after residents move in.
Post-occupancy evaluation is the practice of monitoring how a building performs in real use, comparing actual energy consumption, indoor air quality, and comfort data against the predictions made at design stage. It is the only honest way to know whether a Passive House delivers what it promises, and it is the work that turns a well-designed building into evidence.
Mosart’s architectural team is conducting this evaluation at Whitehaven. The insights from a scheme of this scale, occupied by a diverse range of households, will inform how future large-scale Passive House projects are designed, specified, and operated across Ireland. That is not a small thing. It is the kind of feedback loop that moves an industry forward.
What Comes Next
Professor Feist noted that the Passive House standard offers a proven approach to achieving very low energy demand while ensuring excellent indoor comfort, and that this relevance has only sharpened given the energy price pressures households across Europe continue to face. He is right. And Ireland is now producing the evidence at scale. Passivehouseplus
The professionals who designed and delivered these schemes have built competence that does not disappear. The supply chain that supported them is now experienced. The approved housing bodies and state agencies that commissioned this work understand what it delivers.
Passive House in Ireland is no longer waiting for permission to go mainstream. It has.
Mosart Group has been a Passive House and sustainable building practice since 1993. We provide Passivhaus design services for large-scale residential and commercial projects across Ireland and the UK, and Passivhaus certification, energy modelling, and post-occupancy evaluation. If you are considering Passive House on your next project, get in touch.