Ireland’s largest homebuilder commits to Passivhaus

Cairn Homes, Ireland’s largest house builder, has announced a bold commitment to Passivhaus standards, starting with over 1,700 homes already underway.

Why Passivhaus?

For residents, Passivhaus homes mean healthier, quieter, and more comfortable living environments, with substantially lower running costs. Cairn expects to reduce the heat energy demand of its homes by more than half, with residents predicted to save around 41% on annual energy bills. A powerful selling point at a time of energy price volatility and cost-of-living pressures.

For Cairn, the quality assurance required for certification reduces defects and costly remedial works. Passivhaus also offers a strong market differentiator in a housing market where sustainability is becoming mainstream. Importantly, Cairn is absorbing the additional construction costs, showing that Passivhaus is both commercially viable and aligned with its long-term business strategy.

Passivhaus provides huge direct benefits to our customers... It's not just about the carbon reduction. This is about the people living in our homes. It's about the money in their pockets. It's about the comfort in their homes. It's about fresh air. It's about energy poverty. It's about all of those really tangible benefits.

Stephen O'Shea, Head of Sustainable Construction, Carin Homes

Small changes – big carbon savings

Passivhaus apartments Pipers Square, Dublin. Image credit: Cairn Homes

Beyond comfort and cost, Passivhaus also supports Cairn’s science-based targets to decarbonise its business by 2030.

Currently, Cairn applies a 39% penalty to its carbon footprint reporting for non-Passivhaus homes, recognising the performance gap between design and real-world energy use. With precise PHPP modelling and quality assurance, Passivhaus significantly reduces this gap.

While reducing embodied carbon requires a complete overhaul of supply chains, the operational carbon savings achievable with Passivhaus come from a few key adjustments, making it a practical and cost-effective way to lower emissions.

By upskilling its existing workforce, Cairn demonstrates that incremental changes can deliver substantial results. Across four developments, the adoption of Passivhaus will save an estimated 75,000 TCO2 (Total Carbon Dioxide), which is the equivalent of flying 68 million air miles, according to Gavin Whelan, Cairn Homes’ Director of Construction & Operations.

Gavin Whelan, Emma Osmundsen and Stephen O’Shea, at the launch of Cairn's Position Paper

Read more in Cairn's position paper Passive House – Sustainable Living Spaces.

Rolling out at scale

Cairn’s commitment represents an unprecedented scale for Passivhaus delivery in both Ireland and internationally. Four major apartment schemes are now under construction across Dublin:

Pipers Square, Charlestown – 598 apartments, set to be Europe’s largest Passivhaus development.
Cooper Square, Seven Mills – 607 apartments.
Whitehaven, Santry – 255 apartments.
Niven Oaks, Santry – 303 apartments.

Traditionally, Passivhaus projects in Ireland have been measured in the dozens, not thousands. Delivering at this scale demands a shift in skills and culture. Cairn has committed significant resources to training, with senior technical staff undertaking the Passivhaus Designer course and bespoke training programmes being developed for site supervisors.

Don’t get left behind!

Cairn Homes isn't the only developer recognising the value of Passivhaus. More and more industry leaders are seeing the commercial benefits of building to this standard. Stay competitive in the market and explore the business case for Passivhaus at the UK & Ireland Passivhaus Conference 2025. Join Stephen O’Shea, Head of Sustainable Construction on 8 October 2025 to learn more about how Cairn Homes is taking Passivhaus mainstream.