Large-scale Passive House Institute LEB project for Belfast housebuilder
A pioneering housing development in Belfast, Northern Ireland targeting the Passive House Institute Low Energy Building (PHI LEB) standard is nearing 50% completion. Once completed, the Lancaster Park 219-home development by Fraser Millar will be the largest privately-funded residential scheme certified to the PHI LEB standards in the UK and Ireland.
The homes, which include a mix of 3-4 bed semi-detached and detached houses, are for private sale through Simon Brien Estate Agents and A M Property Management. PHT member Mosart has undertaken the certification on the project. All the homes are aiming for PHI LEB (Passive House Institute Low Energy Building) certification. They use air source heat pumps for heating and hot water, resulting in an EPC ‘A’ rating.
Key stats
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Consumer perspective: Why buyers want low-energy homes
“Over the last decade, there has been a sea change in what people expect from their homes. Buyers now value energy efficiency, low running costs and environmental credentials when choosing a home.”– Simon Brien, Simon Brien Estate Agents
With energy costs and climate change at the forefront of public consciousness, Lancaster Park reflects a growing buyer demand for sustainable homes that offer both financial and environmental resilience. The first phase of the Lancaster Park project exceeded all expectations by selling out in its entirety within one hour of going on the market, reinforcing the consumer appetite for high-performance homes.
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Extensive research has shown us that the modern buyer wants homes to be healthy, future-proof and considerate to the eco challenges of sustainable development. We have worked closely with the design criteria alongside experts both in Germany and across the globe to ensure these homes meet the Passive House Institute LEB standard. David Millar, Director, Fraser Millar |
Construction
The homes are being constructed using a 184mm timber frame kit with a brick façade. The decision to use a timber frame construction was initially led by the constraints on brick supply immediately after the Coronavirus lockdown and also because of the sustainability benefits of the supply chain of the timber used by the kit supplier.
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Fraser Millar has shown with Lancaster Park that housing in large family developments can meet customer expectations with regards to aesthetic appeal and design and still offer the benefits of true low energy building.
John Carrigan, Managing Director, Fraser Millar |
U-values |
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Roof: 0.9 W/m2K |
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Wall: 0.15 W/m2K |
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Floor: 0.12 W/m2K |
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Building performance
Energy performance |
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Designed (average) |
Actual (average) |
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Airtightness n50 |
1.0 @ 50 Pa |
0.5 @ 50 Pa |
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Space Heating Demand |
30 kWh/m².a |
23 kWh/m².a |
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Heating Load |
15 W/m² |
13 W/m² |
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Primary Energy Renewable (PER) Demand |
75 kWh/m².a |
51 kWh/m².a |
Services
Heating & ventilation: The developers aimed to eradicate fossil fuel from the development, so a combined compact ASHP/ MVHR unit was specified for the project, with heating supplemented by a small number electric radiators. MVHR systems were largely unknown in the Northern Ireland market at the time and the developers opted for a compact combined ASHP/MVHR unit rather than stand-alone MVHR system, to save space and to reduce the urge by homeowners to turn off their MVHR.
Renewables: Phase 2 onwards saw the introduction of a 3.9kW Solar PV panel system supplied as standard.
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In this flagship development, we have entirely eradicated the reliance on fossil fuels. Instead, we have utilised the very latest in technology to keep our properties warm all year round whilst removing the worry of ever-fluctuating fuel prices. David Millar, Director, Fraser Millar |
Challenges & lessons learned
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Planning approval: The project had already received planning permission 4 years before the decision was made to move to Passive House Institute Low Energy Building standard certification. Fraser Millar effectively turned a previously-approved scheme, that was designed for typical Northern Ireland building code construction at its inception, into a successful certified project.
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Airtightness: Achieving the airtightness maximum of 1.0 ACH for PHI LEB was initially challenging on site and part of a steep learning curve, but as Passivhaus training was extended and delivered, achieving the PHI LEB requirements is no longer a concern, and the contractors now report being disappointed if airtightness levels exceeds 0.6 ACH.
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Monitoring: Fraser Millar undertakes electricity consumption monitoring for each house each month, giving the opportunity to compare real life performance versus predicted usage. The monitoring is delivering encouraging results, with the houses reporting approximately 5% less energy use than the PHPP prediction, on average.
Developer’s viewI researched and found that the best way to control fuel bills is to build low-energy housing, the gold standard of which is Passivhaus. Homes in the UK are a significant source of energy demand and greenhouse gas. The Passivhaus standard reduces both. That means low heating bills, more stable indoor temperatures, and improved indoor air quality for people. When you make it possible for people to live where they don’t have these huge raises and swings in fuel prices – and therefore fuel poverty – you end up designing a house that is very low energy. The whole concept is to not need to heat it very much because the heat stays there. Geographic location, form factor, and the orientation of individual houses in a 219-house development influenced the developers’ decision not to pursue the full Passivhaus standard. The extra costs involved would not be recoverable in the sale price, and the return from energy price savings would take too long to bridge the cost increase. I took the idea to the company owners, who were immediately convinced and agreed to adopt Passive House Institute Low Energy Building standards for the Lancaster Park development. John Carrigan, Managing Director, Fraser Millar |
Lancaster Park has already inspired Fraser Millar to extend its PHI LEB commitment across future projects, including:
- 84 homes in Carryduff
- 6 homes in Lisbane
As Managing Director John Carrigan explains: “Once you build to this standard, it’s unthinkable to go back to typical building practices. What is seen cannot be unseen.”
Key team
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Lancaster Park is a UK market first for private developments adopting the Passivhaus methodology. Hear Iain Stewart from Formative Architects outlining the project as a keynote case study at the 2025 Passivhaus Conference on Wednesday 8 October.
Further information
2021 UK Passivhaus Conference: Delivering net zero through Passivhaus
ITV News: Belfast man recognised as ‘Everyday Climate Hero’ for building low-energy homes
Having witnessed homeowners experience the never-ending upswings and downswings of fossil fuel costs affecting a family’s disposable income from time to time, Managing Director of Fraser Millar, John Carrigan, sought to reduce the impact of this by building homes that made the costs of heating and hot water supply more predictable and affordable. Through thorough research, Passive house principles stood head and shoulders above all in achieving this goal.
Working closely with architect Iain Stewart and PHPP Designer Garrett Quinn, Fraser Millar turned a previously approved scheme, that was not designed at inception as Passive house, into a very successful Passive LEB project.
A lack in Northern Ireland, of skilled, passive house experienced contractors resulted in a very steep learning curve with initial houses struggling to meet the air tightness maximum of 1 ACH, we are now proud to say that this is no longer a concern, and we now get very disappointed if our airtightness exceeds 0.6 ACH.
We also understand that we are the only developers in Northern Ireland that monitors and records electricity consumption per house each month. This affords us the opportunity to compare real life performance versus predicted usage. Results are very encouraging.
Clearly, what is seen can’t be unseen. It would be unthinkable to return to normal “typical” building standards. To that end Fraser Millar have launched its 2nd and 3rd Passive house developments. 84 family homes in Carryduff, with the benefit of full hot and cold air conditioning and a 6 house development in Lisbane.
1st September 2025
Get involved with the UK Passivhaus community
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