Yr Hafan, Lifecycle Assessment

Drew Barker
Posted January 04, 2024

Yr Hafan, our collective housing scheme for families at risk of homeless in Cardiff, has been officially certified to Passivhaus Plus standard by the Passivhaus Institut in Germany. We believe it’s the first relocatable residential modular housing scheme in Europe (and possibly the world) to achieve the rigorous energy efficiency standard.

As part of the project, we commissioned data analyst Cercula to conduct a full lifecycle assessment over a 60-year period. According to Cercula’s analysis, the whole life carbon impact of the scheme is 1,460 tonnes. This is estimated to be 78% lower than a traditional masonry build[1], resulting in a saving of around 5,189 tonnes of carbon. Yr Hafan is energy-negative as designed, with an average energy usage of -39kWh/m2/y, and a net zero carbon operational performance rating. The embodied carbon, calculated at 242 kgCO2e/m2, is significantly below the RIBA 2030 Challenge target of <750 kgCO2e/m2.

[1] The traditional masonry baseline was generated by RICS chartered quantity surveyors, Derek Gough Associates.

Another photo of our award-winning modular homes in Cardiff

Somewhat ironically, this ‘fossil fuel-free’ development has been built on the site of a former gasworks in Grangetown – we felt that was very symbolic in light of the UK’s continued reliance on gas for domestic heating. Officially rated ‘Net Zero’ for operational carbon, Yr Hafan consists of forty-eight volumetric modular 1, 2 and 3-bedroom apartments, and two additional administrative/communal blocks, containing offices, a training room, a training kitchen, a medical office and even a crèche.

Below is a graphical summary of the LCA findings.

As you can see, lifecycle cost savings are estimated to reach £17 million over a 60-year timespan, when compared to a like-for-like traditional masonry build with average energy consumption.

Yr Hafan provides high quality, energy efficient, comfortable and sustainable accommodation for families at risk of homelessness, together with extensive wraparound support services.

Climate change and carbon were at the heart of Cardiff Council’s Local Development Plan, alongside strategies to end homelessness and tackle fuel poverty. Passivhaus Plus was specified to improve energy efficiency, raise living standards and act as a pathway to achieve net zero for operational carbon.

The homes were rigorously tested before they left our factory and again once they were in situ. We always build our homes to Passivhaus standard, so they must achieve an air test result of <0.6ACH@50pa before they are approved for despatch.

Working in Partnership with Cardiff Council

Commenting on the scheme, Lynda Thorne, Cabinet Member for Housing and Communities at Cardiff Council, said: “What a wonderful facility Yr Hafan is, a real haven for families during a difficult time. As well as the new flats, the Caban Yr Hafan is a focal point on the site, a mini community centre for residents where they can access visiting health services, Into Work support, Adult Learning opportunities, or just come together with neighbours to use the community facilities.

“Nobody wants to be living in temporary accommodation, but we’ve had some great feedback from the families staying at the centre, both in terms of quality of the flats and the support they receive from our staff there. And, of course, the beauty of this type of build means we can move the units to other locations across the city in the future, if necessary.”

Passivhaus Plus and Modern Methods of Construction

The scheme at Yr Hafan is notable for several reasons. Firstly, Passivhaus Plus is a relatively new standard that recognises the production of renewable energy by passive buildings. It combines the ‘Fabric First’ philosophy with the 5 Principles of Passivhaus[2] and onsite renewable energy to achieve net zero for operational carbon. As a result, the homes at Yr Hafan don’t just save energy – they generate their own. In fact, they produce enough energy to power the homes throughout the year, effectively transforming Yr Hafan into a Passivhaus Powerhouse. This approach significantly reduces heating bills and serves as a highly effective strategy to prevent vulnerable people from falling into fuel poverty.

Definition: The ‘Passivhaus Plus’ standard is a new certification category designed to recognise the production of onsite renewable energy by passive buildings. It requires a minimum of 60k kWh/m2/yr of renewable energy generation, along with a maximum renewable primary (PER) energy demand of 45 kWh/m2/yr.

Passive House Plus Magazine, Glossary

Secondly, the entire scheme was constructed using Modern Methods of Construction (MMC). Yr Hafan was designed in the PHPP (Passivhaus Planning Package) and constructed using our ‘Passivhaus-certified’ timber frame build system at our offsite manufacturing facility in Norwich, Norfolk. The homes were then transported to site by road and craned into position.

Thirdly, the entire scheme is fully demountable and relocatable. This gives Cardiff Council the ability to respond to changing housing needs in the city, without any need to demolish and rebuild – both of which are carbon intensive. Ron Beattie, founder and managing director of Beattie Passive, said: “Cardiff Council declared a climate emergency in 2019 and has pledged to become carbon neutral by 2030. We’re very proud of what we’ve accomplished together so far, not just in terms of the environmental impact of achieving net zero, but also the enormous social benefits of the scheme for everyone involved. Yr Hafan really does show what can be achieved using MMC.”

“The homes are extremely energy efficient, healthy, sustainable, affordable to run, and comfortable to live in. As the saying goes, the cheapest and most renewable energy is always the energy you don’t use. That’s the beauty of Passivhaus and the Fabric First approach – the energy demand is so low that simply fitting PV panels on the roof spaces was enough to achieve net zero for operational carbon.”

It’s no secret that the UK is in the midst of a chronic housing crisis and rates of homelessness are on the rise. Ron believes that schemes like Yr Hafan can ease the housing crisis, provide homes for the homeless, alleviate fuel poverty and reduce the reliance on private accommodation, such as hotels and B&Bs, to house refugees, migrants and asylum seekers[3]. “The Home Office recently disclosed that the government spends around £7 million every day on private accommodation.” said Ron. “By investing in our modular homes, local authorities and other housing providers end up with a long-term asset that meets their needs in terms of affordability, speed, environmental sustainability and low energy costs.

“The carbon savings are enormous and the lifecycle cost savings for Yr Hafan are expected to exceed £17 million when compared to a like-for-like masonry build, with average energy consumption. Cercula also estimated that residents would save a considerable amount on their energy bills, and that was before the sharp rise in energy prices,” added Ron.

Building a Net Zero Future in Wales

We're working with Wates to deliver modular homes in Wales

We’re currently working in partnership with tier one contractor Wates Residential to manufacture an additional 78 net zero modular homes and a community centre to further extend the scheme.

The initial phase of the project is already well underway. We’re building 16 x 4-bedroom homes, 22 x 3-bedroom homes, 30 x 2-bedroom homes and 10 x 1-bedroom homes, at our factory in Norwich to be then transported to South Wales. In total, we’ll build 78 net zero modular homes and a community centre – all A-rated SAP and built to the stringent demands of the Passivhaus standard. This is the first phase of an ongoing large volumetric programme which will provide relocatable accommodation for Cardiff Council. To learn more about this scheme, visit our projects page.

[2] The principles of Passivhaus are 1. High quality insulation 2. Superior windows 3. Airtight construction 4. Heat recovery ventilation 5. Thermal bridge-free design [3] As defined by Amnesty International –