A highly sustainable housing development in the centre of Salford has set a new standard for healthy, high quality affordable housing, complete with Passivhaus certification. Roseanne Field takes an in-depth look behind the facade.

Located in the heart of Salford, historic Chapel Street is part of a wider area that’s undergoing a significant regeneration. A £1bn masterplan spanning 50 acres is underway to transform the area and ultimately benefit the city’s residents, who are collectively some of the most challenged in the UK. Salford itself is the 18th most deprived area in the UK, with the highest mortality rate from lung disease. The regeneration is the result of a joint venture known as English Cities Fund (ECF), a partnership between Homes England, Legal & General, and Muse.

This regeneration includes Greenhaus, a 96-unit development of affordable homes built to very high sustainability standards. The project aims to “bridge a gap in the housing sector for affordable, high specification living,” explains executive director of assets, growth and sustainability at Salix Homes, Liam Turner. 

The development has achieved Passivhaus Classic certification – and is thought to be the largest project of its kind to do so in the north west. ECF was supported in delivering the project by Salford City Council; Salix Homes is the development’s housing association partner, with the homes built by lead contractor Eric Wright Construction. 

Finance for the multi-million pound development was secured by Salix Homes, who obtained funding from NatWest bank alongside grants from Homes England and Greater Manchester Combined Authority (GMCA). It fits into GMCA’s ambitious strategy to increase the number of affordable, net zero housing in the Greater Manchester area. 

Addressing local needs

Greenhaus embodies a shared commitment to address housing shortages and improve both environmental standards and living standards for local people. “For Salix Homes, Greenhaus represents the future of affordable and social housing,” explains Turner. “It demonstrates what can be achieved through effective partnership working and a shared desire to create cleaner, greener, and healthier homes that are fit for the future and which won’t need retrofitting.” 

Salix Homes owns 8,000 properties across Salford, with the majority of its customers in receipt of welfare benefits. “The new homes at Greenhaus help reduce fuel poverty for residents, with
the monthly cost of heating and hot water at around 68% less than a typical scheme built to current Building Regulations,” explains Muse project director Simon Hourihan. 

Achieving Passivhaus certification not only helps residents from an affordability perspective, but also offers a range of health benefits which in turn “can reduce the impact on the NHS and the costs associated with illness related to poor quality housing and health inequality,” Hourihan continues. Thanks to the airtightness, thermal comfort and improved ventilation of Passivhaus properties, residents are better protected against airborne pollutants, the risk of illness associated with living in a cold home is reduced, as is the risk of damp, mould and condensation. 

Greenhaus comprises a mix of one and two bedroom homes, including four accessible apartments on the ground floor. The homes are mixed tenures – 11 are for social rent, 13 for affordable rent and the remaining 72 available as part of the Rent to Buy scheme. 

The decision on how to split the tenures was taken carefully. “To ensure the development would meet the local housing need, extensive consultation was undertaken with Salford City Council,” explains Alison Haigh, Greenhouse project leader and certified Passivhaus consultant at Buttress Architects who designed the building. “The provision of affordable homes was and is vitally important to the community, and the ambition for Greenhaus to be the largest Passivhaus affordable housing scheme in the north west was to address this as part of the answer to bridging the gap in the housing sector for both affordable and sustainable homes.”

Complementary design

Much of the development’s design was influenced by the surrounding area, as well as the Passivhaus certification target. Located in what Haigh describes as a “prominent” location on Chapel Street, Greenhaus sits opposite the Grade II* listed Salford Cathedral. “Key to the design intent, therefore, was a desire to reinforce the architectural setting and the sense of place of this part of Chapel Street and respect the development’s position across from this important part of Salford’s civic life and urban history,” she explains. The site also presented some practical challenges – in particular underground services that would be uneconomic to remove meant the buildable site footprint was constrained. 

Despite the tricky location, ECF’s good working relationship with Salford City Council meant the planning process went smoothly, with the partnership having “the full support and co-operation of Salford City Council planning team throughout all stages,” explains Turner. Planning permission was granted in November 2021, and with all the necessary funding secured soon after construction began two months later in January 2022. The development was completed in February 2024, with both the first residents moving in and Passivhaus certification being received in March 2024.

In the end, the final design “successfully resolved these distinct challenges in a form that reinforces the connection with the Cathedral and its presence on one of the key arterial routes into Manchester,” Haigh says. The final material choices were heavily inspired by the architecture of Chapel Street. “High quality brickwork was selected to match the materiality of nearby buildings, while the buff colour was specifically chosen to harmonise with the cathedral, respecting its historic and landmark setting,” she continues. 

As well as materiality, the cathedral also had an impact on the design of Greenhaus’ volumes. The development comprises two blocks of six and eight storeys high, forming an L-shape that also creates a new landscaped public area which faces the cathedral. “The primary drivers behind the massing were to recognise the prominence of the cathedral and provide a public space opposite to enjoy it, together with a need to bring forward an efficient building form and massing to support Passivhaus best practice,” explains Haigh. “Form and mass are critical for a multi-apartment Passivhaus building as maximising the built volume in relation to surface area drives thermal efficiencies.” 

The two building entrances are connected via a spacious central lobby – a deliberate design choice to promote community interaction. All the apartments benefit from open-plan living spaces and Juliet balconies, offering residents impressive views as well as creating a “strong visual connection to the outside.” Externally extensive soft landscaping was included to provide wildlife habitats and ecological benefits. There is also parking at the rear of the building, including EV charging stations. 

Pushing towards Passivhaus

Aside from the local area impacting the design, many of the choices were dictated by the aim to achieve Passivhaus certification, such as the buildings’ orientation, and form factor (the efficiency generated by the buildings’ shape). “Detailed design elements were highly driven by the technical Passivhaus design standard requirements in terms of thermal performance, airtightness, thermal bridging and the performance of MEP equipment,” explains Hourihan. 

The project utilised several processes which Haigh says “broke ground for residential Passivhaus construction.” One such example is the steel framing system (SFS) used in the development’s structural external envelope. Previous certified schemes have used concrete block, but SFS is much quicker to install. “It imposes less weight on the structure and can be used in conjunction with mass climbers, reducing the construction programme and the cost,” Haigh says. 

The decision to aim for certification was made very early on in the project by Salix Homes and Muse, which meant the design was developed with this goal in mind from the outset. Despite the build cost being higher, Turner says “we considered the long term savings to be made on repairs and maintenance or complex and expensive retrofit solutions, as well as the financial and health benefits for residents.” 

To meet the rigorous requirements for certification, several key features were incorporated. They installed air source heat pumps and airtightness was “carefully improved to reduce heat loss, while thermal bridging was meticulously addressed to prevent unwanted heat transfer,” explains Hourihan. Gaps larger than 3 mm in the envelope (for example at junction points or where
vents penetrate the structure) were not permitted.

High performance triple glazed windows were used to minimise energy loss and improve insulation, along with the high levels of insulation installed. Efficient appliances and upgraded ventilation systems were also utilised. “Together, these elements work to create a more sustainable, comfortable, and energy efficient living environment,” Hourihan says. 

Hourihan estimates that the total added cost of these measures was around the £2m mark, adding 10% to the total project cost. Thankfully, he adds, this was offset by the financial support received by Homes England and GMCA, as well as the money Salix Homes was investing in itself. 

The process and steps to be taken in order to achieve certification was a challenge of its own. As well as the project requiring a Passivhaus designer or consultant, an independent certifier guided and oversaw the entire process. “The certifier conducts an initial review at RIBA Stage 3, a design review at RIBA Stage 4, and a construction review at RIBA Stage 5, which includes regular
site inspections and quality assurance,” Haigh explains. 

In order to ensure this process ran smoothly, close collaboration with main contractor Eric Wright Construction was critical. The team undertook an airtightness test on a mock-up which helped them identify any potential issues before construction began, thus reducing the risk of potential costly corrections. “Detailed planning ensured that the final ‘As Built’ assessment and certification aligned seamlessly with the practical completion,” says Haigh. 

Despite the additional measures required by the stringent certification process, Haigh says it’s key in order to verify the building meets the energy performance targets outlined initially. The meticulous attention to detail during construction also mitigates the likelihood of damage to the building fabric, helping futureproof the building generally. Luckily, the contractor “embraced these standards, implementing strong quality control measures,” says Hourihan. 

The high sustainability and performance standards proved to be a challenge generally, with Hourihan describing a “limited level of experience within the supply chain” as another key obstacle encountered. However, he says: “To address this, we engaged with contractors early in the process and collaborated with all stakeholders from the outset, ensuring a shared commitment to meeting project standards.”  

Collaborating with stakeholders throughout the process was also essential from a risk management perspective. “Greenhaus had contractual obligations to deliver a Passivhaus certified, high quality development,” says Hourihan. “Understanding these obligations and associated risks required careful planning to ensure all contractual standards were met and risks were mitigated.” 

Collaboration in general proved to be essential in the success of the project, particularly given it was the first Passivhaus project for Salix Homes, Muse and Buttress. “It was a learning curve for us all, and collaboration and communication between the partners has been key throughout,” Turner says.

“A key factor in the project’s success was the engagement with a project team that fully understood the demands of Passivhaus accreditation and were committed to its successful delivery,” adds Haigh. “In particular Eric Wright Construction, working with the design team, happily established quality control procedures that minimised risk.” This included the testing of prototypes and the inspection and testing of building work as it made progress.

Although the project was an overwhelming success, that’s not to say there weren’t lessons learned during it. “A critical lesson was the importance of managing costs effectively and utilising Passivhaus Planning Package (PHPP) as a design tool to evaluate various options throughout the project,” Hourihan says. Another lesson, he says, was the importance of precision construction,
and the need to manage tolerances carefully, emphasising that the need for tight quality control of work shouldn’t be underestimated.

He believes the team gained “valuable insights” into how best to deliver sustainability targets at this level. “Projects like this can be achieved primarily with standard technologies, although early engagement with the supply chain is essential due to limited availability of certain specialised materials,” he says. 

Looking to the future

The team behind Greenhaus believe it’s proof of what can be achieved, even on projects of this size and tenure, with Hourihan saying it sets “an important example”. However, he also acknowledges the increased cost of delivering such a project is a major obstacle preventing others from following suit, as well as the general lack of knowledge and understanding around the “rigorous design standards and elevated construction quality required.” He asserts: “By demonstrating that high sustainability targets are achievable on a large scale, Greenhaus serves as a model.” 

Turner agrees that cost is a barrier, but argues it “makes strong business sense” when factoring in longer-term savings on repairs and maintenance, and potential retrofits. He also believes the financial and health benefits for residents make a strong case for pursuing Passivhaus certification. “In the context of the cost of living crisis, a shortage of affordable housing, and the urgent need to address climate challenges, Greenhaus demonstrates what’s possible.”

The team’s experience on Greenhaus has already paved the way for a second Passivhaus project – a sister development named Willohaus which will deliver 100 affordable apartments. Planning permission has also been granted for a third scheme for Salix Homes – a 69 unit “independent living scheme” for over 55s. 

Impact on residents

Ensuring the success of a Passivhaus project ultimately relies on residents using the homes and their features correctly, which is why Salix Homes introduced a “careful education and monitoring process,” as well as having a specialist support team. Residents receive an in-depth user guide and videos to help them understand their home and ensure it performs as intended. “We have also installed technology to remotely monitor the air quality and energy usage, and we’re monitoring the data and repairs and maintenance expenditure alongside non-Passivhaus developments to track the long-term benefits,” Turner adds. 

Taking things one step further, the company is also working with sustainability specialists Max Fordham to track the health of residents, to gain further insight into the benefits of a Passivhaus property. 

Turner says the project has been “life-changing” for some residents, with some previously living in conditions which were affecting both their mental and physical health. “Seeing the journey some of our new residents have been on really highlights the pressing need for more social and affordable housing,” he says. 

The project has received an enormous amount of interest from the housing and construction industries, as well as government officials, and the team believes what has been achieved at Greenhaus should set a benchmark for future developments. “High spec homes with the energy saving credentials of Greenhaus are uncommon in the social housing sector,” Turner concludes. “It represents a new era of high quality, sustainable and affordable homes which are better for the environment, support carbon reduction targets, and help reduce fuel poverty for residents.”