With the government committed to reaching ‘net zero’ greenhouse gas emissions by 2050 and more than two thirds of councils declaring a climate emergency, local authorities are facing a challenge – how to meet climate change targets whilst delivering urgently needed affordable homes for their residents.  

 

Working mainly within affordable housing, sustainability and social value have always been at the forefront of our projects. With the construction industry producing nearly half of carbon emissions in the UK[1], we are committed to taking urgent action to decarbonise the industry we work in. We have long practiced a ‘fabric-first’ approach to affordable sustainable housing, keeping the design simple and focusing on those elements that will make the greatest impact. This approach leads to better, more comfortable living conditions for residents, while reducing the building’s energy demand. Proposed changes to Part L and F through the Future Homes Standard will help to cement this fabric-first approach into regulations but with performance gap data, a 5.0 m3/(h.m2) air tightness requirement and optional MVHR, they still do not go far enough. In 2020, Good Homes Alliance published a paper that compared low energy building standards for new homes, with net zero (operational) outcome targets. The paper sought to illustrate how the choice of selecting a building standard affects the amount of renewable energy generation that is required to comply with a net zero operational outcome. It found that a building built to SAP standards was estimated to perform with a 60% gap, a figure that raises legitimate concerns with quality and assurance of our regulations. 

 

Widely considered the gold standard for the design and construction of comfortable, highly energy efficient buildings, Passivhaus standard sets performance targets that prioritise the building fabric. Certified projects are built with meticulous attention to detail and rigorous design and construction according to principles developed by the Passivhaus Institute in Germany. Unlike a typical UK Building Regulations and SAP standards home, Good Homes Alliance found that Passivhaus buildings didn’t suffer from a performance gap. Passivhaus produces efficient buildings and while this alone will not necessarily reach net zero carbon, it does dramatically reduce the amount of energy needed to heat and service houses. Teaming Passivhaus construction with relatively low levels of on-site renewable energy sources such as a heat pump and photovoltaic panels, makes genuinely zero carbon homes a reality. 

 

With our work rooted in affordable and social housing, we have long helped local authorities deliver aspirational homes on tight budgets. Increased costs related to Passivhaus can add an extra challenge to the already tight cost margins of local authority developments, but it is imperative that the long term social and financial value created by delivering healthy homes is considered. In comparison to a building regulations compliant home, Passivhaus schemes were reported as being 3-8% more expensive[2]. An uplift in the cost of the building fabric is partially offset by a reduction in building services and much of the current additional construction cost is allocated to contractors’ risk. As the industry adopts these methods as standard, and the perceived risk is managed, the hope is that the cost of Passivhaus will reduce even further. 

 

Developed across six sites, our project Ealing Housing is a first for the London Borough of Ealing, providing 134 Passivhaus new homes. At 73% affordable rent, the multi-unit schemes have been designed to reduce energy consumption, address fuel poverty and meet Ealing’s commitment to deliver net-zero carbon homes. The brownfield plots are rich in their context and range from infill sites to car parks. These redundant pieces of land are typical of those available to local authorities in and around London. Having successfully gained planning permission for all six sites in 2020, we believe that they showcase how this type of sustainable housing can be developed successfully throughout the city. 

 

With adaptations to suit the scale and context of each site the schemes, ranging from mid-rise blocks to terrace houses, all benefit from economies of scale with the buildings sharing a common material palette, architectural language and technical detailing. Early in the process, the design team worked with a Passivhaus consultant (Qoda) and cost consultant (Gleeds) to holistically develop the schemes and ensure the buildings were cost effective while also meeting the Passivhaus standard. A consolidated and homogeneous set of construction details, which will be rolled out across sites to reduce construction waste, time and money, were tested pre-planning with the PHPP to provide assurance to Ealing and tendering contractors. The buildings’ orientation and window design have been carefully considered to mitigate heat loss in winter and heat gain in summer while taking into account the constraints of complicated urban sites. To reduce energy demand, the building forms have remained as simple as possible, with very high levels of insulation, high performance windows and excellent air tightness. A mechanical ventilation system with highly efficient heat recovery has been specified to work alongside natural purge ventilation with an option for exposed concrete soffits to enhance the thermal stability inside the homes, assist natural ventilation and daylight through higher floor to ceiling heights, and reduce the cost of installing plasterboard ceilings in habitable rooms. 

 

At Bell Phillips we all share a passion – to deliver aspirational designs that make a positive impact on people’s lives. With the climate and housing crisis worsening, it is our duty to ensure that our designs are as sustainable to build and live in as possible. The homes we have designed for the London Borough of Ealing are an example of how local authorities can effectively deliver sustainable affordable housing for their boroughs. Combining the benefits of good design with the reliability of Passivhaus standards and on-site renewable energy, local authorities have the ability to eliminate fuel poverty and successfully build high-density, cost-effective and zero-carbon homes in urban contexts that they and their residents are proud of. 

[1] The London Energy Transformation Initiative, LETI Embodied Carbon Primer, Supplementary guidance to the Climate Emergency Design Guide, p10
[2] Construction Report, The Passivhaus Trust, 2019

© Bell Phillips, Ealing Housing, Norwood Road. Visualisation by Secchi Smith