Alison Crompton, Regional Director at AECOM shares her viewpoint from our Housing Londoners report, exploring the importance of MMC in delivering low-carbon homes.

Decarbonising the UK’s housing stock, both old and new, will play a significant part in the strategy needed to deliver the UK Government’s commitment to reduce greenhouse gas emissions by 100 per cent by 2050.  Modern methods of construction (MMC) are already being used to deliver better new build housing faster, and  they also have the potential to aid us in delivering low carbon homes.  But what is required to accelerate and sustain this opportunity?

 

 

Lessons can no doubt be learnt to support the use of MMC and off-site manufactured components in retrofitting existing homes as well to reduce their carbon impacts.

 

The Homes England Strategic Plan 2023 to 2028, launched in June 2023, provides a strong signal to the market. It references the increasing uptake of MMC by large and mid-sized housing developers who are currently using it in some form. However, its greater potential to revolutionise the sector and aid in reducing carbon emissions. alongside other benefits, is not being utilised. The Plan notes there will be support from Homes England to drive the growth of the MMC sector by incorporating requirements into programmes and contracts, paramount to ensure the sector’s long-term survival.

 

MMC solutions may be leveraged to make a positive local impact, with modular housing companies providing employment in local communities.  Market-led support for the growth of this sector is paramount to ensure modular housing companies can survive; this is a current issue within the sector resulting in some notable business closures.

 

If we are to meet net zero carbon ambitions, a fabric-first approach to housing design is essential. Solutions that identify and optimise fabric-first factors such as insulation levels, airtightness with controlled ventilation, and avoiding thermal bridging will inherently deliver low energy homes with reduced running costs. Lower embodied carbon compared to traditional construction can be achieved through the choice of the structural framing material, for example selection of timber or cross laminated timber for the frame or structural panels. 

To ensure a successful outcome, early commitment to MMC is needed.  House designs should incorporate available panel sizes and targeted insulation standards match what the products can deliver.  The site layout and logistics must enable the delivery and storage of pre-manufactured elements in bulk, including having an accessible compound where deliveries can be weather protected.

 

Early engagement with the supply chain is likely to require early financial investment; the MMC provider will need to be paid upfront rather than paying separately for products and labour. This early investment can potentially deliver benefits, providing cost and programme certainty in a rising market during labour shortages (for example, when there is a shortage of bricklayers). 

 

It is critical that a fully integrated team – from the client and the design consultants, through the supply chain and construction teams – comes to the table as early as possible to agree and sign off on elements such as space, materials and intended use, prior to production. This requires a mindset that is radically different from traditional ways of working.

 

An example of MMC delivering low carbon homes is the INNO solution – an offsite volumetric housing system AECOM have been involved in alongside architects RSHP and manufacturer @Home. Crofts Street is the first modular homes to be built as part of Cardiff Council’s flagship housebuilding programme with Wates Residential. Assembled off-site, the homes were constructed on-site within one week, minimising local disruption and accelerating the occupation of the 100% social housing scheme. Adopting the fabric-first approach, the Crofts Street houses are designed from a hybrid of sustainable materials, delivering high-performing homes which exceed current regulations in fire, acoustics and thermal insulation, significantly reducing the running and heating costs for residents and increasing occupant wellbeing.

 

Finally, one important lesson from the research project AECOM carried out for BEIS (now DESNZ) entitled Building for 2050 is that developers and designers must not focus on a single theme. Those designing successful low carbon homes will have considered carbon emissions, energy use, running costs, buildability and usability for the occupants in the round.  The same is true for homes built using MMC; a wide range of factors need to be taken into account to ensure the resulting homes deliver the performance and comfort intended, thereby forming part of London’s response to climate change.