Homes England’s study will be influencing housing delivery in several years’ time. We need it right now, Andrew Mellor says 

Andrew Mellor_PRP_crop

In 2019 the government formally responded to the House of Commons select committee’s report on modern methods of construction. The primary objective was – and still is – to increase housing supply and diversify the products offered by builders and developers.

With a government ambition for 300,000 new homes per year by the mid 2020s, MMC is seen as playing a key role in meeting that target. The response to the select committee report included commitments to stimulus funding, training and research, all intended to support the growth and development of MMC in the housing market.

In May 2020, Homes England announced that it would be commissioning research into MMC using its own sites as the case studies, with data being collected and evaluated over several years. Importantly, the selected sites are using a range of MMC solutions including panelised systems and modular in both timber and light gauge steel.

The research was intended to cover a range of themes and compare them to traditional construction, which included the required skills, costs and programme, energy performance, construction waste, safety and defects. The research aims to provide valuable data with regard to improving industry products as well as providing greater industry and consumer confidence in the MMC homes.

A few weeks ago, Homes England announced that it was publishing a report which confirms the research themes and outlines the research methodology. The research will include the gathering and analysing of data from eight development projects with more than 1,800 MMC homes. It will focus on the on-site delivery stage of the construction process.

The research includes 15 varied themes to capture time, cost, technical and social data. These include:

  • pace of build: factory, delivery and on-site built times
  • labour: productivity and trades required on site
  • costs: cost out of the factory and site cost
  • safety: site and factory incidents
  • waste: embodied carbon, site waste volume, energy and water use on site and in the factory
  • energy efficiency; SAP rating
  • defects, post completion and related costs
  • lifecycle: adaptability, maintenance costs and end of life
  • social value: impact on community during construction
  • wellbeing: benefits of the homes to the occupants

Homes England acknowledges that one constraint is that a traditionally built development is not included. Such a development would have provided counterfactual benchmarking data and as such it seems to be a mistake not to include this especially when one of the aims of the research is to demonstrate to industry the benefits of MMC.

If the research team cannot gather counterfactual comparative data from other sources, then there will be no accurate way of determining the benefits of MMC over homes of traditional construction.

There will of course be waste produced in the factory, but this seemingly has also not been included. It would also be prudent, in my opinion, to include fire and structural safety given the emerging safety legislation.

Can passive fire measures be installed to a higher quality than in traditional construction? Are there benefits of using MMC for the provision of golden thread information given that BIM and 3D tooling software will undoubtedly be used?

Given that there have been established defects with the structural connections of completed MMC projects, how do these case studies compare to available data on these defects?

Energy efficiency will be compared using SAP. Many of us understand the limitations of SAP and that it is a desktop tool. I suggest that what is really required to analyse the dwelling’s energy performance is air permeability testing on completion and post-occupancy data collection over a period of years to understand if the air permeability changes, and how energy use compares to the SAP predictions as well as over time against any air permeability rate changes. Ideally this data should be analysed against comparable data from traditional constructed dwellings so that the MMC dwelling performance can be benchmarked.

While this important research will provide valuable data, it would seem that it could provide more by extending the research themes and using traditional construction case studies for comparison purposes. The fact that the research will take several years – and it is understandable why it will – means that it will not fully influence housing delivery until the mid-2020s. This is exactly the period that the government has set the target for delivering 300,000 homes a year.

Is the research therefore not too late? It would seem so given the aim for it was to influence housing delivery over the coming years.