Prefabrication and Sustainability - Lessons from the UK

The UK’s prefabrication industry is flourishing, with offsite methods of construction being incorporated into myriad developments to deliver time and cost savings as well as significant sustainability improvements. Here, Martin Goss, Managing Director of Mtech Consult, the UK’s leading independent consultancy in prefabricated building methods, discusses what the USA can learn from overseas about this low-impact building technique to start reaping the ecological and economic benefits.

In the UK, the benefits of offsite construction (OSC), which the USA knows as prefabrication, are widely acknowledged: the shorter build times ensure less time is spent on site and a more immediate return on investment, and the reduced work required on site lessens health and safety issues and limits delay through inclement weather. In addition, increasing engineering within a controlled environment ensures the highest levels of accuracy and, therefore, fewer costly snagging issues. Perhaps more significant for an increasingly environmentally conscious industry are the substantial sustainability improvements that offsite construction methods can achieve, both during manufacturing processes and the building’s in-use performance.

Going global – impact measurement

Mtech Consult has worked in a global capacity in both the public and private sectors, experiencing how different countries view, manufacture and implement fast-track offsite construction methods.

In every case, it’s been clear that a method for properly determining the environmental performance of offsite construction compared to that of traditional building methods has been essential. The most credible way to measure the environmental improvements of a building method or product is to conduct a cradle (extraction) to grave (re-use and/or recycling) Life Cycle Assessment based on the UK’s Building Research Establishment (BRE) or worldwide Leadership in Energy and Environmental Design (LEED) methodology.

Measuring the environmental impact of volumetric modular construction compared to traditional back-to-back building methods shows that OSC can typically lower the overall footprint of a project by an impressive 38%. It can also deliver a 42% reduction in CO2 and yield a 21% improvement in the use of energy for building and maintenance.

Despite this, the popularity of prefabrication hasn’t caught on in US construction as much as expected. Perhaps because of the prevailing popularity of Design & Build, or due to a convoluted procurement process, construction in the States has remained largely craft-based. The way a nation builds is a result of its social, political and economic history, and countries that have traditionally been heavily unionised can find it difficult to introduce new construction methods if a Union does not support them. However well-intentioned the motivation for not backing emerging techniques - whether job preservation or economic vigilance in a time of global recession - this could stifle innovation, which is the lifeblood of sustainability.

And, although craft-based construction can be a financially and socially sustainable way to build, figures show that it is certainly not the most environmentally sustainable. In addition reducing the embodied energy of the build, it is far easier to ensure that a prefabricated building is constructed from recycled materials, as a factory has greater control over the supply chain than a construction site does.

Spreading sustainability through offsite

Prefabrication also lends itself to efficient and more sustainable methods of transport, such as rail, ship or barge. The UK is currently using barges to transport construction materials to the Olympics site, for example, and some UK construction giants even have built rail heads next to their factories to facilitate deliveries. And, where road transport is used, prefabrication results in 90% fewer vehicle deliveries to site compared to traditional non-prefabricated building methods. This doesn’t mean to say that there is a specific radius in which prefabricated structures are manufactured and delivered; this is usually a commercial decision, influenced by environmental impact.

Waste reduction is another significant sustainability advantage feature of deploying offsite construction techniques. Research conducted with the UK government’s waste reduction department, WRAP, shows that factory-based construction methods can reduce material waste by up to 90%.

So, how to convince the US built environment sector to adopt the offsite construction methods that have so benefited the UK? In the public, private and commercial arenas, repeatability and predictability are of huge importance, as is the guarantee to meet deadlines and, of course, sustainability. Offsite construction certainly delivers on each of these requirements, and if adopted early in the design process can slash build times in half depending on the project. Even when OSC isn’t adopted particularly early on, typically up to three weeks of an 18 week build schedule can be shaved off.

Although one of the major benefits of offsite construction is that a building type has been designed before and has therefore been proven to work, it’s not to say that prefabricated buildings are all designed to a set template. Working with architects at the earliest stage possible means that tried and tested building types can be customised to better meet an architect’s needs, and enables collaboration to craft an entirely new, bespoke module if necessary.

In addition to OSC making the building process more sustainable, the reduced opportunity for human error thanks to precision engineering presents another significant advantage, as it results in a more energy efficient – and therefore more sustainable – building. The building can also incorporate as much energy saving technology and as many efficiencies as the architect wishes, addressing daylighting issues, indoor environment quality etc just as an on-site build would.

To some extent, the US procurement process needs to change its model to fully accommodate offsite construction. Manufacturers of these systems really need to be consulted at design stage, because the earlier in the process offsite construction methods are specified, the greater the time and cost savings, and the more impactful the environmental benefits.

What next for OSC?

The future for OSC in the UK and across the globe is certainly looking bright. Innovations such as bathroom pods or volumetric modular bedrooms complete with curtains, wallpaper, tiles and taps for use in hotels, student accommodation and the like, give the option of reducing or adding to a building with complete repeatability in line with demographic demand and are becoming increasingly popular. Ultimately, it is this standardisation that means OSC will work so well for the US market. What’s more, the factory environment is best placed for furthering other developments, such as the use of post-industrial and post-consumer recycled materials, and methods for building more while using less.

The UK’s advances within the offsite sector have already positioned it as the worldwide ‘centre of excellence,’ with many countries across the globe watching its progress in trialling new systems. With the UK’s drive towards innovation gathering speed, now is the ideal time for the USA to capitalise on the advances being made in the offsite sector. The UK and the USA have been powerful partners throughout history, and the offsite sector presents a great opportunity for setting the construction agenda while occupying an influential thought leadership position on both sides of the Atlantic.

Case Study

Lessons worth learning - sustainable schools

Under the UK Government’s Building Schools for the Future programme, two new low-carbon schools in Sunderland needed to be completed sustainably and on time, ready for the start of the new school year. The schools required plant rooms, or energy centres, with low carbon footprints that could integrate zero carbon onsite generation with traditional high-efficiency components such as condensing boilers and variable speed drive pump systems.

Heating, ventilation and air conditioning specialist, Armstrong Integrated Systems, which worked with Mtech Consult on the Innovate Offsite feature at Ecobuild in London this year, was engaged to cut the overall project timescales, streamline the installation of building services and keep traffic on the site to a minimum. Each of the fully integrated LZC prefabricated energy centres was constructed at Armstrong’s UK manufacturing facility, before being delivered to site fully-assembled.

Manufacturing the plant rooms offsite made it possible for construction to proceed concurrently with the rest of the project, and meant that assembly could continue regardless of the weather, all ensuring work finished on time and the schools could open in line with British semester dates.

Neither Martin Goss nor Mtech Consult Ltd receives any remuneration or gain whatsoever for referencing manufacturers in editorial content; other suppliers may provide similar products and inclusion in no way implies Mtech recommendation of a product for any specific project.