Off-site manufacture is proving cost effective, sustainable and ticks building regulations boxes

Introduction

With construction providing 6% of UK GDP and over one-third of this generated through the housing sector, pre-fabrication or off-site manufacture has established efficient, cost-effective solutions that have been translated into other end markets. This includes mechanical and electrical engineering components, structural components, cladding and curtain walling panels, pods and complete accommodation units through off-site manufacture.

In other markets, prefabrication and off-site manufacturing (OSM) is expected as standard.

The key benefits of off-site manufacture have been well documented across the UK construction industry with a wealth of case studies and exemplars already built and operational. The key benefits are:

  • Performance - components that are performance specified for simplicity and speed of installation
  • Programme - simplification of the critical path and increased levels of productivity
  • on site. OSM can reduce on-site programme durations by an average of 50%
  • Quality - factory-based manufacturing accuracy; learning, development and product/process innovation. (Some off-site building systems will exceed Building Regulations requirements for air leakage by up to 70%)
  • Whole-life cost - improved and rationalised design and manufacturing process can reduce the operational consumption of the unit/component, defects and repair process
  • Sustainability - gains from enhanced performance and efficiency of the components/unit; waste reduction both in the static element and dynamically across the full asset; reduced site traffic; operative travel; reduced site waste. (Research for Wrap has shown that off-site construction can reduce on-site waste by up to 90%)
  • Safety, working conditions and recruitment - fewer trades on site, full year operational facilities in controlled environments
  • Maximising return on investment.

The case for modern methods of construction is being supported through legislation as well as key industry bodies and clients. The drive to reduce carbon (embodied and emitted) is evident and will look to achieve the targets set. These are already impacting on design and construction practices. The legislative constraints that require built assets to use less energy in their construction and consume less energy in their operation will require better design, specification and construction. New products, materials and, critically, higher standards of workmanship across the life of the asset are essential. There is a growing body of evidence to prove that OSM or modern methods of construction or design for manufacture can impact on waste while delivering great architecture with savings.

View from the market

The architect of the two-day construction build McDonald food outlet and chairman of Buildoffsite, Richard Ogden, believes that OSM is “on the cusp of a step-change” with the catalyst being the carbon agenda. With OSM accounting for 10% of the UK’s construction market and projected growth of 100% to 2020, where are the opportunities for growth in a depressed economic climate and what areas of OSM are servicing that need?

Engineering services firms and housebuilders recognise the benefits of OSM. Large repeat clients such as airport operator BAA, hotel chain Premier Inn and the Ministry of Justice have all been delivering major programs of construction using OSM 2D/3D components or modules. Laing O’Rourke is recognised as one of the UK leaders through its investment in its Explore Industrial Park, Steetley, which provides one of Europe’s most advanced OSM facilities producing precast and pre-assembled products. OSM provides a key advantage therefore in a major contractor’s portfolio, delivering value and innovation into the market.

However, as a consequence of the economic crisis, public sector spending reviews and cuts, there have been some notable casualties in this area. Tata Steel closed down its OSM operation in Shotton, North Wales in October 2010 with the loss of 180 staff. RB Farquhar’s hire business was sold to the Elliott Group in November 2010 following the remainder of the group going into administration the same month. Britspace Modular Buildings also went into administration last month; a firm with over 40 years’ experience of delivering both modular buildings and bathroom pods. Clients and project teams take note - do your diligence on suppliers and manufacturers to ensure their financial viability.

So in this climate, are there any opportunities for growth for OSM or is it just a case of fighting for survival? The warm market areas are in London and the South-east with the offices and prime or super prime residential sectors both providing confidence. Developers such as Land Securities and British Land are utilising modular pods (Ropemaker Place and 201 Bishopsgate) to gain programme, quality and sustainability gains. In other areas of the country, refurbishment and maintenance work is providing low-cost, efficient and sustainable repair and maintenance solutions, and delivering value into a depressed market. We are also seeing opportunities in the residential and housing markets where historically OSM has provided an advantage, dependent on this sector showing signs of recovery. Finally, with demand emerging in the primary school sector, major cities require investment in this area to support consequential development in secondary education facilities in three to five years’ time.

New sectors for OSM are starting to emerge to provide an offset to depressed markets. Yorkon, part of the Portakabin Industrial Unit within the Shepherd Group, has been appointed to provide the first active nuclear analysis laboratory at Dounreay in Scotland, valued at £7m - OSM provides an advantage for the security and logistics of this type of facility. Opportunities exist beyond the UK - Portakabin has invested in a factory in France to serve the European market, focused on the manufacture of its Ultima modular building product.

Balfour Beatty Engineering Systems approach to OSM

spec costs

Innovation/development of OSM

In 1994, the Latham Report “Constructing the Team” along with the subsequent Egan Report “Rethinking Construction” (1998) and “Accelerating Change” (2002), suggested that waste in the industry accounted for 25-30% of project costs and looked to encourage the industry to view construction as a manufacturing process.

With the introduction and expansion of CAD/CAM, the potential of BIM is only now starting to be realised, with a direct impact on OSM within the construction market.

A number of designers, manufacturers, suppliers and contractors are already exploiting the gains of OSM in their production processes, providing clients and project teams with further additional benefits related to visualisation, quality control, work scheduling and exchange of information and attributes.

It is clear that OSM could be seen as one of the early adopters of integrated project delivery and indeed BIM. Viewed as still being in its relative infancy, the leveraging of information modelling in this context has resulted in gains across design optimisation (options and parametric modelling), providing additional attribute data into the model from the manufacturer and integrating Smart technology for operational and FM functions; virtual assembly and construction modelling and automatic call-off/just-in-time delivery.

Procurement

With major contractors developing consultant-like service offerings and approaches in the pre-contract period, the early appointment of suppliers and manufacturers using pre-contract services agreements is an appropriate method to engage these at an early stage. So what does a common or preferred approach look like?

Critical to the successful of OSM is creating a culture of design for manufacture among the project team, including input from manufacturers with the design and tender process.

End markets

Housing (single units to high-rise apartments)

A historic and established sector for pre-fabrication from the early twenties, the OSM offer in this market has matured. The main drivers for adoption and leading role of OSM/MMC in this market are skills availability, an ageing workforce, quality and tighter building regulations. Components from roof trusses and structural frames, structurally insulated panels (SIPs) are already widely used.

The most developed market for OSM, housing provides examples of construction across the subdivisions from social housing through to high-end private dwellings.

Education (nurseries, schools, colleges and universities)
For years, schools have used modular classrooms, either leased or purchased, to provide flexible teaching spaces attached to existing facilities or installed as temporary classrooms in recreation areas. The offer ranges from single classrooms or school extensions like in New City Academy, London, to the development of temporary foundation level spaces through to complete campus facilities as found at the London Metropolitan University Digital Manufacturing and Workspace Centre.

Target outturn construction costs of £1,600/m2 for schools is the new benchmark. Nurture Future, a collaboration between Tarmac Building Products, architect Cartwright Pickard, Davis Langdon and WSP, is developing blueprints at this level.

Healthcare (hospitals, operating theatres, acute wards, clinics and medical centres)
Taking a modular or off-site approach to constructing healthcare facilities lends itself well to the standardised room sizes and “modular” layouts in the HBN 11-01 guidance.

Circle Partnership and Health Properties have developed and are now delivering clinical services from their Foster + Partners-designed CircleBath hospital (£3,400/m2). Working as an integrated team, client “platforms” were created covering the structural frame, operating theatres, theatre support rooms, bedrooms and bathrooms. These were all rationalised but with high quality design and manufacturing and installation that were passed to the next projects in the pipeline, generating real cost (28-50%) and programme savings (minimum 20% on an 80-week construction and commissioning schedule).

Residential (student accommodation to nursing homes)
Much student accommodation has been constructed through the use of modular layouts, using steel frames and precast flooring, with the modules being installed subsequently. This process, on average, reduces build time by 50%.

Leisure (hotels to holiday lodges)
The use of modules in hotels has become the preferred option with only the interior FF&E and the cladding to the modules being carried out on site. The Travelodge Uxbridge in west London was constructed using 86 shipping containers, saving £500,000 and 10 weeks, compared with its equivalent traditional construction of a 100-bedroom hotel.

Public (armed forces single living and mess accommodation to custodial prison cells and ancillary accommodation)
The likes of Project SLAM, the Ministry of Defence project to improve single living accommodation for Armed Forces personnel across the UK, provided for the construction of cluster flats and prefabricated housing to meet demand for accommodation along with other opportunities such as rationalised designs for structures such as police stations and prison accommodation.

Retail (superstores to fast food outlets)
Precast and modular construction is being used particularly for pace of construction assembly and environmental consideration, thus generating a faster return on investment. Yorkon recently completed a modular construction for Tesco in Southam, Warks, evidencing increased clear spans in the sales areas (28m) and added eight weeks trading time through savings achieved.

Commercial (office developments)
Off-site construction has become a larger part of commercial developments, most recently at Great Portland Estates, 160 Tooley Street and on Sellar Development Services’ Shard project. Most interest in this area appears to be generated from environmental gains, indicating both the impact of legislation and the investor/tenant sentiment.

Sustainability

Efficient, safe and sustainable delivery of construction with operational gains is pushing OSM into the spotlight.

The award-winning EcoPod is a fully fitted, self-contained plant room, converted from a telecoms cabin. One of the first EcoPods was installed on the roof of Chartist House, a block of 96 flats (including 38 sheltered accommodation) owned by New Charter Housing Trust, in Hyde, Cheshire in 2009. CO2 emissions have been reduced from 160,000kg to 69,000kg, and residents’ gas bills have been replaced with a £4/week addition to the service charge.

A year ago, United House carried out a low-carbon retrofitting of a solid walled, three-storey Victorian terraced house in Camden, London using WHISCERS laser technology for the first time and pre-cut internal wall insulation and fit out, while the residents continued to live in the property. The retrofit is expected to deliver 77% carbon savings and reduce fuel bills by nearly £600 a year. The project also acted as a trial for rapid laser scanning as a tool to inform a complete application across older social housing stock.

Indicative costs

One of the key opportunities for professionals (QSs) is to capture data and to provide realistic whole-life benchmarking and comparison for clients and project teams.
Modules such as bathroom pods are fairly generic and are relatively easy to compare. The indicative costs of typical modular assemblies are as follows:

  • Shower module for student accommodation - £2,200-3,000 each
  • Bathroom module, affordable housing - £2,600-3,400 each
  • Bathroom module, city centre residential - £3,200-4,400 each
  • WC module - podwall - commercial office development -
  • £10,000-20,000 (3-8 units)
  • Bathroom module, business grade hotel - £4,500-6,000 each
  • Bedroom module, business grade hotel - £18,000-25,000 each

Costs are for fully finished modules, including site installation but exclude main contractors’ attendances and completion works such as external cladding and finishes outside of the module. Typical lead times are 14-20 weeks, with like-for-like schedule gains of between 40% and 50% compared with traditional methods.