CPD: Offsite M&E manufacture
- Why offsite manufacture is becoming more important
- What the benefits are
- How it works in practice
3D CAD and BIM are making offsite manufacture of M&E modules a compelling alternative for many projects. Steve Tovey, director of Balfour Beatty's Modular Systems +, outlines how it is taking hold at its projects.
The application of offsite manufacture and assembly of M&E products is gathering pace in the construction of all building types. Of course, this is nothing new: the building services industry was using prefabrication, particularly of pipework services, 30 years ago. But what has changed now, with the increasing need to improve safety standards, quality and compress construction programmes, is the capability and technical skills to convert and break down conventional building services designs into individual products.
The development and use of 3D CAD and recent implementation of Building Information Modelling (BIM) enable projects to be designed with offsite manufacture in mind from the outset.
While these processes now give greater flexibility and mean that changes in design can be easily accommodated, an early design freeze is essential as any modifications during the manufacturing timeline will reduce the significant cost, programme and sustainable benefits that offsite manufacture provides.
A number of M&E services contractors now have manufacturing facilities allowing services to be supplied in a modular format. Modular Systems + is the brand under which Balfour Beatty Engineering Services (BBES) develops and manufactures modular mechanical and electrical products ranging from small electrical modular wiring components to multi-service modules and complex, fully operational packaged plant rooms.
Utilising purpose built offsite manufacturing facilities such as BBES’s facility in Wednesbury in the west midlands, M&E products can be manufactured and assembled in conditions which greatly improve the ability to deliver innovative and value engineered solutions across all types of building. Manufactured products can be incorporated equally into new build and refurbishment projects and enable main contractors to significantly reduce and re-sequence programme periods.
The factory conditions enable high levels of safety, productivity and quality to be reached and enhanced sustainability benefits, effective cost control and programme certainty to be achieved.
In addition, utilising the just-in-time manufacturing philosophy, each modular component is designed and built only when needed.
Project managers can generally work on the basis that offsite products could save as much as 15% compared with the traditional installation and at worst give a cost neutral outcome. And this does not take account of the hidden cost benefits.
The offsite manufacturing process can help site management by reducing the number of resources on site, leading to reduced logistics and welfare arrangements. Meanwhile, site scrap, packaging and waste materials are minimised as these are all accommodated within the lean processes offsite.
The role of offsite manufacture on any project is broad ranging and can be extended from the supply of common M&E products such as multi-service corridor modules with pipework, ductwork and electrical containment to much larger products where the building structure and fabric is incorporated, for example in multi-sectional plant rooms.
In reality, the only limitation to the size of product which can be designed and manufactured offsite is the transportation, where vehicle size and highway regulations dictate and commonly restrict load sizes to 14m x 4m x 4m. Though the amount of services that come in modular form varies from project to project, as a rule of thumb, 60-75% of M&E “first fix” installation works are offsite (that is, the infrastructure for services like cables and pipes for water and electrical services). After that, 70-100% of M&E work in plant rooms is now offsite.
There are almost no restrictions on the use of offsite manufacture – the main considerations that can impact a decision to use it include site logistics and access. Early engagement during the design and planning phases will identify these points and enable restrictions to be incorporated.
A modular riser is lifted onto the site at HMP Oakwood
Products are split into four key categories: multi-service horizontal (corridor) modules; vertical (structural) risers; sectional plant rooms/plant skids; and modular wiring systems. Within each of the key categories further sub-components are manufactured. The product manufacture is dependent on good quality 3D CAD drawings fully coordinated with the building structure — so the use of modular construction processes works best when an integrated approach to design of the structure and services is adopted. Often, the structure is designed with services being something of an afterthought.
Using these processes the product assembly becomes straightforward with clashes eliminated and technical issues and access all visible at an early stage. A major benefit to clients is the ability to produce prototypes of products which can be inspected and trialled prior to construction works starting on site.
Products manufactured and assembled in offsite conditions are subject to strict quality assurance processes which result in high-quality standards with full traceability of testing and inspection, something not always achievable with conventional site installation.
As mentioned above, the delivery of the M&E products must be considered at the earliest stage of the design, planning and programming of the project to achieve the maximum benefit for all parties. Sufficient upfront time needs to be allowed to carry out the design and engineering activities and then to consider these within the overall build strategy for the project.
If considered early enough, significant additional benefits can be gained through incorporation of other construction activities within the offsite strategy, for example ceiling details and supports, and partition wall construction including fire stopping. The time spent early in the project will drive programme benefits and can realise 30-40% savings in the time required for first fix activities.
The early involvement must then be used to build relationships and collaborate with other members of the design team to develop a fully coordinated and complete design. This is essential to ensure the manufacturing process is used to provide its maximum benefit in terms of buildability, repeatability and quality. Although each modular component is designed and then manufactured only when needed, planning of the handling and movement on site must be considered in the build programme to prevent the need for costly storage.
Where early involvement is achieved the M&E consultants’ design can be developed to fully incorporate how the services will be broken down. The ability to translate information from the design drawings direct to manufacturing drawings greatly improves the programme benefits that offsite manufacture provides, but does not preclude an offsite strategy being implemented after a design has been completed. This requires consideration of how products will be developed and the final coordinated drawings to be developed with manufacture in mind.
In considering the initial scope of works for offsite manufactured products, thought should also be given to the incorporation of specialist works such as fire protection sprinkler pipework and BMS controls.
To gain maximum benefit all offsite assembly components should be labelled and be clearly identifiable, and where possible, testing and commissioning should be completed at the factory. This consideration can significantly reduce commissioning times on site, reduce costs and contribute to a successful completion and handover.
A healthy option
One project where lean manufacture, just in time delivery and prefabricated M&E components helped to deliver a cost-effective, energy efficient and safe build solution was at the UK’s second largest healthcare site, Queen Elizabeth Hospital Birmingham (QEHB). Balfour Beatty’s project director for the £500m scheme, Roger Frost, was named Construction Manager of the Year 2011.
Designed by BDP architects and built by Balfour Beatty for University Hospitals Birmingham NHS Foundation Trust, BBES was appointed to complete the £230m M&E package at the 137,000m2 hospital after the company successfully demonstrated its Modular Systems + team had the capability to use the latest offsite, prefabrication techniques to deliver significant savings in man hours and expenditure, as well as providing a much safer way to work.
BBES’s Modular Systems + team designed and built more than 600 shower and WC pods that were installed throughout the hospital. Utilising a quick, simple and repetitive installation process, the units were assembled offsite to eliminate the need for hot works such as welding or brazing of pipework joints at the hospital, saving 6,800 man hours.
At Queen Elizabth Hospital Birmingham, a total of 452,540 man hours were saved using offsite manufacture
However, it was in the creation of the complex M&E systems for the project that BBES’s offsite capability was able to truly shine. In total, hot works were reduced by 112,220 hours, onsite manual handling cut by 156,480 hours and working at height was reduced by 183,840 hours.
In fact, offsite prefabrication enabled the M&E elements of this project to be completed 12 months ahead of schedule while reducing man hours by an astonishing 452,540 hours when compared to a traditional M&E approach.
BBES also utilised an innovative modular wall system and delivered more than 300 ward wall modules to site, each with integrated services as part of the overall design. The complete wall panels include electrical accessories, medical gases, nurse call and lighting, with all electrical and mechanical services built in. The panels have anti-microbial vinyl coating, and are fully fitted with no follow-on finishing required.
The hospital was also supplied with offsite manufactured services risers, plant rooms, modular wiring and more than 1,800 modules supporting ductwork, pipework and cable containment.
The easy cell
The creation of new prison facilities is another area that presents opportunities for sustainable improvements and in terms of M&E components, there are a vast range of requirements, including heating and ventilation, comfort cooling, power, lighting, fire detection and security/CCTV.
At HMP Oakwood, a new £200m prison facility in Wolverhampton, BBES’s offsite approach for main contractor Kier Construction and client the Ministry of Justice reduced man hours on site by approximately 50% when compared to a traditional M&E approach.
Offsite modularisation of M&E components included fully serviced four-storey risers, electronic water control panels and “plug and play” underfloor heating pipework. It not only saved on labour time but also delivered associated build efficiencies, consistent quality, reduced waste and safer working conditions. This was the first time such an innovative approach had been used in a UK prison, but the results speak for themselves.
The modular risers installed at HMP Oakwood were developed with the client and project team over a period of nine months. There are 240 risers in total with 180 four-storey risers comprising all services that were tested and insulated offsite.
At 11.5 metres long, each riser is able to service multiple levels and was installed using a bespoke lifting method developed by BBES. An installation rate of five units per day reduced the amount of hours spent on site when compared with traditional methods.
The BBES team also installed 12,000 pre-formed conduits in pre-cast concrete panels. Incorporating unistruts in the pre-cast structure meant the team was saved the task of drilling 70,000 holes in concrete which would have had to be done while working at height.
As part of the project, Modular Systems + also delivered a fully modularised energy centre to provide a number of sustainable building service systems, including four 0.35MW dual fuel boilers, a 1MW biomass boiler and combined heat and power unit.
To meet the client’s strict sectional completion dates, the Modular Systems + team used a fully integrated lean construction philosophy with offsite manufacture of key importance. Maximising project efficiency – both on and off site – the process was monitored weekly to ensure the project could be handed over on time.
All components were fully tested at the BBES facility as part of quality control procedures. Every component produced was provided with complete traceability to ensure absolute quality is delivered every time.
Offsite checks in at Heathrow Airport
When a building has to be constructed on a constrained site surrounded by the airside operations of one of the world’s busiest airports, traditional construction methods sometimes have to take a back seat. Terminal 2’s new satellite pier is being delivered thanks to BBES’s Modular Systems + facilities and knowhow. Representing another milestone in the modernisation of Heathrow Airport, as well as being the largest ever airside project at the airport.
Set to be fully operational in 2014, the new £2.5bn Terminal 2 facility has an overall construction cost of £560m. Procured by Heathrow Airport Limited (HAL) in two phases, Balfour Beatty delivered six of the pier served stands in 2010 as part of Phase 1 with Phase 2 currently under construction by an integrated project team from Balfour Beatty delivering the remaining 10 stands ready for completion in October 2013.
From the outset, space was at a premium and traditional methods for the installation of the building services and associated works were potential logistical nightmare especially considering that the entire site is locked down under an airside security regime.
Faced with challenging airside constraints and the client requiring all projects to be constructed using a Design for Manufacturing and Assembly (DfMA) approach, BBES’s offsite pre-fabricated assembly of the main service modules has greatly aided the sustainable delivery of the Terminal 2B departure pier as well as significantly increasing project efficiencies and offering the least disruption to wider airport operations.
All the mechanical, electrical and public health (MEP) modularisation requirements were incorporated into the production design by the BBES design team. Detailed development of the coordinated working drawings were then issued, in 3D model form, incorporating all BIM material information, to the company’s Modular Systems + offsite manufacturing facility.
The MEP solutions for Phase 2 were comprehensive and included everything from multiservice risers, each of which could be installed in one night compared to six weeks using a traditional approach, to vertical circulation core air handling plant rooms, which were transported across the airfield overnight and structurally fixed into position in two days each, a massive saving when compared to 13 weeks for a traditional installation.
The Apron Service Corridor multiservice modules were delivered in sections and formed the spine of the services distribution while a complete major mechanical plant room could be delivered in eight sections and installed in two weeks, shaving 24 weeks off a traditional installation. Further solutions included multi-service modules for the full length of the 250m long passenger tunnel as well as modular wiring, pipework and containment for all substructure areas.
In all, our Modular Systems + facility supplied 549 modules of various types with a combined length of around 3km. With components being manufactured and delivered for immediate installation in the building, our offsite approach has saved more than 115,000 M&E operative site hours along with associated build efficiencies, consistent quality, waste reduction and safer working conditions.
Steve Tovey is director of ModularSystems + and Site Services www.balfourbeattycsuk.com/capabilities/modular-systems-plus/