Why building-services contractors must take to off-site fabrication
The many benefits of off-site prefabrication — Robert Higgs.
Contractors are gradually shaking off their traditional suspicion of off-site fabrication, and now they must it embrace it as the best way of meeting quality, cost and performance goals, says ROBERT HIGGS.Conference organisers and strategic thinkers all love off-site fabrication. The subject encourages endless rehearsal of the advantages and so generates plenty of debate. Whilst some leading, visionary M&E contractors which are members of the HVCA took the leap some years ago, it has been much harder to win over other building-services contractors. Moving as much work as possible away from the building site is vital if we are to hit ever tightening deadlines, meet quality goals and improve sustainability. As former CIBSE president Terry Wyatt rightly never tires of pointing out: ‘The worst place to build anything is on a building site.’ Rain, wind, snow, mud and cold are not helpful to achieving quality construction, nor do they entice new recruits to our industry. Factory-based building work allows better and safer working conditions and reduces defects. Many building-services systems now leave the factory fully tested and commissioned ready to simply ‘plug and play’. This approach reduces expensive time, delivers a better finished product and dramatically reduces waste to landfill sites. It is staggering that almost 13% of materials delivered to site are never used; that is not only environmental vandalism, it is also financial suicide. Add that to the expensive man-hours wasted on fixing problems that should have been sorted out before the equipment was delivered, and you are getting very close to the heart of the industry’s most serious failings. However, many benefits that seem so obvious are not being enjoyed, and the industry is a long way from fulfilling the potential of this approach. It is not as if prefabrication is new. ‘All this talk about offsite manufacturing drives me mad,’ says Barry Pollard, chairman of the HVCA’s Ductwork Group. ‘What have ductwork firms been doing since the year dot? Now we are being told that this is what the industry needs to sort out its quality and cost problems, but we have been prefabricating offsite since the 19th century.’ He is right, but the ductworkers’ approach was never taken up as widely in other trades. Major clients are also committed — just look at the speed of progress at Heathrow’s new Terminal 5 where BAA operates a 65% prefabrication policy. Yet, according to figures released last year by BSRIA, the industry as a whole has not embraced off-site fabrication. There is progress, but it is surprisingly slow. Of the £1 billion spent by the construction industry on pre-fabrication last year only 4% (£35 million) was building-services plant. This figure is rising gradually, but it is astonishingly small considering the suitability of this approach to our sector. Offsite work can include almost any building service. Packaged plant rooms, including boiler houses, air-handling plant rooms and water services, are proving extremely successful with specifiers who choose them. Toilet/bathroom pods, integrated ceiling modules, pump sets, pre-assembled wiring, HVAC distribution systems, and prefabricated window units incorporating trickle ventilation are tried and tested. So what is holding us back? I still hear people argue that it is more expensive. The initial cost of individual components may be higher, but what about the overall saving? Pre-fabrication can shave serious amounts of time and money from site labour, which accounts for 25% of total construction costs. Sadly, however, this is often not considered when pricing the system — it’s that initial capital cost obsession of ours again. Prices quoted for individual pieces of plant exclude the cost of sending out enquiries to the seven successful suppliers — plus at least 14 unsuccessful ones — evaluating quotes, negotiating final prices, sending out orders, expediting delivery and site co-ordination. Then you have to pay to build and re-build the assembly on site when it does not work properly. Some people worry that off-site working will lead to the loss of traditional trade skills and move away from the local supply of labour to sites, but those skilled people can be moved to off-site centres where they will be more productive. As prefabrication grows in popularity more manufacturing centres will be needed. We have long passed the point where we need to go on rehearsing the arguments. Our industry is under pressure to improve its performance, and the very existence of off-site techniques means if we don’t do it, clients will find someone overseas who can. The EU Energy Performance of Buildings Directive will further up the ante, and greater use of off-site fabrication of building services will be a must to meet the requirements. Over the next three years, we will see the introduction of asset and operational labels for buildings over 1000 m2. These will give us much more information about good-practice benchmarks, which can be fed back into future designs. The difference between a building’s asset and operational label will show how well we have done our jobs as designers. More off-site fabrication will make it more likely that buildings will perform as they were designed to perform, and that means going further than just plant rooms. We will have to consider making as much of the building as possible off-site — ‘to get construction out of the medieval state it’s in,’ as Professor Wyatt so eloquently put it at a recent conference. The construction industry wasted £2.1 billion-worth of potential profit last year. Even shaving a few percent. off this figure could make all the difference to our sector next year. Engineers have to get away from the idea that all designs need to be bespoke. That is different from saying all buildings must be the same. Prefabrication is not about supplying identical boxes, but it does encourage a design rigour that depends on widespread use of standard components and modules. We are partly restricted by the traditional design process, which depends on too many people designing and then re-designing the proposed scheme. Once the consultant has checked and re-checked, the contractor tends to pull the whole thing apart again and sources components from dozens of suppliers. This is wasteful, time consuming and often produces a system that doesn’t work properly. Prefabrication solves most predictability issues, but if you are going to take this route you have to do so from the outset, which means developers and their designers need to adopt a different mindset and consider the system as a ‘package’ before they even start. To do pre-fabrication well you have to establish a more disciplined ‘right-first-time’ design process. Consultants and contractors have to think a bit more like manufacturers and see their system as a product. Pre-fabrication is also not just about saving money and reducing site waste. It is also a ‘quality-of-life’ issue. What value can you put on not keeping your workforce hanging around all day waiting for a crucial component to arrive and then having to work through the night to commission the system? What about the benefits of giving operatives more comfortable, safer and weatherproofed working conditions close to where they live? What positive impact will that have on our ability to recruit future generations of workers? By addressing all these issues, we as a sector will start moving towards true sustainability. Robert Higgs is director of the Heating & Ventilating Contractors’ Association, Esca House, 34 Palace Court, London W2 4JG.