Pretek's factory produces timber cassettes with services pre-installed
Here’s a regime-changing idea. Health Properties, a major repeat client, is targeting 50% cost savings through offsite construction and Design for Manufacture (DfM) on its ongoing programme of private hospitals. In cash terms, that means halving the £3,400 per m2 out-turn cost of its first completed project (see case study, over). It’s revolution is to deliver projects designed by top-flight architects, but planned by a new breed of pre-fabrication consultant. Back-of-house will be conceived as a kit of parts, but the viewer and visitor experience will aim for architectural excellence.
But, even as one major client is plotting to overthrow traditional methods, here’s another embracing the ancien regime. Volume housebuilder Taylor Wimpey is cancelling the remaining units to build out a 137-home scheme of factory-built housing by Rogers Stirk Harbour + Partners in Milton Keynes. One of the success stories of an earlier revolutionary campaign — John Prescott’s £60k house programme — has fallen victim to cost inefficiency and poor sales.
Rogers' Oxley Woods housing has been cancelled
In other words, the forces of revolution and reaction are pitched against each other. The clear advantages of offsite, particularly in the age of austerity, include faster, more accurate construction with less rework and waste, plus the ability to rationalise out costs and design in carbon efficiency. But the downsides are just as evident: clients’ fear of Identikit buildings and memories of past pre-fab failures; and the fact that cost, time and carbon savings often don’t make it to the bottom line when you have to tool up production lines and truck large components to site.
But forward-thinking clients, contractors and suppliers believe we’re now at the tipping point. “There’s always a point where something takes hold, and that’s when advances in a whole range of technologies come together,” says architect Peter Marshall, now chief executive of pre-fab panel manufacturer Pretek. “In the 1960s, we had the right idea, but couldn’t get the performance levels. Now, we’ve got better-performing materials, the IT and technical abilities, and the UK still has the manufacturing base to support it. ”
“DfM is coming in from the cold. It’s not about ‘pods’, it’s about joined-up high-level thinking between what the designers are trying to do and what’s on site,” says Jaimie Johnstone, director at Bryden Wood, a firm of architects whose role has now evolved into offsite consultancy for clients including Health Properties, Sainsbury’s and the Metropolitan Police. “We can get away from the idea of a pre-fab box — it’s about designing a series of choices, assembled on site by multi-skilled guys, with the Building Information Model automatically scheduling the ordering and delivery.”
In fact, the possibility of linking CAD models to CAM factory production, followed by BIM-driven site assembly, makes the most compelling case for offsite. “We think the two go hand in hand. In a virtual model, it’s easier to see the possibilities of offsite manufacturing. There’s no point having a sophisticated building system if you have to schedule it manually, or a sophisticated BIM model that you send a bunch of blokes off to build traditionally. As more and more people use BIM, we see more possibilities for DfM,” says Bryden Wood’s Johnstone.
As the industry searches for cost and efficiency savings, and hints grow that the Department for Education’s Sebastian James Review for the post-BSF schools programme will throw its support behind offsite builds and standardised design, the time could be ripe for an offsite uprising. Richard Ogden, chairman of membership organisation BuildOffsite, which brings together clients, contractors and consultants, argues forcefully (see page 22) that the days when traditional construction could adequately meet most clients’ aspirations are now over.
“Listening to Paul Morrell, the efficiency agenda is coming to the fore, and the expectation is that the supply chain will have to step up a couple of levels,” says Mark Cammies, property director of Health Properties. “Contractors tend to say ‘it’s the clients who drive this’. But if one contractor came to me with creative ideas, I’d bite their arm off,” he challenges.
Offsite is already here, of course. Scratch the stick-on cladding on a recent prison, budget hotel or student residence, and you’ll probably find modular bedrooms, bathroom pods and standardised design. It’s also been adopted by clients such as BAA and supermarkets that can factor repeat work and large pre-fab components into their programmes, reaping the economies of scale that aren’t available to one-off projects. But, for that reason, it’s been seen as unsuitable for public sector school and hospital buildings that require design individualisation, not to mention civic buildings, refurbishments or high-street infills.
But offsite doesn’t have to be a synonym for “volumetric”, which dictates regular room sizes, plans and sections. Nor is moving to DfM a straight choice between traditional build and lorries laden with pods. Instead, Bryden Wood argues that clients and design teams who can identify the common DNA between one project and the next can benefit from standardising that portion of their project - an approach it adopted when advising the Metropolitan Police on a series of police stations and custody suites.
“People tend to think DfM or offsite is all or nothing. We say, you can take a traditional product and standardise it, and replace a part of the building with a pre-fab element. You go on a journey to rationalise the building, gradually introducing a kit of parts,” says Johnstone.
And once construction teams start to think about ‘procuring commodities’, rather than ‘building buildings”, he points out that it becomes easier to negotiate bulk-buy deals with suppliers, cost-plan buildings, and watch the overall costs fall.
To date, offsite has often failed to deliver anticipated savings, as the cost of setting up factory production lines can make each individual beam, column or wall panel as expensive as its onsite equivalent. But suppliers and designers are now turning to “smart” offsite systems, producing standardised walls, beams, columns, cassettes and panels with enough dimensional flexibility to suit site conditions and design aspirations.
Stuart Piercy of architect Piercy Connor, an offsite champion since it devised the “microflat”, says: “We’re seeing customisable elements, that should help avoid the same mistakes [as the 1960s]. It’s about super-efficient standardisation, with elements of bespoke design.”
Suppliers entering the market, such as pre-fabricated panel specialist Pretek, are adopting this standardised-but-different approach. Nurture Future is a new venture from product supplier Tarmac and architect Cartwright Pickard, aimed squarely at the post-BSF schools market, and targeting out-turn costs of just £1,600 per m2.
“We’ve designed a kit of parts that any architect or design team can run with,” says partner James Pickard. “The system accommodates different frame, floor-to-ceiling and span dimensions, although a 1.2m grid would work most efficiently. Offices tend to have a 1.5m grid, and it doesn’t stop people designing interesting office buildings.”
Sir Robert McAlpine is an example of a contractor that is adopting a gradual approach to DfM, stepping up the inclusion of offsite “plug and play” plant rooms, modular wiring and sprinkler systems in its builds. But it’s now going a step further, maximising standardisation between one scheme and the next.
“In our schools programme, we’re looking more and more at adopting offsite and standardisation. We’ll be bulk-buying standardised materials, and trying to repeat foundation and frame details. We’re looking at having a single cladding module, if not the same cladding,” says McAlpine’s Robin Oram, head of education, and part of an industry steering group calling for greater product standardisation (see page 14). “One option we’re considering is a ‘book’ of standardised design details, for internal use.”
But while some contractors get the message, it’s not as simple as raising a flag for offsite and expecting the industry to rally round. Embraced fully, the philosophy requires different teams, playing different roles. The offsite fabrication consultant — or perhaps the “consultant contractor” — would take on early design development and client consultation instead of the architect or project manager. The offsite supplier would be responsible for elements of the structural and M&E design, de-risking the trade contractor’s on site assembly.
Once specification, fabrication and onsite erection is merged into a single process — all managed and documented in BIM — there’s little need for a QS to measure and value the work.
On site, using pre-cast concrete panels reduces the need for rebar, formwork, scaffolding and manpower. “The main contractors tend to use in-situ concrete because it’s very forgiving — you can drill holes later, you don’t need to worry about the services design on day one,” points out James Pickard, who fears that industry inertia could hold back good ideas. “When we launched Nurture Future, we noticed that a lot of the main contractors sent along their middle managers — the senior managers with clout didn’t come.”
And while logic might suggest that today’s market would drive us towards offsite’s cost savings, the truth is more complex. “You’d hope it would be a good time to develop more efficient and affordable systems, but in fact traditional contractors’ prices are coming in more competitively. [The industry] needs more investment to gear up,” says Stuart Piercy of Piercy Connor. James Pickard agrees: “We’re finding tenders are coming in 20% lower than the cost plan. We need some inflation back in traditional construction before offsite becomes more appealing.”
But perhaps this situation can’t prevail much longer. “Prices are being driven down, but in many areas costs are actually going up,” says Sir Robert McAlpine’s Oram. “There’s a tension developing, where tenders aren’t necessarily reflecting costs. It’s unsustainable over anything but the short-term.”
Mark Cammies, property director at Health Properties, agrees: “For the next 18 months or so, contractors might be able to buy work, and clients can squeeze margins to the floor. For some, that might be the right short-term fix. But there has to be a shift. I don’t think the old way of doing things — pushing the subbies to the wall - is a sustainable business model.”
No one is saying that offsite is right for every project. “If a client is looking for prestige, you probably wouldn’t want to offer standard designs,” says Oram. “But if clients are looking for quality and value for money, I think it has a role to play, and it’s certainly an approach we could bring to public sector procurement. “
And Cammies agrees. “There will always be a place for one-off tenders and traditional construction, but most other projects could certainly benefit. But people generally want facts and data. The only way you’ll get take up in the NHS or BSF programmes is to be able to show examples of excellence. When it goes from being theory to reality, that’s when people do bite — even the politicians.”
And, of course, taking offsite and DfM further into public sector education and health territory, could reduced the reinvention of wheels while tax-payers pick up the bill.
Foster's Bath hospital has been "de-constructed" and put back together for 30% less capital cost at Reading (below)
Health properties Management is the development arm of Circle, a company owned by doctors and non-clinical staff that is delivering new hospitals to be used by both private and NHS patients. Its first completed scheme in Bath, designed by Foster & Partners and built by Vinci Construction, was the stand-out healthcare project of 2010: sleek, modern and definitely non-NHS, with a fit-out of public areas and patient rooms that evoked the comfort of Carluccios or Malmaison.
Bath was conceived as the first in a series of hospitals, with architects Hopkins & Partners, BDP and Rogers Stirk & Harbour lined up to take the brand forward. But although Health Properties valued its architects’ creative input, it realised that repeating traditional contracts and site-based methods would build unnecessary cost and time into its repeat programme.
At a BuildOffsite conference in June 2009, it met Bryden Wood, an architect with a specialism in Design for Manufacture and an integrated M&E and structural practice. They set about “de-constructing” Bath: identifying parts of the hospital where offsite efficiences could be found, and splitting them off from aspects that would be bespoke to each site and designed by the architects.
Client and consultant devised the Health Properties “platforms”, as the basis for each facility. Elements such as the structural frame, operating theatres, theatre support rooms, bedrooms and bathrooms will all be highly standardised. The platforms also include minimum and maximum floor-to-ceiling heights and grid spacings, based on the production capability of its manufacturers.
“We’re giving the same pieces of the jigsaw to Hopkins, Rogers and Foster, and they can all use them in a different way,” says Health Properties property director Mark Cammies, whose previous role was programme director at Tesco. “We’ve retained the architects to get a tension between production design and creative design. Somewhere in the middle, we hope you get the solution.”
Bryden Wood director Jaimie Johnstone provides a medical analogy: “People are all different, but at DNA level we’re pretty much the same. So we had to work out how to build the DNA of a hospital, when you can’t play with the major arteries or the spleen, but you can change the personality and style.”
“People think that hospitals are different and complicated, but you just need to be able to understand the components and the kit of parts,” he adds. They identified a hierarchy of patient needs, from services-intensive operating theatres, with their need for scrubbed air and medical gases and sophisticated IT; through to recovery areas, in-patient rooms, offices and catering, and front-of-house atrium and reception.
One key element is the “theatre hood” – a pre-fabricated module that incorporates all the fans, filters, light fittings and anaesthetic gases surgeons need, that will simply be dropped into the standardised ceiling grid above the operating table.
Another key is the compression of services, ceiling voids and floor plenums. Less space for services and structure means less materials and less energy used to condition and heat the air flow, plus a smaller carbon footprint. While Bath attained BREEAM Very Good, Health Properties is aiming for BREEAM Excellent to Outstanding in future. “[Our next hospital at] Reading will be a much leaner building for the same functionality as Bath, “ says Johnstone.
By rationalising and compressing the design, Health Properties is already achieving a 28% cost saving compared to Bath, which cost £3 400 per m2. In comparison, Mark Cammies quotes indicative NHS costs starting at £2 500 per m2 for a health centre with straightforward services, rising to £4 900 per m2 for a PFI hospital currently on site in Hertfordshire.
Meanwhile, Reading has just started a 68 week construction programme, to be followed by a 12 week commissioning process - a total 20% shorter than Bath’s.
Acknowledging that the savings available through procuring a standard “kit of parts” will take longer than one project to realise, it is targeting 40% for its third project in Manchester, designed by Foster & Partners, and the 4th in Birmingham will aim for 50%.
Alan Kondys, framework director for contractor Vinci Construction, said that the key to achieving these will be the confidence of the offsite suppliers, pointing out that cost efficiencies can evaporate if suppliers are pricing for single, one-off contracts.
“There is a lot of enthusiasm from suppliers for long-term multi-project relationships. It’s not the size of the margin that matters, it’s the reliability of the workload. The supply chain will tool up if it has confidence in a meaningful [client] relationship,” he says.
Health Properties believes it can combine offsite production, fantastic architecture and impressive savings. But could a similar approach work in the NHS procurement programme? Cammies says that NHS staff who’ve visited Bath have already been impressed by its value-for-money. But he points out that structural issues in the NHS, with multiple NHS Trusts enjoying considerable autonomy, mitigates against the kind of leadership, upfront investment and shared programme needed. However, he points out that neighbouring Trusts could combine forces to generate economies of scale and follow Health Properties’ lead.
Bryden Wood's EcoCanopy system can provide schools for £1,000 per sqm
Richard Ogden, chairman, BuildOffsite
I have worked in the construction industry for almost 40 years and throughout that time I have been an unapologetic supporter of the proposition that buildings should, as far as possible, be assembled on site from engineered components made in factories. As a client, I did not want to pay for activities endemic within the industry but which delivered not a jot of value. I include material waste, poor productivity and multiple layers of managers supervising the next level down the supply chain – and all claiming to be working to protect the client’s interests.
I can think of no legitimate reason why the construction industry should be any less efficient than the best modern manufacturing sectors. But the industry is for the most part mired in levels of productivity and quality that other industries left behind decades ago. Let’s not forget that it is the client and the end customer who picks up the tab for this inefficiency.
However, it is undoubtedly still the case that most construction in the UK is still being delivered by traditional site based methods. So why am I still making the case for offsite construction to be the norm, and why do I believe that after so many false dawns we are now at the tipping point?
So I am very confident about the future of offsite construction solutions. Indeed I suggest that in a short time, assembly of components on site will be the norm for the majority of new build construction sites. The next challenge will be for the offsite supply side and designers and constructors to demonstrate new offerings that can make the case for on site assembly to deliver major refurbishment projects.