It makes perfect sense to do away with the mess, bother and lead times of traditional building methods and embrace the emerging world of off-site manufacture, but is it a safe option? For prefabricated buildings to make a significant impact on our built environment, the concept must first be proven to present reliable solutions.
After all, many of us grew up with the view that prefabs were sub-standard buildings. We knew of damp community halls, musty classrooms and cold prefab houses that had outlived their original design life and were literally rotting from the ground up.
Over 150,000 prefab buildings were put up at a cost of £2m in the difficult years following the war, when urgent need for housing dictated the need for speed. Surprisingly however, prefabs were not necessarily cheaper than traditional buildings, with many types embodying the latest technology including electricity and central heating, contemporary fitted kitchens and modern bathrooms. In fact, the average cost of a prefab was twice that of a terraced house – but at the time such spending was necessary for the authorities to meet their needs.
It is apparent to us now that the key weakness of prefabs was down to damp, which caused unhealthy mould growth and rot. These failings can mostly be traced to failed damp-proofing and insufficient insulation. However, flaws in the design cannot usually be held responsible, as generally the design life of a prefab was only 10–20 years.
Fast-forward to today, and we again find ourselves with a serious housing shortage, and as before, the government is encouraging the uptake of buildings constructed off-site or using off-site manufactured components to guarantee quality and decrease lead times and cost. The new industry government expert Off Site Construction Group announced recently by Housing Minister, Max Prisk, will seek to use off-site construction to ‘revolutionise the way we deliver our housing, providing a swift, high quality solution to creating cost effective, zero carbon homes’ [i]
How can you produce a building that can be adapted to a wide range of uses and still be as green as possible? It was still a question designer and furniture maker Philip Clayden was asking himself a few years ago when he received some funding to work at Oxford Institute for Sustainable Development, Oxford Brookes University.
‘The project was to make a modular building that was quick to assemble and kept costs down. We developed a “fuselage” type structure and produced a prototype building which is now in London.’
He describes it as a ‘hybrid’ using elements of traditional construction combined with more green building materials. But the thinking accelerated when Mr Clayden, 46, met 51 year old Oxford-based entrepreneur Jonathan Finnerty who was looking for a his next project and somewhere to develop his passion for the environment.
He added ‘When we started talking we realised we wanted to go beyond building regulations and the code for sustainable homes. We wanted to future proof the design.’
Trees cover approximately 50% of Europe’s land area and absorb about 10% of the EU’s greenhouse gas emissions according to recent reports. This natural form of carbon capture is critical as part of the European commitment to alleviate the impact of climate change. However, large swathes of European forest are more than 70–80 years old, and by reaching that age growth slows down and with that their ability to maintain an effective carbon sink. Perhaps we should now not only be increasing the amount of land dedicated to forestry but also replacing old trees for new – this would have to be done selectively and sensitively in order to minimise the impact on biodiversity.
The second generation version of the arc-haus, which has been in prototype development at Green Unit’s South Oxfordshire factory for the past twelve months, has been built according to Passivhaus principles. BRE have now been engaged to take the company through the process of Passivhaus certification.
Sustainable building practices are essential in stimulating and maintaining the growth of eco-friendly and energy efficient architecture. Of course, the materials used for construction need to be sustainable. But how do we identify sustainable materials?