In the aftermath of the storm, deputy prime minister John Prescott told the Commons that Britain's infrastructure, flood defences and drainage systems needed to be strengthened to cope with the increasingly violent weather associated with global warming.
As 4792 homes lay damaged, the DETR confirmed that a continuing review of the structural regulations, known as Part A, would be refined. A spokesperson for the department says: "Part A is under review. In particular, the provisions for robustness have been revisited to take account of climate change."
Less than a month after the storm, research body the Foundation for the Built Environment published a study called Potential Impact of Climate Change in the Built Environment. The report, part-funded by the DETR, predicted that global warming would lead to a rise in structural problems including subsidence caused by increased soil movement, damage to roofs caused by gales, and the weakening of foundations by underground water.
Next, the DETR commissioned a technical report from BRE on how Part A might be revised to ensure buildings were safe in extreme weather conditions. This study was delivered in January and a spokesperson for the DETR says the consultation document on revisions to Part A will be issued this summer.
BRE scientist Mark Phillipson, co-author of the November report, says data on climate change confirms the need for design changes to new buildings. He says: "We have an increasingly accurate picture of what climate change is going to be like in 20 to 50 years' time, we can see that the safety factor imposed by the Building Regulations will need to be increased."
John Hirst, a structural engineer at Arup, confirms that the design of homes will have to change. He says: "Fundamentally, houses are built to take a storm of the intensity that occurs once every 50 years. If there is now a 2% possibility of that event being exceeded, there is a issue about factors-of-safety". Hirst calls this the "sleep at night factor".
He says the public expect buildings to withstand extreme weather: "People might accept local damage to fixtures and finishes, but they demand – and require – a high standard of safety as regards a building's principal elements.
"It is acceptable that you might have a roof tile come off or even part of the roof, but for a whole building to go is a different matter. If those consequences are to be more prevalent, building standards will have to be increased and designs will need to be more conservative in their safety standards."
If we fail to make the prepare for the future, the BRE report warns that we will be stuck with a legacy of unsellable, uninsurable buildings.
Data in the report was based on research carried out by the UK Climate Impact Programme, which models the impact of climate change on UK regions.
Its predictions include a 370 mm rise in sea level by 2050, a 2.4°C increase in London's average temperature by 2050, a 24% hike in London's winter rainfall by 2080 and a 20% drop in summer rainfall in southern and south-east England by 2080.
Based on these forecasts, BRE makes recommendations on how professionals can adapt building design to minimise wind damage and subsidence in clay soils, limit dampness from rain penetration and prevent weather damage to materials. It also outlines maintenance and refurbishment regimes for existing buildings (see table). The report estimates the increased upfront costs of these safeguards at about £5bn, which it says must be weighed against the expected lifetime of the building and the whole-life costs.
Average increases in wind speed of 6% are likely to cause £1-2bn of damage to 1 million buildings. To reduce the damage, roof fixings should be strengthened for new and existing buildings at an additional cost of £2.5bn a year.
The report also covers windows and ventilation systems. When window frames need replacing, PVCu windows should be used at an estimated extra cost of £2.4bn a year. BRE recommends that natural ventilation or passive cooling systems for buildings be further developed in an effort to reduce the need for air-conditioning. If not, its increased use in hotter summers is expected to absorb most, or all, of the 12-19% energy savings expected from warmer winters – and the energy needed to power those systems will, in turn, add to global warming.
Dry summers could cause a 50-100% increase in subsidence claims in vulnerable areas such as the Thames Valley, Bristol and Birmingham. This may cost £200-400m extra. However, the extra cost of futureproofing buildings in these areas, for example by incorporating concrete raft foundations that allow the house to float on clay ground, would be only £32m. By 2080, driving rain is likely to increase by up to 33% in London and the Home Counties during autumn and winter, affecting up to 7 million dwellings. This will increase the risk of damp in houses with certain types of cladding and insulation-filled cavities.
Not only will building fabric have to be adapted to the new climate, but the construction process, too, will need to change. The report states that higher wind speeds, more storms, higher summer temperatures, increased ultraviolet exposure and more rainfall will increase the dangers of working on site and create storage problems for materials. BRE also proposes that the construction process should be adapted to include increased prefabrication and off-site assembly.
Stephen Garvin at BRE's East Kilbride laboratory says the industry must look at design issues and implement simple measures. "If materials degrade faster in extreme weather, structural stability may be compromised. Our intention is not to come down against any particular material or technique but to make sure that we build the right way so the impact of climate change is reduced."
He adds: "Insuring the quality of construction and the durability of materials under potentially aggressive conditions may be more costly.
But it is as much about improving the quality of construction as changing the way we build."
For the industry and the DETR, there are stormy times ahead.
The 30-second guide to Part A: StructuresPart A covers the strength and stability of buildings. It provides guidance on the cladding, roofing, structure and foundations of all building. A second section deals with “disproportionate collapse”. Part A is under review, with the consultation due to be issued this summer. The Approved Document, which gives technical details of complying with the rules, does the following jobs:
- Covers the structural design of houses, including foundations, wall construction, the number and size of permitted openings and chimneys
- Provides guidance on heavier types of cladding and curtain walling
- Deals with re-roofing and gives guidance on how to assess whether a roof replacement constitutes a material alteration
- Lists reference sources on ground instability
- Section A3 contains guidance designed to reduce the possibility of the disproportionate collapse of buildings of five storeys or more. It was introduced after the collapse of Ronan Point tower in 1968.