Will climate change threaten warehouse design?

Will climate change threaten warehouse design?
Modern warehouses are still being built to cope with yesterday’s weather patterns. But with the effects of climate change already upon us, Edward Joslin of warehouse and distribution property specialist sbh argues that we should be designing structures able to cope with the future - not with the past.

Every week brings new evidence that weather patterns are changing and will continue to do so, bringing more extreme conditions even to the placid UK climate. Snow may soon be almost unknown in much of the country and 2007 has already brought exceptionally dry and wet spells, confirming the forecast trend to more extreme weather behaviour.

The typical warehouse is still designed with sloping roofs to cater for heavy snowfalls, with roof tie construction techniques that may be vulnerable to high winds, and with guttering and drainage systems unable to cope with sudden, very heavy downpours. With increased pressure on commercial and industrial land, the temptation to develop on areas prone to flooding will grow, so the likelihood of finding warehouse stock under water will increase still further.

The most important first step is to review water capture and drainage systems to ensure that anticipated volumes of rainfall can drain into the main watercourse without backing up and causing flooding. While the record rainfall of more than an inch in five minutes recorded in Yorkshire in 2003 may not be repeated, what were exceptionally heavy falls are becoming increasingly common. Gutters face the first onslaught and overflow, overloading soakaways. Balancing ponds have limited capacity and systems will need larger bore outlets than before to enable water to flow through the system and into the watercourse without flooding.

The trend towards ever-larger warehouses, now nudging a million square feet, could generate further problems. Huge volumes of rain join run-off from hard standing surfaces large enough to provide record levels of parking for HGVs and cars. Surface water drainage systems installed decades before will have little chance of coping, resulting in both vehicle parks and the warehouse itself going under water.

The use of Grasscrete which provides hard standing but allows rain to soak away directly into the soil, may help to mitigate the worst effects of heavy rain. However as they are generally covered by vehicles its likely that grass will not grow and leave a rather unsightly surface. Alternatively pea shingle mixed with Grasscrete may be a solution.

In the longer term, landscaping the site with trees will help to absorb moisture from the ground, ensuring that the soil is able to initially take up more rain than before, easing pressure on soakaways.

While peak wind speeds have not increased over the past few years, their frequency appears to be greater, as the recent UK storms show. While roofing panels and materials, designed to withstand heavy snowfalls, are not vulnerable, traditional fixing methods may no longer be sufficient to hold them in place during high winds. When the wind manages to lift a panel even slightly, it creates the same type of lift as airflow generates on an aircraft wing, forcing the material away from its moorings. Once one section of roof has lifted, those around it are at risk, and it takes little time for a large part of the roof to be exposed to both wind and rain.

Developing structures able to withstand more extreme weather conditions may also impact on other vital issues such as energy efficiency of the materials used, insulation and of course cost. As a leading designer and project-manager of warehousing – including one of the UK’s tallest, a 40m facility for Kimberly-Clark - sbh has unrivalled experience of the challenges facing the occupier or developer, and continues to be at the forefront of the latest relevant issues, technologies and legislation.”

June - 2007