Tag Archives: living roofs

Me and my rocket-launcher

Ten years ago I was asked by English Nature to survey some of London’s newfangled ‘green’ roofs, to see whether they really were good for wildlife. I was really quite chuffed to be asked, it was a prestigious piece of work.

Egged on by the supporters of German and Swiss planning laws, having a living roof on top of new buildings was increasingly seen as a way of mitigating for any wildlife loss from the flowery, but often ugly, brownfield sites as they were developed. This was good for the developers, who could claim environmental credentials, good for the planners, who could claim environmental commitment, but was it good for the insects?

I took to the rooftops to find out. Most of the roofs were small, a couple of private houses, the visitor centre of the Mile End Cemetery Park, and a community centre on Gray’s Inn Road. But one series were huge — on several of the office blocks at Canary Wharf. These were also the most difficult to survey. Unlike some of the smaller buildings, which had soil/gravel mixtures and which produced a lush flowery growth to attack with a sweep-net, those at Canary Wharf were covered with a low carpet of drought-hardy Sedums, the stonecrops you might have found on slightly old-fashioned rock gardens.

Sedum at Canary Wharf, a red/green carpet for the delight of office workers looking down from above.

Carpet is the right word. Huge mats of spongy rubber, a bit like those used in the gym, were impregnated with Sedum seeds, then grown out of doors. When required, they were rolled up, delivered on site in giant rolls and cut to fit just like someone carpeting the lounge.

From the offices above, they presented a red/green pattern against the concrete, steel and glass. But they were only a few centimetres thick. My sweep-net was set aside, what I needed here was something a bit more high-tech. The B&Q on the Greenwich Peninsula provided the answer — a two-stroke garden blower-vac.

Fixing a stout canvas bag into the intake nozzle, I could use it like a giant hoover, sucking up any bugs from the short sward, then turning it off and emptying the bag contents onto a plastic sheet. It worked well, and I found plenty of odd and unusual things. My draft report is here.

There was, however, always something on my mind. Here was I, in a major financial district of the capital, in the shadow of some of Britain’s tallest buildings, a few months after the World Trade Center attacks, carrying something that looked like a rocket launcher.

Hoovering the roof.

I don’t know how many people noticed me out of the windows of 1 Canada Square, but I’m extremely thankful I was never confronted by the anti-terrorist squad.