Britain now uses more energy to cool buildings in the summer than to heat them in the winter. As urban areas get hotter, more cramped and polluted, the green roof idea starts to make sense.
Green roofs have vegetative layers that absorb CO2 emissions. Rooftop soil and plants - from simple sedums and mosses to bigger shrubs and even trees - have insulating properties that greatly reduce the heating and cooling costs of a building. This technique has been helping Africans to cool down and Scandinavians to keep warm for years. It cools the air, filters pollution, dampens noise - and promotes biodiversity. And, according to the independent Green Roof Centre, it absorbs up to 75% of rainwater, which reduces runoff, preventing flash floods. So why aren't green roofs sprouting everywhere? Germany introduced the idea in the '60s, and 10% of its roofs have now been converted, backed by government grants. The idea has been slow to take root here. Ken Livingstone described roofs as 'London's most under-used asset', but he's still working out how to turf The Gherkin. A green roof costs between £60 and £140 per sq m and involves structural and maintenance considerations, so seek advice before calling in the hoe-wielders. Imagine the benefits to staff, customers and neighbours.
GREENIE POINTS (OUT OF 10)
NINE - it's a big investment, but think of the garden parties ...
- Dave Waller is MT's resident eco-propagator.