Green thinking - Skanska

New ways to conserve water 43In a world of water shortages,why use drinking water to flushthe toilet?Seeing Earth from space, you might think there’s plenty of water. But ifyou were to collect all the water on the planet, every little drop of it,including the water in the atmosphere and in the glaciers, into one bigdrop, it would only be as big as you see to the left. The majority of thewater on Earth, 97 percent, is in the oceans, while an additional two percentis frozen in the ice caps and glaciers. Only a fraction is available asa supply for drinking water, which is already in short supply in manyparts of the world.The problem will only get bigger as the planet’s population grows,and the effects of climate change become more apparent. In areas alreadyshort on water, the situation will worsen. Other parts of the world, suchas Western and Central Europe and the US, will experience insufficientsupplies.We have to start saving water and using it more wisely.By installing water-saving appliances, consumption can be radicallyreduced. Another way to reduce water use is recycling – for example,redirecting water from sinks and showers to flush toilets. In large buildings,purification systems make it possible to reuse even very dirtywater. Collected rainwater can also be used in buildings, or for gardenirrigation.In addition to conserving water, we need to manage stormwater andpreserve, or even enhance, biodiversity in critical areas like wetlands.Green roofsGreen roofs have plants growing onthem that are specifically designed intothe construction when the project isbeing developed. This is yet anotherexample of a robust, technically simplesolution with several advantages.Green roofs absorb rainwater andreduce runoff by up to 85 percent,reducing the risk of flooding. Plantsand the underlying soil layer filter outimpurities from the water, so that whatdoes run off is cleaner. The technologycan be combined with basins to collectthe water for reuse in the building oroutside. The green plants absorb impuritiesfrom the air as well.Green roofs also provide better insulation– and unlike traditional roofingmaterials such as tin, concrete or tiles,green roofs do not reradiate heatto urban areas. They also enhance localbiodiversity by providing attractivevegetation for wildlife.Sustainable drainagesystemsConventional drainage systems divertthe runoff water into a network ofpipes. This can lead to local and downstreamflooding – not to mentionthe fact that stormwater is often contaminatedwith pollution from urbansurfaces.By contrast, sustainable drainagesystems can reduce the quantity of runoffwhile reducing pollution. Thesesystems promote natural drainage, filtrationand biological treatment processes.By allo wing water to penetratethe ground, sustainable drainagereplenishes groundwater supplies.Some solutions can also enhance orprovide habitats for wildlife.On a new school campus in the UK,a sustainable drainage system hasensured that site discharge is approximately35 percent lower followingconstruction, despite an increase in theextent of impermeable surfacing.