Green Roofs & Rainwater Harvesting

With weather becoming more extreme within the UK, and rainfall up 20% from that recorded a century ago, is it time to think about what can be done within our new and existing architecture to help combat flooding.

On a large scale Sustainable Drainage Systems (SuDS) can be implemented to help provide an alternative to the direct channelling of surface water through a network of pipes. SuDS aim to reduce surface water flooding by mimicking natural drainage regimes – This is achieved by lowering flow rates and increasing water storage capacity.

Looking at buildings, we can slow the rate of rainwater runoff from roofs with the use of Green Roofs. Effectively a living green roof is covering the roof with an absorbent layer. A typical green roof build up consists of standard waterproofing, a drainage layer and a layer of growing medium which the planting grows into. A green roof may also include a water retention layer to support the plants during a period of dry weather.

Green roofs have more use than just rainwater management, its benefits also include: Creating wildlife habitat, Absorbing greenhouse gasses, Insulating the building against heat, cold and noise and Extending the life of the waterproofing. Many buildings in the UK could be retro-fitted with a green roof for a reasonable price and could add value to the building.

If looking at a new build then rainwater harvesting can be easily implemented via a tank which, depending on size can be buried or left on show. Much of the water we use does not need to be of drinking quality – At home and whilst at work we flush toilets, wash vehicles and clothes and water gardens. Rainwater Harvesting is a very simple process; rather than the rain running off the roof, into the gutter and into the drainage system the tank will catch, filter and store this water for non drinking uses allowing us to make use of surface water before it taking up valuable space in our sewer systems.