Designing for sustainable water use

Buildings and neighbourhoods need to use water more efficiently.

Photo by CABE / Anne Woods

Neighbourhood and site masterplans are critical to the process of sustainable water management. As well as guiding the major development of residential, commercial and industrial areas over long periods of design and construction, they provide a critical chance to organise development so that sustainable water management infrastructure is given enough suitable space to operate effectively.

They should integrate water-sensitive design principles and concept plans for:

• landscape/green infrastructure and open space systems
• street layout and design
• major stormwater systems/SUDS
• site planning
• building design

Key design actions at the neighbourhood and site scale include:

• designing public space so that the planting takes surface water into account and maximises natural irrigation
• integrating permeable paving so that hard standing contributes to the drainage performance of the site
• identifying, conserving, restoring and enhancing natural features, including the network of culverted water-courses, channelised streams and rivers
• maximising the role of soft landscaping in supporting drainage and water retention for example through the use of grass swales to facilitate water infiltration
• establishing a network of gutters, water butts and passive garden irrigation systems.

In choosing planting it is important to understand the requirement to keep green areas well irrigated. Evapotranspiration from all living green material helps to reduce temperatures and counter the urban heat island effect. However, this only works if the green areas are kept green. Otherwise, at exactly the time that the evapotransporation effect is needed most, it fails.

If our grass surfaces dry out and turn brown in times of drought they will function very much like hard, non-porous surfaces, exhibiting no temperature difference and becoming part of the heat island.

At the building scale, wherever possible roof water and cleaned run-off collected from permeable surfaces should be collected and stored for non-potable uses in buildings and surrounding green spaces. Consideration should be given to local treatment of black and grey water for re-use or for wetland and planting recharge and irrigation. This process will also balance the capture of rainfall for non-potable use. Such considerations should be incorporated into planning guidance documents which support Local Development Frameworks, and will be increasingly required by Building Regulations as part of the adoption of the Code for Sustainable Homes.

Water efficiency devices should also be designed in to the building. These include low flow fixtures, flow restrictors, dual flush toilets and water efficient appliances. Such devices can also be easily retro-fitted into existing homes and buildings. For details on fixtures see the Waterwise website.

Priority: encourage sustainable water use
Tags: water, neighbourhoods, buildings and spaces