Water Efficiency

BedZed, UK. Rainwater collection for reuse within the building

The target reduction in water use for the new development is 75% compared to the pervious building. This equates to minimum of 8kL per person per annum. A higher target may be achieved if economically justified over a 15 year period.

Water use has received less attention in the context of Green buildings than energy use. Part of the reason is that energy is perceived as a non-renewable resource while water is perceived as renewable. However, the quantity and quality of water is increasingly a concern as growing population and development pressures this vital resource. Discussed below are strategies to lessen the demand for water and its associated infrastructure.

In buildings, water is required for potable (taps, kitchens, showers, fountains) and non-potable (toilets, urinals, irrigation) purposes. A further consequence is that water run off from, footpaths, building roofs etc do not detain rainwater.

When considering the water efficiency design the following should be considered:

• Water Efficient Appliances
• Metering/Verification

Water Efficient Appliances

Areas such as irrigation, urinals, Water Closets (WC) and other high use areas must be targeted for careful study. Water saving devices on outlets, infrared flush or manual flush for urinals, low capacity flushing cisterns for WC’s, drip feed irrigation and mulch covering for garden beds, should enable water saving plans that offer considerable savings.

Regular maintenance management systems in place to examine and repair the water supply system. Areas for particular attention would be:

• Leaking taps on both hot and cold services.
• Cistern rubbers causing continuous running water in WC and urinals.
• Pressure lever valves on hot water tanks.
• Ball valves on storage tanks.
• Leaking joins and pipework especially in concealed spaces.
• Thermostatic mixing valves.
• Pressure limiting valves.
• Worn water saving devices.
• Leaking storage tanks such as heaters.
• Uninsulated hot water pipework and equipment.
• Continuously running pressure pumps.
• Diaphragms in pressure vessels.
• Use of cold water where hot water is being used.
• Economic usage of water consuming appliances.
• Develop an economic use of water management system.
• Replace worn fixtures with AAA rated water wise fittings.

Metering/Verification

The conservation of water begins with an investigation into the required use of all systems within a building. Particular attention should be made to observe the habits and consumption requirements of the occupants.

Authority supplied water can be metered to obtain point of use consumption requirements and comparisons should be made with calculated use.

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