| water metering | water meters are often fitted for free and can increase awareness of water usage |
| watt | a unit of power measuring the rate of flow of electricity |
| wattle and daub | a woven willow or hazel framework (wattle) is then daubed with a daub plaster mixture of earth and dung and sometimes horse hair. used as infill in a timber framed building. |
| weatherstripping | thin strips of metal, rubber, vinyl or foam around doors and windows that prevent infiltration of air or moisture. |
| wetlands and ponds | these can be particularly beneficial during heavy rain due to their capacity to hold large amounts of water and therefore reduce flood risk and are best suited to larger sites where they can be incorporated into landscaping schemes. ponds and wetlands also help with grit removal. algae and plants in wetlands can significantly assist with filtering and nutrient removal. |
| whole-of-life cost | the integration of life cost analysis and life cycle assessment and analysis in project planning, assessment, design and management decisions, so that all economic and environmental costs and considerations are integrated into decision-making processes. |
| wind turbine | machine for generating electricity from the wind. |