Water use is benchmarked using EPA’s Portfolio Manager.
Portfolio Manager tracks water meters based on the water source. There are four types of water meters available:
- Municipally Supplied Potable Water – Water that is of sufficient quality for human consumption and that is obtained from public water systems that are classified, permitted, and approved for human consumption.
- Municipally Supplied Reclaimed Water – Wastewater treatment plant effluent purchased from a public water system, which has been diverted for beneficial uses, such as irrigation, that substitute the use of an existing freshwater source.
- Alternative Water Generated On-Site – Water that is not obtained from a surface water source, groundwater source, nor purchased reclaimed water from a third party. It can include rainwater or stormwater harvested onsite, sump pump water harvesting, gray water, air-cooling condensate, reject water from water purification systems, water reclaimed onsite, or water derived from other water reuse strategies.
- Other Water Sources– Water that is obtained from natural freshwater sources that are not municipally supplied (including surface and groundwater systems such as onsite wells, lakes, streams, etc.), and any other water source not fitting one of the above categories.
Water use is measured in gallons. This data comes from water bills that are entered in Portfolio Manager. The calculated number of gallons used is then divided by the building’s square footage. The result is the building’s Water Use Intensity (WUI).
To calculate the water percentage difference over the competition year, WUI from the previous year is subtracted from the WUI of the current year. The calculated difference is how we determine the biggest loser.
WUI = gallons/square footage
Current Year – Prior Year = % lost or gained