Orange Water and Sewer Authority (OWASA) : Energy performance

Better Buildings, Better Plants Challenge partners strive to decrease source energy use intensity (EUI), and to increase the percent improvement compared to a set baseline year.  As part of the Better Plants Challenge, OWASA has pledged to improve the energy intensity at its 39 facilities by 25% over a 10 year period.  This voluntary pledge aligns with OWASA’s existing commitment to sustainability, which was recognized in 2014, when OWASA received a national award for Sustainable Water Utility Management from the Association of Metropolitan Water Agencies. With an energy intensity improvement of 25% since its baseline year of 2013, OWASA met its 25% reduction in energy intensity target four years earlier than its 2024 target. 

Looking at the percent improvement in energy performance across all facilities can provide insight into how an organization is saving energy. OWASA's 7 facilities are made up by one waste water treatment plant and one water treatment plant, supplemented by a larger number of pumping stations and support facilities. The waste water treatment plant underwent a major renovation to the aeration and mixing system, helping that plant improve its energy intensity by 35%. Since this plant alone represents more than half of OWASA's energy consumption, that renovation has helped OWASA approach their overall energy intensity target.

OWASA calculates energy intensity in terms of source purchased energy consumed (in MMBtus) per million gallons of influent water flow. The percent change in energy intensity is tracked for each facility on both a monthly and annual basis. These metrics are rolled up to the corporate level, with a corporate-wide percent improvement in energy intensity calculated by taking a weighted average of the percent change in energy intensity at the individual facilities.