Understanding Demand Reductions Related to Increased Use of HE Products


  • Lisa R. Krentz - Hazen and Sawyer
  • David Bracciano - Tampa Bay Water

Hazen and Sawyer has provided a variety of water supply reliability planning and forecasting services to Tampa Bay Water.

Tampa Bay Water, a regional water supply wholesaler, provides water to six member governments serving a population of approximately 2.3 million people in the Tampa Bay region. The agency’s 2013 Demand Management Plan (DMP) update includes an evaluation of potential demand management as a beneficial tool for long-term water supply planning. The results define how passive or active implementation of demand management activities fit into Tampa Bay Water’s long-term water supply planning process, including supply reliability and member government long range demand projections.

A key objective of the DMP was to reflect improvements in the state of knowledge of water use efficiency occurring since 1995. The U.S. Energy Policy Act of 1992 (EPAct), effective in 1994, was responsible for mandating flow standards for many fixtures (e.g., toilets, faucets and showerheads). Since that time, manufacturers have continually introduced and marketed fixtures and appliances, exceeding EPAct standards and reducing water consumption. This led to programs such as EnergyStar and EPA WaterSense, which requires independent third-party certification of performance and product durability, insuring product use is consistent with labeling over a defined life. WaterSense product certification ensures performance at rates lower than the current national efficiency standards while meeting consumer expectations, and influencing the market penetration of high-efficiency (HE) products.

As part the DMP update, passive demand reductions were estimated through the 2035 demand forecast planning horizon. Using parcel data and end-use analysis, water savings associated with natural (passive) replacement of specific water-efficient technologies were
determined. Water savings are estimated based on changing water-use intensities across time and technology compared to the current use of water-efficient technologies. Parcel data and the end-use analysis provide estimates of the current level of penetration of existing water efficient technologies. The distribution of fixture age/efficiency in region was estimated using local property appraiser data, and projections of HE fixture market penetration rates used to estimate the rate of change and impact an evolving HE market is expected to have on future demands.

As consumers decide to purchase and install HE water products, water consumption efficiency increases. Tampa Bay Water’s baseline demand forecast reflected water use of existing HE products within sectoral per account water use calculations, but did not take into account increased penetration of high-efficiency products. By estimating the distribution of differing water-use intensities across time and technologies, baseline forecasts were adjusted to reflect demand reductions likely to passively occur. This paper explores the implications associated with forecasting long term demands inclusive of increasing passive penetration rates associated with high efficiency products compared to commonly used planning forecast methods.

For more information, please contact the author at lkrentz@hazenandsawyer.com.

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