Methodology for the National Water Savings and Spreadsheet: Indoor Residential and Commercial/Institutional Products, and Outdoor Residential Products
This report describes the analytical models Lawrence Berkeley National Laboratory (LBNL) developed to estimate impacts of the U.S. Environmental Protection Agency’s (EPA’s) WaterSense® labeling program. The models assess national impacts for WaterSense labeled toilets, faucets, faucet aerators, showerheads, flushing urinals, commercial pre-rinse spray valves, and weather or soil moisture sensor-based irrigation controllers (WBICs) by analyzing national inputs for water use in residential and commercial/institutional (CI) markets. For irrigation controllers, LBNL’s methodology also incorporates a scenario that evaluates impacts in three key large states that are considered to be the principal market for “smart” irrigation controllers: California, Florida, and Texas. The models estimate impacts for the water savings attributable to the program and the net present value (NPV) of the lifetime water savings from more efficient products.
LBNL developed the mathematical models to quantify the water and monetary savings attributable to the WaterSense labeling program for both indoor and outdoor products. The National Water Savings (NWS) models are spreadsheet tools with which the EPA can evaluate the success of its WaterSense program, which encourages buyers to purchase more efficient water-using products. WaterSense labeled indoor products include toilets, faucets, showerheads, and faucet aerators for the residential sector; and flushometer valve toilets, urinals, and pre-rinse spray valves for the CI sector. The current single WaterSense labeled outdoor product is the weather-based irrigation controller (WBIC). It should be noted that other than irrigation controllers, EPA has only considered labeling products that have an efficiency level set by the Energy Policy Act of 1992 (or 2005 in the case of pre-rinse spray valves). EPA places its WaterSense label on products that are more efficient than the federal standards and meet a set of technical specifications for efficiency and performance. The NWS models forecast the amount of water that will be consumed by the residential and CI sectors that do and do not use WaterSensel-labeled products