WaterSense Program: Methodology for National Water Savings Analysis Model Indoor Residential Water Use

The U.S. Environmental Protection Agency (EPA) influences the market for plumbing fixtures and fittings by encouraging consumers to purchase products that carry the WaterSense label, which certifies those products as performing at low flow rates compared to unlabeled fixtures and fittings. As consumers decide to purchase water-efficient products, water consumption will decline nationwide. Decreased water consumption should prolong the operating life of water and wastewater treatment facilities.This report describes the method used to calculate national water savings attributable to EPA?s WaterSense program. A Microsoft Excel spreadsheet model, the National Water Savings (NWS) analysis model, accompanies this methodology report. Version 1.0 of the NWS model evaluates indoor residential water consumption. Two additional documents, a Users? Guide to the spreadsheet model and an Impacts Report, accompany the NWS model and this methodology document. Altogether, these four documents represent Phase One of this project. The Users? Guide leads policy makers through the spreadsheet options available for projecting the water savings that result from various policy scenarios. The Impacts Report shows national water savings that will result from differing degrees of market saturation of high-efficiency water-using products.This detailed methodology report describes the NWS analysis model, which examines the effects of WaterSense by tracking the shipments of products that WaterSense has designated as water-efficient. The model estimates market penetration of products that carry the WaterSense label. Market penetration is calculated for both existing and new construction. The NWS model estimates savings based on an accounting analysis of water-using products and of building stock. Estimates of future national water savings will help policy makers further direct the focus of WaterSense and calculate stakeholder impacts from the program.Calculating the total gallons of water the WaterSense program saves nationwide involves integrating two components, or modules, of the NWS model. Module 1 calculates the baseline national water consumption of typical fixtures, fittings, and appliances prior to the program (as described in Section 2.0 of this report). Module 2 develops trends in efficiency for water-using products both in the business-as-usual case and as a result of the program (Section 3.0). The NWS model combines the two modules to calculate total gallons saved by the WaterSense program (Section 4.0). Figure 1 illustrates the modules and the process involved in modeling for the NWS model analysis.The output of the NWS model provides the base case for each end use, as well as a prediction of total residential indoor water consumption during the next two decades. Based on the calculations described in Section 4.0, we can project a timeline of water savings attributable to the WaterSense program. The savings increase each year as the program results in the installation of greater numbers of efficient products, which come to compose more and more of the product stock in households throughout the United States

A Systems Framework for Assessing Plumbing Products-Related Water Conservation

Reducing the water use of plumbing products—toilets, urinals, faucets, and showerheads —has been a popular conservation measure. Improved technologies have created opportunities for additional conservation in this area. However, plumbing products do not operate in a vacuum. This paper reviews the literature related to plumbing products to determine a systems framework for evaluating future conservation measures using these products. The main framework comprises the following categories: water use efficiency, product components, product performance, source water, energy, and plumbing/sewer infrastructure. This framework for analysis provides a starting point for professionals considering future water conservation measures to evaluate the need for additional research, collaboration with other standards or codes committees, and attachment of additional metrics to water use efficiency (such as performance)

Review of Literature for Inputs to the National Water Savings Model and Spreadsheet Tool-Commercial/Institutional

Lawrence Berkeley National Laboratory (LBNL) is developing a computer model and spreadsheet tool for the United States Environmental Protection Agency (EPA) to help estimate the water savings attributable to their WaterSense program. WaterSense has developed a labeling program for three types of plumbing fixtures commonly used in commercial and institutional settings: flushometer valve toilets, urinals, and pre-rinse spray valves. This National Water Savings-Commercial/Institutional (NWS-CI) model is patterned after the National Water Savings-Residential model, which was completed in 2008. Calculating the quantity of water and money saved through the WaterSense labeling program requires three primary inputs: (1) the quantity of a given product in use; (2) the frequency with which units of the product are replaced or are installed in new construction; and (3) the number of times or the duration the product is used in various settings. To obtain the information required for developing the NWS-CI model, LBNL reviewed various resources pertaining to the three WaterSense-labeled commercial/institutional products. The data gathered ranged from the number of commercial buildings in the United States to numbers of employees in various sectors of the economy and plumbing codes for commercial buildings. This document summarizes information obtained about the three products' attributes, quantities, and use in commercial and institutional settings that is needed to estimate how much water EPA's WaterSense program saves

IMPROVING ENERGY EFFICIENCY AND REDUCING COSTS IN THE DRINKING WATER SUPPLY INDUSTRY: An ENERGY STAR Resource Guide for Energy and Plant Managers

As American drinking water agencies face higher production costs, demand, and energy prices, they seek opportunities to reduce costs without negatively affecting the quality of the water they deliver. This guide describes resources for cost-effectively improving the energy efficiency of U.S. public drinking water facilities. The guide (1) describes areas of opportunity for improving energy efficiency in drinking water facilities; (2) provides detailed descriptions of resources to consult for each area of opportunity; (3) offers supplementary suggestions and information for the area; and (4) presents illustrative case studies, including analysis of cost-effectiveness

National and Regional Water and Wastewater Rates For Use inCost-Benefit Models and Evaluations of Water Efficiency Programs

Calculating the benefits and costs of water conservation orefficiency programs requires knowing the marginal cost of the water andwastewater saved by those programs. Developing an accurate picture of thepotential cost savings from water conservation requires knowing the costof the last few units of water consumed or wastewater released, becausethose are the units that would be saved by increased water efficiency.This report describes the data we obtained on water and wastewater ratesand costs, data gaps we identified, and other issues related to using thedata to estimate the cost savings that might accrue from waterconservation programs. We identified three water and wastewater ratesources. Of these, we recommend using Raftelis Financial Corporation(RFC) because it: a) has the most comprehensive national coverage; and b)provides greatest detail on rates to calculate marginal rates. The figurebelow shows the regional variation in water rates for a range ofconsumption blocks. Figure 1A Marginal Rates of Water Blocks by Regionfrom RFC 2004Water and wastewater rates are rising faster than the rateof inflation. For example, from 1996 to 2004 the average water rateincreased 39.5 percent, average wastewater rate increased 37.8 percent,the CPI (All Urban) increased 20.1 percent, and the CPI (Water andSewerage Maintenance) increased 31.1 percent. On average, annualincreases were 4.3 percent for water and 4.1 percent for wastewater,compared to 2.3 percent for the All Urban CPI and 3.7 percent for the CPIfor water and sewerage maintenance. If trends in rates for water andwastewater rates continue, water-efficient products will become morevaluable and more cost-effective

Saving Water Saves Energy

Hot water use in households, for showers and baths as wellas for washing clothes and dishes, is a major driver of household energyconsumption. Other household uses of water (such as irrigatinglandscaping) require additional energy in other sectors to transport andtreat the water before use, and to treat wastewater. In California, 19percent of total electricity for all sectors combined and 32 percent ofnatural gas consumption is related to water. There is a criticalinterdependence between energy and water systems: thermal power plantsrequire cooling water, and water pumping and treatment require energy.Energy efficiency can be increased by a number of means, includingmore-efficient appliances (e.g., clothes washers or dishwashers that useless total water and less heated water), water-conserving plumbingfixtures and fittings (e.g., showerheads, faucets, toilets) and changesin consumer behavior (e.g., lower temperature set points for storagewater heaters, shorter showers). Water- and energy-conserving activitiescan help offset the stress imposed on limited water (and energy) suppliesfrom increasing population in some areas, particularly in drought years,or increased consumption (e.g., some new shower systems) as a result ofincreased wealth. This paper explores the connections between householdwater use and energy, and suggests options for increased efficiencies inboth individual technologies and systems. Studies indicate that urbanwater use can be reduced cost-effectively by up to 30 percent withcommercially available products. The energy savings associated with watersavings may represent a large additional and largely untappedcost-effective opportunity

Community Code Verification Exercise for Simulating Sequences of Earthquakes and Aseismic Slip (SEAS)

Numerical simulations of sequences of earthquakes and aseismic slip (SEAS) have made great progress over past decades to address important questions in earthquake physics. However, significant challenges in SEAS modeling remain in resolving multiscale interactions between earthquake nucleation, dynamic rupture, and aseismic slip, and understanding physical factors controlling observables such as seismicity and ground deformation. The increasing complexity of SEAS modeling calls for extensive efforts to verify codes and advance these simulations with rigor, reproducibility, and broadened impact. In 2018, we initiated a community code‐verification exercise for SEAS simulations, supported by the Southern California Earthquake Center. Here, we report the findings from our first two benchmark problems (BP1 and BP2), designed to verify different computational methods in solving a mathematically well‐defined, basic faulting problem. We consider a 2D antiplane problem, with a 1D planar vertical strike‐slip fault obeying rate‐and‐state friction, embedded in a 2D homogeneous, linear elastic half‐space. Sequences of quasi‐dynamic earthquakes with periodic occurrences (BP1) or bimodal sizes (BP2) and their interactions with aseismic slip are simulated. The comparison of results from 11 groups using different numerical methods show excellent agreements in long‐term and coseismic fault behavior. In BP1, we found that truncated domain boundaries influence interseismic stressing, earthquake recurrence, and coseismic rupture, and that model agreement is only achieved with sufficiently large domain sizes. In BP2, we found that complexity of fault behavior depends on how well physical length scales related to spontaneous nucleation and rupture propagation are resolved. Poor numerical resolution can result in artificial complexity, impacting simulation results that are of potential interest for characterizing seismic hazard such as earthquake size distributions, moment release, and recurrence times. These results inform the development of more advanced SEAS models, contributing to our further understanding of earthquake system dynamics

Community Code Verification Exercise for Simulating Sequences of Earthquakes and Aseismic Slip (SEAS)

Numerical simulations of sequences of earthquakes and aseismic slip (SEAS) have made great progress over past decades to address important questions in earthquake physics. However, significant challenges in SEAS modeling remain in resolving multiscale interactions between earthquake nucleation, dynamic rupture, and aseismic slip, and understanding physical factors controlling observables such as seismicity and ground deformation. The increasing complexity of SEAS modeling calls for extensive efforts to verify codes and advance these simulations with rigor, reproducibility, and broadened impact. In 2018, we initiated a community code‐verification exercise for SEAS simulations, supported by the Southern California Earthquake Center. Here, we report the findings from our first two benchmark problems (BP1 and BP2), designed to verify different computational methods in solving a mathematically well‐defined, basic faulting problem. We consider a 2D antiplane problem, with a 1D planar vertical strike‐slip fault obeying rate‐and‐state friction, embedded in a 2D homogeneous, linear elastic half‐space. Sequences of quasi‐dynamic earthquakes with periodic occurrences (BP1) or bimodal sizes (BP2) and their interactions with aseismic slip are simulated. The comparison of results from 11 groups using different numerical methods show excellent agreements in long‐term and coseismic fault behavior. In BP1, we found that truncated domain boundaries influence interseismic stressing, earthquake recurrence, and coseismic rupture, and that model agreement is only achieved with sufficiently large domain sizes. In BP2, we found that complexity of fault behavior depends on how well physical length scales related to spontaneous nucleation and rupture propagation are resolved. Poor numerical resolution can result in artificial complexity, impacting simulation results that are of potential interest for characterizing seismic hazard such as earthquake size distributions, moment release, and recurrence times. These results inform the development of more advanced SEAS models, contributing to our further understanding of earthquake system dynamics