Objective: To develop data and tools that quantify performance of premise plumbing systems in high-performance buildings, and to support the development of building water efficiency standards and codes.
What is the technical idea? Building designers and standards makers have traditionally focused on energy efficiency when developing high performance building standards and codes. There has been more activity to incorporate water metering and conservation into these codes and standards (e.g., ICC Plumbing and Mechanical Code, IAPMO Green Plumbing Code, ASHRAE Standard 191P). Buildings are being designed with features such as using efficient water heating appliances, low-flow fixtures, and efficient landscape water use. Water labeling of residential buildings, such as EPA’s WaterSense Labeled Homes program and the proposed RESNET HERSH2O program, are gaining traction as well. On the other hand, minimal water use has also had unexpected consequences in premise plumbing systems. Institutions such as the EPA have stated lower flows can impact water quality, costs, energy consumption, and public health. Currently, there are few tools that can predict physical conditions in low-water flow plumbing that can result in disinfectant loss and biofilm growth.
In response to all this activity, the technical idea is to develop new measurement methods, collect data, and develop models to address efficiency and safety concerns for modern plumbing systems.
What is the research plan? Discussions with individual stakeholders have led us to conclude that experts in water conservation, plumbing design, water quality, and public health desire more engagement with each other. This engagement would inform water use and plumbing guidelines for buildings that would satisfy their respective concerns for building occupants. Additionally, these discussions have highlighted the need for a clear research roadmap for various premise plumbing issues, which does not exist today.
The first product was to host a workshop in FY18 to identify research needs in order to develop a research roadmap. The major output of the workshop will be a document published in FY19 that summarizes the workshop discussion and articulates the measurement science needed to improve the efficiency and quality of water delivered through new and existing premise plumbing systems. Similar efforts for identifying measurement science needs for net-zero energy buildings have proven successful. Subsequent products will disseminate the research roadmap and promote its implementation among key stakeholders in the plumbing industry.
Another product of this project has been to develop and validate methods to evaluate building use water efficiency. In FY18, the team proposed a method for water benchmarking of commercial and residential buildings. In FY19, we will begin an effort to aggregate existing building water use data from around the country to prepare a database. This database will allow for the validation of water performance metrics, and enable more accurate benchmarking of water-efficient plumbing systems. A FY20 product will be a WERB-approved journal publication on the validity of our benchmarking methods and comparing it to new standards, such as the impending RESNET HERSH2O rating.
Plumbing codes cannot be improved without an understanding of how pipe design impacts plumbing system performance. A FY19 focus will be to identify a plumbing flow and temperature model that will predict conditions in pipes of various sizes, materials, and configurations. Data from the model will be helpful for determining conditions such as stagnation or low-flow that are detrimental to aspects of good water quality. Models such as this have direct impact on updating plumbing design and codes; organizations such as IAPMO and ICC have identified the need to update codes for new plumbing systems.
This project will continue the effort to better characterize the connection between water efficiency and water quality in low-flow residential building plumbing systems by publishing data on the Net-Zero Energy Residential Test Facility (NZERTF). The home on our Gaithersburg, MD campus was built with a water efficient PEX-manifold water delivery system and low-flow water use fixtures and appliances. Data taken of sediment concentrations in water heating tanks, concentrations of disinfectant residual and microbiota, and biofilm growth in the plumbing system in FY19 will help characterize the overall performance of the plumbing system. The output, a journal publication, will be written in conjunction with collaborators in FY20.
 U.S. Department of the Interior, U.S. Geological Survey, “Estimated Use of Water in the United States in 2010,”
 U.S. Green Building Council,
 U.S. Geological Survey.
 U.S. Environmental Protection Agency. https://www.epa.gov/research-grants/national-priorities-impacts-water-conservation-water-quality-premise-plumbing-and
 NIST Technical Note 1660. 2010. http://ws680.nist.gov/publication/get_pdf.cfm?pub_id=905024.