Updated Water Certification Matrix Tool Spotlights Water Efficiency Programs

This post has been updated.

NAHB’s Sustainability & Green Building team has updated its Matrix of Water Efficiency Rating Systems to reflect developments over the past few years and provide more detail on water use planning. The matrix provides information on applicability, requirements, costs and scope for these certification programs.

The new water matrix includes the addition of the Water Allocation Planning Tool. The update also depicts in more detail how the water rating index (WRI) can be pursued independently from ICC 700-National Green Building Standard® (NGBS) Green certification, if desired. Another change is the inclusion of the EPA’s WaterSense Version 2, which has replaced Version 1.

The new Water Allocation Planning Tool is intended for planners directed to suggest programs for adoption by jurisdictions facing water restrictions. This addition makes the matrix more relevant for these planners trying to decide what to do with diminishing water supplies in the face of growth in their markets. This addition also could benefit builders or home buyers looking for certification if they are conscientious of their water use.

Certifying your project to an above-code, voluntary water efficiency rating system provides independent confirmation of the water-saving practices you have installed in your projects and validates to your buyer and the local market that you have built a house to a higher standard than what code requires.

The matrix provides information on several programs:

• NGBS: NGBS has long recognized and rewarded builders’ efforts to implement water conservation and efficiency practices.
• WRI through NGBS: The 2020 NGBS introduced the WRI as a new optional path for newly-constructed homes to demonstrate compliance with water efficiency criteria.
• WERS: The Water Efficiency Rating Score (WERS) originated in the Southwest, where water scarcity threatens to limit residential building in some jurisdictions. Outdoor water use is generally a higher percentage of overall use in this region. Efficient outdoor use and water reuse are recognized in the program along with indoor use.
• HERSH2O: RESNET HERSH2O is a water efficiency program that complements its HERS Index Score for energy efficiency and provides a relative efficiency of the home as compared to a baseline.
• WaterSense: EPA’s WaterSense program provides a voluntary path for home certification using certified high-efficiency products.

This matrix tool allows you to quickly evaluate and compare the features and requirements of several above-code water efficiency and conservation programs to assist in your decision-making. It also allows you to choose what tool works best for you and your intended goals.

The matrix is one of many NAHB Green Resources available to builders and developers. Check out more at nahb.org/green, including the Builders Toolkit for Water.