May 2017

An Introduction to the Water Efficiency Rating Score (WERS®)


Mike Collignon


The use of analytics, modeling and metrics is increasing, whether it’s in advertising, sports or social media. Now it’s making its way into the construction industry. In the energy-efficiency world, there is the Home Energy Rating System (HERS) and the Department of Energy’s Home Energy Score (HES). Water efficiency now has a performance-based metric: The Water Efficiency Rating Score, or WERS®.


What is WERS®?

WERS® is a predictive, performance-based approach to residential water-efficiency and water-resource management. WERS® is the culmination of calculations that consider the loading from principal plumbing fixtures, clothes washers, structural waste and outdoor water management. Potential rainwater, greywater, stormwater and blackwater catchment are also calculated. The WERS® Program is applicable for both new and existing single-family and multifamily residential properties. It uses a scoring scale of zero to 100, with zero being the most desirable and 100 representing the baseline home. In addition to the score, the property owner also receives a daily, monthly and yearly projection of water usage and, if water rates are entered, a cost projection over those same time intervals.


Project teams will have the ability to use the WERS® Design Tool to view initial estimates of the results of their proposed installed fixtures and appliances, as well as innovative water conservation strategies, without the involvement of a WERS® Verifier. In order to obtain a WERS® certification, the project team will need to enlist the services of a qualified third-party WERS® Verifier, who will then check that fixtures, appliances and strategies have been installed or implemented as claimed. Once the project has been verified, documentation is sent to the Green Builder® Coalition for certification processing. The certification document that is issued could then be utilized by the project team for anything from compliance with a water-conservation tax credit or incentive to a local building code that requires third-party verification.


How is WERS® being used?

Unlike a prescriptive program, a performance-based program gives all parties (architect/designer, builder, property owner) design and product flexibility. It doesn’t require anything. Rather, it assesses the choices made. The same flexibility extends to the implementation of the WERS® Program.


On its own, the WERS® Program can help a property owner understand where and how water is being used. Without this knowledge, it’s difficult to determine the most cost-effective conservation strategies. For those who utilize wells, the combination of the projections and the deeper insight into their system’s capabilities can help manage overall water usage. This can prove very helpful when faced with extended dry spells.


A voluntary modeling tool is just one way to use the WERS® Program. It can be adopted as a regulation. In October 2016, the City of Santa Fe became the first municipality in the nation to integrate a performance-based water-efficiency requirement in its residential green building code. The County of Santa Fe is taking a long look at the WERS® Program to determine how it might want to implement this innovative new approach to water efficiency.


The State of New Mexico allows a builder or new property owner to attach a WERS® report to show compliance with the new water-efficiency requirement of the state’s very popular Sustainable Building Tax Credit. The WERS® Program joins Build Green New Mexico and LEED (Leadership in Energy and Environmental Design) for Homes as compliance paths for water.


The GreenHome Institute (GHI), after months of discussion, scrutiny and testing, has started the process of implementing the WERS® Program as the water criteria for GreenStar, its residential green building program available nationwide. Projects that achieve predetermined WERS® will obtain a majority of their water points for various certification levels. “Home energy scores and models are now becoming the norm, said Brett Little, executive director of GHI. “Why not water next? It just makes sense. You can’t manage what you don’t measure, and you easily weed out most waste through informed design.”


Growing Support

In addition to the entities mentioned above, the WERS® Program has received promotional support from both the National Ground Water Association (NGWA) and the American Rainwater Catchment Systems Association (ARCSA). Meanwhile, the WERS® — Manufacturer program currently has two members, Evolve Technologies and EcoVie Environmental, LLC. Both manufacturers are offering discounts on specific products deployed on projects pursuing WERS® certification. By the end of 2017, the number of manufacturers is expected to double.


From the start of 2015 through March 2017, the WERS® Program will have been a part of 22 educational sessions at national or regional conferences.


Mike Collignon is the executive director and co-founder of the Green Builder® Coalition. He is also chair of the WERS® Development Group. He can be reached at




Print Friendly, PDF & Email

Related Articles