Throughout the world, and certainly, in the United States, communities are facing significant water-related challenges. The United Nations projects that global water demand will outstrip the supply by 40 percent by 2030. Shocking news reports about cities like Chennai, India and Cape Town South Africa running out of potable water capture our attention, as US cities face similar risks: El Paso, San Antonio, Houston, Salt Lake City, Atlanta, Los Angeles, San Francisco, and Miami are all facing the real issue of water scarcity.
Water, climate change, and the real estate industry are inextricably linked. Climate change is causing weather patterns to shift, exacerbating drought in some areas and increasing rainfall in others. And when drought is an issue, the energy required to deliver water exacerbates our energy and carbon challenges. We have published an ebook with climate resilience strategies including drought. There are also design strategies to help mitigate the issue of water scarcity and drought.
If you are designing or building in a city that faces water scarcity, you may want to consider a Net Zero Water approach. Like Net Zero Energy, Net Zero Water is intended to help a building achieve self-sufficiency from the water grid.
What is Net Zero Water? How is it defined?
Net Zero Water is achieved when the unused water matches the natural hydrology of the site. In most cases this can be measured through a simple formula: (within the site boundary), Rainwater = water used + infiltrated. In other words, 100% of rainwater and wastewater must be treated and managed either through reuse, a closed loop system, or infiltration on site.
“Project water use and release must work in harmony with the natural water flows of the site and its surroundings. One hundred percent of the project’s water needs must be supplied by captured precipitation or other natural closed-loop water systems,14 and/or by recycling used project water. All stormwater and water discharge, including grey and black water, must be treated onsite and managed either through reuse, a closed loop system, or infiltration. Excess stormwater can be released onto adjacent sites under certain conditions.”
The bold for emphasis is ours. The goal with Net Zero Water is essentially to allow a building site to plug into the natural ecology and water cycle as if the building wasn’t there – eliminating the strain of conventional stormwater and wastewater management on municipal and natural systems. A Net Zero Water building is designed to minimize total water consumption, maximize alternative water sources, and minimize wastewater discharge from the building.
What states/municipalities are incentivizing Net Zero Water?
As issues with water scarcity, quality, and infrastructure continue to grow, sustainable water use programs, policies, and regulations are beginning to emerge as priorities at the city-level.
The City of Seattle is a leader in this space. Seattle drinking water is sourced from two rivers that originate in the central Cascade mountains. Because of Seattle Pacific Utilities’ aggressive water conservation efforts, demand for potable water has declined even as Seattle’s population has expanded. This can be attributed in large part to the City’s green building requirements and practices.
The City of Tulsa is working on a proposed ordinance for Net Zero Water projects that would allow homes to collect and treat their own water and be off the city water and sewer system. It remains to be seen if these single-family home and duplex ordinances will eventually develop into regulations for larger-scale commercial projects.
The City of Alexandria in Virginia is not requiring or incentivizing Net Zero Water at this time, but the issue of water performance is core to their building code requirements, with an expected reduction in water use of 29% compared to developments abiding by the city’s previous standards established in 20019.
Why should developers, architects, and owners be thinking about Net Zero Water? What is the business case for NZW?
Microsoft sets an example. In a 2017 blog post, they explain that Microsoft has a comprehensive water strategy that includes understanding water-related risks and business impacts in the places where they operate; setting goals and improving water use; and advancing innovative solutions to water challenges. This understanding of water’s impact on their business motivated the company to pursue and achieve a Net Zero Water certification for their Silicon Valley campus.
What technologies/strategies help a project achieve Net Zero Water?
The captured precipitation can include rooftop harvested precipitation, groundwater, surface water, stormwater, and/or on-site reclaimed water sources.
As with any sustainability strategy, it’s important to state the Net Zero Water goal at the onset of the project and build the goal into early design strategies and reviews. Include language in contracts that include performance metrics on water use, including a provision to meter or submeter the building’s water use, major water-consuming equipment, alternative water systems, and on-site wastewater treatment systems.
What certifications are available to backcheck NZW?
LEED: The USGBC offers the LEED Zero certification for energy, water, and waste. A Net Zero Water certification recognizes buildings that achieve a potable water use balance of zero over 12 months. The LEED Zero certification for water is performance-based and is achieved through a GBCI review of 12-months of performance data.
Living Building Challenge: Living Building Challenge has a Net Zero Water certification. LBC is recognized as one of the most vigorous back-checks on Net Zero Water, which ILFI defines as having 100% of the building’s water use come from captured precipitation or closed loop water systems that account for downstream ecosystem impact and that are appropriately purified without the use of chemicals.
The bottom line is that water is a critical component of a building’s design and operations. And every building exists in the context of its community. If you are building or operating real estate in a region that is facing drought, your project should include strategies to better manage water.
- PAE Living Building Approved in Portland
- Microsoft Net Zero Water in Silicon Valley
- The University of Pittsburgh Center for Sustainable Landscapes at Phipps Conservatory and Botanical Gardens
- ReNEWW House
- Finding your water balance yields huge savings
- Regulatory Pathways to Net Zero Water
- Free download: Net Zero Energy: Why and how to pursue Net Zero Energy for your new and existing buildings