The Smart Grid for Water

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Energy is rightfully top of mind for building professionals, and it should be with its cost and environmental impact. Looking at buildings specifically, which consume about 40% of primary global energy this is natural and obvious focal point. Less obvious is the link that water has to energy, but it is there nonetheless. High performance buildings aim to do more with less and are designed to be resource efficient buildings. Many high performance buildings are integrating water consumption measures in the design and retrofit stages. Low flow aerators, pint-per-flush (or waterless) urinals, rain-water harvesting, and on-site wastewater treatment are occurring more and more frequently. These savings efforts can be equated to energy-saving technologies like LED lights, variable frequency drives, and other proven energy efficiencies.

Like energy savings opportunities, measurement is required to verify and track savings efforts. These savings are more difficult to quantify, as water, particularly in Canada, is undervalued and still very inexpensive. This will change: the EPA anticipates that 36 states will see water shortages by 2013, even under non-drought conditions. Aging infrastructure will need to be replaced by municipalities, and someone will bear that burden, and it will be consumers of the service. A recent report from the Building Owners and Managers Association (BOMA) in Canada showed an average annual water consumption of about 49 gallons/ft2 for commercial buildings. Canadians are the 2^nd worst per capita consumers of water, surpassed only by Americans.

The bright side of this gloomy story is that efficiency paths are as well defined as in the energy sector. The Earth Rangers Centre (ERC) had many of these features adopted in the design phase including rainwater harvesting, a dedicated wastewater treatment plant, potable water from an on-site well, and drought hardy landscaping that required irrigation only for establishment. These efforts attained all five credits under LEED for New Construction, contributing to the Gold status attained. All treated wastewater is stored in a 80,000 gallon holding tank, which is used to flush toilets and urinals, water the green roof (when required), for animal area cleaning (a process use unique to the Earth Rangers Centre), and as a source for fire suppression, should the need arise.

Retrofits of low-flow aerators, additional water meters, low-flow shower heads, and reduced flow urinals and toilets were retrofitted over the last couple of years. These efforts have decreased the impact on the local water table by 67%. To compare to the BOMA report, the ERC pulled only 3 gallons/ft2 from the local water table. The remaining consumption needs (6 gallons/ft2) were met through effluent reuse and rainwater capture. That is an 80% reduction from national averages-enough to target every water-related credit under LEED for Existing Buildings, Operations and Maintenance. As a result, the local municipality did not have to run a sewer main to the building, nor a city water line. All of these systems come with a cost, but are being adopted in greater frequency as current infrastructure hits design thresholds. The savings are attainable, as the ERC has proven. The entire system is the equivalent of the smart grid, but for water, instead of energy. It has the equivalent of on-site generation (wells and rainwater capture), real-time metering, and distributed infrastructure.

The water cycle in building of integrated design can and should be more complex, but is necessary to minimize consumption and truly make high performance buildings resource efficient, not only energy efficient. Like energy management, water management requires measurement and timely data for users to understand real impacts, and the need to conserve this precious resource is growing. The good thing is that the tools to manage this resource are already available, and conservation measures are well-established.