Water harvesting is no different than renewable energy –
opportunities abound in your building to capture a free resource and turn it into an economical solution. The key is to have the right systems in place.
But what if the only water you could use had to be collected solely from rainstorms and recycled from your restrooms? Would your water habits change if you were responsible for treating all of your sewer excess?
A net-zero water building is an innovative strategy that pushes your building to be fully responsible for generating its potable water needs and treating all discharge waste.
“Net-zero water turns your property into a self-sufficient water resource,” explains Amanda Sturgeon, vice president of the Living Building Challenge. “On the supply side, all of your water must be either harvested on-site or sourced from a closed-loop system. For discharge, no water leaves your project site through city pipes – all waste water is treated and reused or infiltrated within your property. Net-zero water means you’re living within your means of what your site can both provide and clean.”
It sounds like an extreme approach, yet aging infrastructure costs may push more and more responsibility on facility managers to meet their own water demands. The Bullitt Center is one of the first buildings in the U.S. to pursue net-zero water.
While net-zero water is technologically feasible for existing buildings, costs are another matter, as are square footage limitations and code complications. This approach is best suited for new construction, where space can be set aside from the onset for storage tanks, additional piping, and filtration systems.
FMs in existing buildings can nonetheless steer their facilities toward water independence with a host of conservation strategies that capture, process, and recycle this natural resource. Improve your bottom line and your sustainability commitments with these five strategies that reclaim greywater and stormwater.
1) Manage with Meters
Water meters are just as critical as energy meters to understanding your consumption habits. While your main utility meter reports how many total gallons are used, it doesn’t break down loads among occupant, mechanical, and irrigation needs. A typical building may consume equal volumes between these areas, but pool areas, dining facilities, or laundry machines are major variables.
You can expand your submetering to virtually any space or system that consumes water on your property, recommends the EPA. These can include individual tenant spaces, cooling towers, HVAC systems, steam boilers, irrigation, water features, pools, and industrial processes.
“Once you have metering in place, you can understand what your systems are doing at any given moment, trend this data, and make adjustments accordingly,” notes Jeffrey Kling, a mechanical engineer with Gibbens Drake Scott, an MEP design firm.
As with any improvement project, you need to capture a before and after picture. This type of granular usage data will help you determine the feasibility of different systems, model diversion rates, and verify savings.
This information may direct whether you want to focus on a harvesting solution like greywater capture or a conservation measure such as faucet aerators. It may seem like a given to focus on low-flow fixtures, but if your irrigation needs are your largest consumer of water, you could see greater returns by focusing on rainwater harvesting.
Leaks can also represent a huge source of water waste within a building, yet without metering they can be hard to detect, according to WaterSense, a product labeling program offered by the EPA. A sweating toilet may seem like a low priority, but a unit that’s leaking 0.5 gallons per minute could add up to over 21,500 gallons a month. Using an average rate of $8.25 per 1,000 gallons of water, that’s over $2,000 a year for a single malfunctioning toilet.
Any harvesting system should also have meters – it’s imperative to know how much water you can viably collect, treat, and recycle. As with renewable energy, your water “generation” is typically dependent on weather events, seasonal demands, and in the case of greywater, occupant habits.
The same fluctuations also impact when and where you can distribute treated water. Irrigation and cooling demands are likely higher during certain months, whereas flushing volumes probably maintain constant levels. These potential end uses for recycled water will impact your collection and storage methods, as well as dictate filtration requirements. Metering data can help you navigate these nuances.