Building Automation for Management of Water

Editor’s Note: This column appeared in Engineered Systems five years ago, in the March 2016 issue. Enjoy this blast from past, as we resurrect it from our vault.

We almost always think about the BAS as a tool that is a critical part of energy management, so these systems are typically focused on those systems that directly use energy — notably the HVAC and lighting systems. Almost all commercial buildings are also users of water, though; the cost of water and sewer services varies from area to area and can become a significant expense. Worse, in areas where there is a shortage of water, there is not only a big expense but an imperative to conserve.
Conserving water is not all that difficult. It begins with the use of water-efficient fixtures, such as low-flow showerheads, sink aerators, and toilets. Look for other areas of big water usage, such as laundries and dishwashing, to implement more efficient end use. Every gallon of water that can be avoided at end use is a gallon that doesn’t have to be purchased, pumped, or heated. Saving water can save both the cost of the water as well as energy.
The ongoing challenge with water use is that most buildings only meter water where it comes in from the street. Buildings or campuses that pump their own water may not even have that meter in place. Inside the building, there is little tracking of water use. It is fairly easy to install water meters within the building, and these can be as simple as a pulse-style meter that can be integrated into a BAS. There are several key reasons why you should monitor in-building water use from the BAS.

Leak Detection

Water leaks can range from a leaky faucet or toilet to a catastrophic break. By metering water and tracking usage over time, it is fairly easy to detect when there is a minor or major leak. Stopping minor leaks saves energy and water — reducing cost and improving sustainability. Finding major leaks early saves property.

Make-Up Water Tracking

Many HVAC systems are cross-connected to water for makeup. These are common not only on open systems, such as cooling towers, which have a constant need for make-up water to compensate for evaporation losses but also for sealed systems as well. Tracking make-up water in an open system and comparing it against weather data gives a good idea as to the effectiveness of the tower and if it requires service. Large amounts of make-up water into a sealed system are a good indicator of a leak or other system problem.

Sewer Credits

We want to track water usage for any application that does not utilize sewer services. This amount is then eligible for claiming a sewer credit on your bill. Common applications of this are for cooling towers and irrigation. Keep in mind that a BAS can be used as an effective tool not just for energy but for water management as well.