COOLING TOWERS. While cooling towers are an effective method of regulating heat gain and cooling within a building, they are rife with inefficiencies—a fact that often goes unaddressed by building operators and engineers alike and, as such, represents an enormous missed opportunity for water savings.
“Cooling towers have a huge amount of water usage,” Arlein says. “Up to 50 percent of the water used [in buildings] is coming from cooling towers, and reducing cooling-tower water usage is not something that’s done very often.”He notes many engineers assume they’re going to use excessive amounts of water in cooling towers and rarely consider ways to find efficiencies. “I think that they need to evaluate cooling-tower water use and find ways to reduce that; maybe that means building owners incentivizing that reduction to engineers.”
Mason says facility managers should also pay attention to the frequency of blow down and consider the amount of drift loss occurring with cooling towers. “Look at the other factors that result in excess water being used and really start to get on top of cooling-tower water management a little bit more,” he says, adding that building owners might want to reach out to contractors that specialize in cooling-tower management to take advantage of this watersaving opportunity.
STORMWATER/RAINWATER. As we move to the exterior of buildings to address water efficiencies, stormwater management, greywater processing and rainwater harvesting are the key strategies to keep in mind, though they vary by region.
“In my opinion, it’s the stormwater side of things as opposed to the efficiency side of things that is driving change—at least in the Southeast,” Ruck says. “You’ve got water coming off these huge structures and all these impervious surfaces, and the regulations are tightening up on how you have to handle that—how much you have to keep onsite.”
In North Carolina, for example, Ruck says building operators should take advantage of the ample precipitation in the region by installing properly designed and engineered rainwater-harvesting systems. Ideally, these systems should incorporate dual-purpose tanks that meet stormwater-mitigation requirements and capture rainwater.
“There are definitely missed opportunities for sure, but if you can take rainwater that once it hits the ground is considered stormwater, which is a liability, and then take that liability and make it an asset then you’re going to get somewhere,” he says, adding that dual-purpose storage tanks are “the future of these systems.”
Mason notes for most existing buildings, creating a rainwater harvesting system without a major renovation of the building could prove difficult in many cases. “We’re sort of hamstrung by the existing infrastructure without doing a major renovation of the facility.”
However, he notes that considerations for capturing rainwater should be reviewed in light of two areas: new systems in existing buildings and retrofitting existing systems. In the latter case, Mason says “with existing systems, the analysis we have conducted indicates the cost of pumping the water is greater than the cost of water, thus it does not currently make economic sense.”