Consulting-Specifying Engineer - June 2008 - (Page 16)

M/E Roundtable Not a drop to waste Engineers debate the various methods of saving water, including sensoractivated faucets, no-flush urinals, and gray water recycling. BY MELISSA HILLEBRAND, Associate Editor CSE: Do sensor-activated faucets really save water? J. PATRICK BANSE: Sensor faucets are more sanitary than handle-type faucets, and with preprogrammed “on” times, reduce the water use and possibility of leaving the faucet running longer than needed. Flow-control devices are the real water savers, as they limit the flow rate discharge of water to the user, which also minimizes splashing and saves overall water use. SHAWN MARTIN: Yes, in most cases. Many users leave water running while brushing teeth, shaving, and the like. Metered or sensor-operated faucets eliminate that waste. They also guard against situations where the water is accidently left running after the user departs. They have the added benefit of providing improved usability for individuals with disabilities. ROB ZIMMERMAN: We don’t know that sensor faucets save water. While the arguments others [like Martin, above] make are true, they are offset to an unknown extent by a higher usage rate. In other words, a higher percentage of people wash their hands in public restrooms if they don’t have to touch the faucet. Some small studies suggest this more than offsets the water efficiency, but more work needs to be done. CSE: What can existing commercial buildings do to cut back on water consumption when there are urban water problems? MARTIN: There are several options. Conduct a water inventory to determine the flow rate of plumbing fixture fittings—any using more than EPAct 92 levels should be upgraded immediately; look for and repair any water leaks (faucets, toilet flappers, etc.); upgrade gravity flush water closets to WaterSense devices; install dual-flush commercial water closet flush valves; replace urinals with no-water or pint-flush models; check the aerators on faucets; consider changing faucets to metered or sensor-operated models; consult a plumber and see if a demand-driven recirculation system can be retrofitted to your system—they eliminate water dumped down the drain while waiting for hot water; replace commercial kitchen pre-rinse spray valves with low-flow models; and consider reducing the water pressure of your plumbing system. ZIMMERMAN: [Responding to Martin] We [Kohler] also don’t know whether dual-flush flushometers really save water. It’s assumed that people use the short flush twice as often as the long flush, but that is based on residential studies of informed users. I haven’t seen any field studies that show what the relative frequency of short to long flushes is in public settings. CSE: Are there HVAC approaches to saving water? BANSE: Collecting cooling coil condensate from air handlers and using it for cooling tower makeup is a good method. Make sure cooling tower blow-down meters are calibrated correctly and makeup water valves close off completely. Check that chilled and heating water systems remain as closed systems and are not leaking. Shutting down cooling systems during unoccupied times also is an option that limits or eliminates cooling tower evaporation and discharges to drain as long as there are no critical areas to keep in (Continued on page 19) PARTICIPANTS J. Patrick Banse Senior Mechanical Engineer Smith Seckman Reid Inc. Houston Shawn Martin Technical Director Plumbing Manufacturers Institute Rolling Meadows, Ill. Rob Zimmerman Senior Staff Engineer—Water Conservation Initiatives Kohler Co. Kohler, Wis. 16 Consulting-Specifying Engineer • JUNE 2008

Table of Contents Feed for the Digital Edition of Consulting-Specifying Engineer - June 2008

Consulting-Specifying Engineer - June 2008 Contents Viewpoint Letters News M/E Roundtable No Gambling Allowed on Smoke Control in Las Vegas Be Prepared: Hospital Protections for Catastrophic Events Ready for Retail Commissioning Documents: Necessary Evil Codes & Standards Codes & Standards Case Study Equipment Lifecycles New Products Advertiser Index Green Space

Consulting-Specifying Engineer - June 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.