Forum discussion
CI-2009 WEp1: Water Use Reduction—20% Reduction
USGBC "Water Use Reduction Additional Guidance" dated Dec. 1, 2009 and updated Aug. 16, 2020 has table 1 which states the baseline default for lavatory with autocontrol at 12 second cycle which calculates to 0.1 GPC at 0.5 gpm (12/60 * 0.5).
The online template for flow fixtures inputs a baseline of 0.25 GPC for metering lavatories. Is this correct?
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Karen Blust
Green Building ConsultantThe Cadmus Group
124 thumbs up
November 15, 2010 - 5:02 pm
As per the guidance in the Water Use Reduction Additional Guidance document dated December 1, 2009 and updated August 16, 2010, “When using a metering (or autocontrol) faucet, please select the Metering Lavatory fixture in the Fixture Type pull-down menu of the Flow Fixture Data table. The Baseline case flow rate for a metering faucet is .25 gallons per cycle (gpc). Since the flow rate is measured in gallons per cycle, the duration is not necessary. Therefore the Duration can be disregarded and should not be modified for the metering lavatory fixture type. The “Installed” flow rate must also be entered in gallons per cycle. If the flow rate in gallons per cycle is not known, the value must be determined through a separate conversion calculation and then entered into the table. The flow rate is determined using the flow rate in gallons per minute (gpm) and the duration setting (in seconds) for the metering faucet. The typical duration setting for the installed metering faucet is 12 seconds, however a different duration may be used if supported by manufacturer’s specifications.” To sum, the baseline case flow rate for a metering faucet is 0.25 gallons per cycle (gpc). The design case flow rate should also be entered into the LEED Credit Form in gpc. However, if gpc is unknown for the design case, the project team may calculate the gpc by multiplying the flow rate times the duration, and divide that number by 60 seconds.
Carl Sherman
CPD, LEED A.P.Weigand Associates
27 thumbs up
November 15, 2010 - 6:39 pm
The guidance refers to metering and "autocontrol" faucets. I checked the faucet I am using today; The Sloan Solis is an "on demand" faucet, so it runs when you put your hands in the sensor path, and shuts off when you remove your hands. Another faucet I use, the American Standard Selectronic has an adjustment from 3 to 240 seconds. If the faucet is on demand or adjustable, how can you document the cycle time? Perhaps using 12 seconds for the average is a safe guess? With a flow control at 0.5 gpm and 12 second cycle time, the cycle usage is 0.1 gallons per cycle which can result in considerable savings over the 0.25 gpc baseline.
Lorey Flick
PartnerFlick Engineering Professionals
38 thumbs up
August 31, 2011 - 12:02 pm
Carl, did you ever receive any guidance on the assumption of using 12seconds as the average for the "on demand" lav's? Please advise
Rubén M. R.
CodirectorCIVITA
106 thumbs up
October 11, 2011 - 1:42 pm
Carl and/or Lorey,
I have the same question about the assumption of 12 seconds average for the "on demand" faucets. Please let me know if you've got any info.
Thanks!
Nancy Henderson
Managing MemberArchEcology, LLC
83 thumbs up
May 10, 2012 - 5:55 pm
Does anyone have new information about this? We have recently been made aware that our auto-sensor faucets come from the factory with a 30 second preset. This means if you hold your hands under the faucet continually, the faucet will shut off after 30 seconds. If you remove your hands the faucet shuts off. We have interpreted this as a 30 second cycle. The faucets can be reset in the field to 13.75 seconds, which we are doing so we can use a 13.75 second cycle time. Are we interpretting this correctly?