When calculating for a low-flow fixture, it is required to enter a duration (which is default set to 30 seconds). There is a footnote that says "Duration may be modified for special circumstances". I have no idea what this means. It makes sense that a metered faucet would have a duration, but a low-flow fixture just runs for as long as needed (probably like 12-15 seconds each use). When I calculate total water reduction with low-flow fixture duration set to 30 seconds, I do not hit the 20% reduction needed for the prerequisite. But when I change the duration to 15 seconds, I can hit the 20%. Is it ok for me to change the duration?
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Carlie Bullock-Jones
PrincipalEcoworks Studio
LEEDuser Expert
220 thumbs up
September 23, 2012 - 11:27 am
Hi Kevin,
The lavatory duration should be listed in the form calculations as a 30 second duration, as outlined in the LEED Reference Guide for Green Building Design and Construction, 2009 Edition (Updated June 2010) Addenda (WEp1 posted 2/2/2011).
If you have a metering type / autocontrol lavatory faucet, the duration may be set to as low as 12 seconds; in this case you will have to convert from GMP to GPC as outlined in the Water Use Additional Guidance document on the USGBC website (http://www.usgbc.org/ShowFile.aspx?DocumentID=6493).
Hope helpful!
Kevin Short
September 24, 2012 - 11:56 am
Carlie- Thanks for the response. I am still unclear why 30 seconds is the duration... this seems like a long time for water to be running. Regardless, I know I can set the duration to 12 seconds with a metering type faucet, but I am unclear as to what you mean by an autocontrol faucet? Can this be just any type of hand sensor activated faucet, or does it have to be one of the types that runs for a specific period of time once activated? Thanks again for the help.
Carlie Bullock-Jones
PrincipalEcoworks Studio
LEEDuser Expert
220 thumbs up
September 24, 2012 - 6:51 pm
Kevin - this would include either an autocontrol faucet with metering control (dispense water for a pre-determined period of time) or automatic fixture sensor (motion detector).