We are looking to incorporate metered showers into one of our buildings. However, the LEED 2009 WEp1 template does not explain how to consider the use of metered faucets. The baseline calculation assumes a 5-minute duration (300 seconds) with a flow rate of 2.5gpm. The showers we are looking to use last approximately 30-40 seconds with a maximum 1.2 gallons per cycle. The manufacturer recommends 3 cycles per shower (start - first rinse - second rinse), with a total maximum water use of 1.2 x 3 = 3.6 gallons for the entire shower (which last less than 300 seconds).
How should this be taken into account for WEp1 and WEc3? Can we assume that the shower discharges 3.6 gallons total, as opposed to 12.5 gallons total for the base case (2.5 gpm x 5 minutes)?
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77 thumbs up
May 4, 2010 - 6:00 pm
http://www.usgbc.org/ShowFile.aspx?DocumentID=6493
If you follow the link, you'll find a conversion done for faucets, which doesn't seem to make sense, but that's how the USGBC is treating metered faucets vs non-metered faucets at the moment.
However I think you make a good case as well that the baseline is using x-amount of gallons, while your design case is using much less. Also the fact that people use three cycles seems to make sense rather than one cycle
Hannah Pham
20 thumbs up
May 4, 2010 - 8:44 pm
Gustavo,
To be on the safe side, since there is no baseline for metered showers, I would recommend converting gpc to gpm and assume a duration of 5 minutes. However, 1.2 gpc on a 30 second cycle is equivalent to 2.4gpm, whereas 1.2 gpc on a 40 second cycle is equivalent to 1.8gpm (big difference). You'll need to know the actual flow rate. You might be better off to use a non-metered low-flow showerhead. These are a couple options I have come across recently:
http://www.thenaturalabode.com/mm5/merchant.mvc?Screen=PROD&Product_Code...
http://store.wesgogreen.com/omni-shower-head.html
Showerheads are a great way to get water savings. As one of my co-workers pointed out, the owner can always change them out later if he hates the low-flow. By that time, you have no control of (or responsibility for) water usage. Some low-flow shower heads actually feel the same or better than regular ones, though. They have come a long way.
FYI: I am not an authority on LEED so don't take my answer as the final say. I am just making suggestions.
Have fun! ; )
Jean Marais
b.i.g. Bechtold DesignBuilder Expert832 thumbs up
May 5, 2010 - 12:21 am
p171 BD&C userguide Table 2. Default Fixture Uses, by Occupancy Type has Showers as follows
Private Shower @ 2.5 (gpm) at 80 (psi) per shower stall — residential, duration 480 sec
which gives 20 gpc
and
Public Shower @ 2.5 (gpm) at 80 (psi) per shower stall — duration 300 sec
which gives 12.5 gpc
These durations are used to calculate the water volumes used in any event, and although not explicitly a baseline for metering showers, would not be far from the mark. Write usgbc and ask if you could use this as the baseline for metered showers.
Jean Marais
b.i.g. Bechtold DesignBuilder Expert832 thumbs up
May 5, 2010 - 12:24 am
per cycle in context of this credit means per event or usage, meaning that the 3 cycles you used in your example per shower equate to one LEED "usage" cycle.