Hi, our project is considering installing metering in our showers as a water saving improvement. But we cannot find any baseline in the LEED-online credit template metering showers.
Does anyone have experience on using metering showers, and in that case how to show compliance on LEED-online. What would the baseline be?
As an option we considered not going for the default values and raising the number of "Total daily uses", and lowering the "Duration" to create the behavior of metering faucets. But our water reduction becomes lower, so this is not beneficial for us.
Thanks!
Seema Pandya
Sustainability ConsultantSLP
150 thumbs up
November 29, 2011 - 4:49 pm
The current default time for showers is 300 seconds (only 5 min). I would imagine that you would have to show your own alternative compliance path for your metered shower fixture. You could use the same logic that is used for metered public lav fixtures and convert the usage to gallons per cycle, ( x gpm * sec cycle)/ 60 sec. The baseline would be what LEED already uses (2.5gpm *300sec)/ 60sec =12.5 gallons per cycle. You then compare it to your design case where you would reduce the cycle, or the gpm. However, the bigger question would be if a metered shower would really even reduce water. The 300 second default is based on behavior patterns. Even if you were to reduce the cycle to 200 seconds, wouldn't someone still need at least 5 min to shower? In reality, they might just set the cycle off again after 200 seconds to finish their shower and then you have someone showering for 400 seconds in reality. If it is the shower head itself that you are reducing, you are better off going with the straight shower calculation anyway with out the metering component.
Veronika Sundberg
Environmental Engineer - CertificationSkanska Sverige AB
120 thumbs up
November 30, 2011 - 3:32 am
Great advise Seema,
We only have cycles of 30 sec (standard) and approximately 5 cycles per person (standard). So if we do the calculations the way you suggested:
(2,1 gpm * 30sec * 5)/60 sec = 5,25 gpc.
(x gpm * 300sec)/60 = 5,25 gpc
X = 1,05 gpm using the default 300 sec value.
The benefit with the metering is that the person taking the shower is not letting the water while shampooing and therefore a shorter time and less water.
Do these calculations seem reasonable?
Thanks, Veronika
Seema Pandya
Sustainability ConsultantSLP
150 thumbs up
November 30, 2011 - 10:16 am
Hi Veronika,
The calculation looks logical. However, how are you deriving that each person will use an average of 5 cycles? Since you are deviating from LEED's prescribed calculation method, the reviewers will no doubt ask for as much back up as possible to support your claim of 5 cycles and why you are not using 300 seconds or 10 cycles to = 300 seconds. If you do decide to go this route, I would also suggest writing a full narrative showing how you used the same calculation logic as the metered public lav. Best, Seema
Veronika Sundberg
Environmental Engineer - CertificationSkanska Sverige AB
120 thumbs up
November 30, 2011 - 10:26 am
Good, we are following our design praxis. But I agree with you that I must find this in written for proper backup documentation. Otherwise they will probably not accept it.
Thanks again Seema for your advices. /Veronika