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)?