Hi folks,
This prerequisite says that the baseline water flow for lavotory and showerheads should be measured at 60psi and 80psi respectively. However, this pressure is far to high for a ground floor building, which is the case of our project. In Brazil water pressure is measured in MCA (meters of water column). 60psi is equivalent to 40mca, and 40mca means the situation for a 10 floor building. Definitely not our case. We have a single floor building, so the correct water pressure to adopt for water calculations is 4mca (one floor is approximately 4 meters high). Adopting 40mca/60psi as the water pressure will critically jeopardize the real water savings we are having. So we are thinking of just considering the flow rate at 4mca in the LEED online template.
Anyone with a similar problem? Do you think this is a situation we can justify?
Thanks!
David Sheridan
LEED SpecialistUSGBC
18 thumbs up
August 27, 2012 - 12:42 pm
The 60 and 80 psi references relate to the testing protocol for flow fixtures. Faucets and showerheads are tested at these pressures to confirm that they meet the applicable flow rate limits. These reference pressures should not be construed as requirements for water pressure in project buildings.
LEED Interpretation 829 describes a project-specific testing approach that you might consider if you want to incorporate lower flows at lower pressure into your WEp1 / WEc3 calculations. Note that you would need to test baseline and design fittings and fixtures at the reduced pressure. You may not compare design fittings and fixtures at lower pressure to baseline fittings and fixtures at the stipulated higher pressure.
I would guess that you will end up at about the same place, after doing a lot of testing.