Pressure of water supply for faucets/showerheads

Fascinating question Shilpi. I think that ultimately the intent of the USGBC is to measure the amount of water your fixture uses relative to a standard fixture. If an IPC-compliant faucet uses 0.5 gallons for a 15-second handwash, the bottom line is how much water your faucet uses for the same wash. If the reality of your building is that you operate the building with low water pressure (intentionally and permanently) and therefore use X gallons of water for that handwash, you should accurately depict your building in the template and explain your situation in detail. I think it makes sense, but, as always when you're working outside the box, the burden of proof will be on you to make a convincing argument.

Yes, you should use your actual GPM rate based on your PSI. In other words, how much water do you actually use? That is the basis of the credit.

I'm not so sure this is correct. At a specific pressure, a specific flow will issue from the fixture. If the intent is a percentage improvement against a baseline fixture, and the baseline flowrates are specified at a set pressure, then you'll need to supply the flowrate of your design fixtures at also the same pressure as the baseline. Otherwise you could argue that installing a baseline fixture in your facility will cause a smaller water consumption than your design fixure choice.

It's an interesting point Jean. I guess it comes down to determining if an alternative way to achieve the intent of this credit is to focus on water pressure rather than fixture flow/flush rates. Either one has the ability to reduce water use per flow/flush, which is the ultimate intent of the credit. That being said, its an entirely different compliance path than is imagined by EBOM, so one would have to be keenly aware that GBCI may choose not to approve it for a variety of reasons. As is often the case, there's the tried-and-true route, and then there's alternatives that require a careful balancing of risk/reward before they're embarked upon. . .

You will need to upload manufacturer data verifying the flow rate and pressure if it's different from the UPC/IPC values, and a good reviewer should notice that the testing associated with that value is not at the standard PSI. I agree with Dan that if you aren't able to report flow at the specified PSI, you should expect to either pre-vet your strategy through a CRI or be prepared for clarifications during the review process.