the hansgrohe thermostatic valve I recently got does allow both outlets to be used at the same time (turn the small lever to lower than full left or full right).

don't know anything about the calgreen requirements myself tho

hi lee, do you have the model #? which state are you in>

M_N_A, according to our "green consultant" you are allowed to have multiple showerheads, but flow rates are governed by the standards. (Our project is required to be green point rated)

We will have some baths with both an overhead shower and a handshower. In those instances both fixtures will not work at the same time.

We also are going the 20% route because we have a couple of tub handshowers with 2.5gpm flow rates. My understanding is that if you have enough fixtures with low flow rates to get to an overall 20% reduction from baseline use, then you're still ok. Apparently it is a bit complicated to calculate, the consultant is doing it for us.

Good luck!

thanks Oaktown. can you please explain the 20% route?

I find all these rules are so frustrating and ridiculous. are they gonna regulate how long I am taking my shower too?

M_N_A,

I'd suggest you contact Build It Green or someone who could tell you for certain.

My understanding is that Calgreen 2012 allows you to comply under a prescriptive method (each fixture has a max flow rate) or a performance method (total combined use still shows a 20% or more reduction from baseline water use).

I *think* the multiple showerheads language means that one of the following needs to happen: (1) all of the heads together have to have a flow rate of 2.0 gpm or less, OR (2) each one needs to be 2.0 gpm or less and you can only use one at a time, OR (3) you follow the performance method and then each can only be max 2.5 gpm. (Someone please correct me if this is wrong!)

Because we had two handshowers with flow rates above the prescriptive amount, we had to use the performance method.

This is what our consultant did:

First, calculated our "baseline" usage using form WS-1 in the link below.
Second, calculated our proposed usage using form WS-2 in the link below.
If the "proposed use" number in WS-2 shows a reduction of 20% or greater from the number in WS-1, you're good.

I don't know why the WS-2 includes kitchen faucets when the code says the reduction measurement is limited to "showerheads, lavatory faucets, water closets and urinals." Our consultant only calculated with the showerheads, lavatory faucets, water closets.

I suspect if I tried to do the calculation myself it would be more frustrating than taxes . . . Good luck.

Here is a link that might be useful: Links to baseline and 20% reduction water usage

This post was edited by Oaktown on Thu, Sep 26, 13 at 21:02

Welcome to California... Sigh...

Oaktown, thank you so much for your detailed explanation!