dual-flush calc

Hi Henry, If you could provide some more background it might help us answer your question, but it sounds like there are two pieces here: 1. Can you count on a single fixture to reach your target water savings? Unfortunately, typically no, because the calculation is based on the water use of all the fixtures in the building, not just for each type. You need to reach your goal after including all the sinks and showers as well, and if these aren't high-performance, they'll lower the impact of the toilet. It can be difficult to predict which fixtures have the biggest impact on water use reduction. I always use the Indoor Water Use Reduction Calculator available on the USGBC credit library and test out a few scenarios to see what fixtures combinations will work. 2. Can you take credit for lower-than-normal dual flush toilet rates? Yes! The calculator I mentioned above also has a section to calculate the weighted average rate you should use for dual flush toilets, which is based on the default uses per day listed in the Reference Guide.