Indoor Water Use is the measurement of potable water use for indoor plumbing fittings, fixtures, and equipment. The in-app water tool uses a usage-based methodology that calculates full-time-equivalent (FTE) and transient occupants’ estimated use per day and applies appropriate fixture use rates to each. The calculator estimates the percentage reduction of potable water use, compared with the baseline, using the following equation (from LEED v4 BD+C Reference Guide; WE p2: Indoor Water Use Reduction - Equation 1).
The water fixtures are calculated by taking into account the occupant density input from the baseline page, the FTE and Visitors for your building type. For this, cove.tool uses the table below to calculate uses per day and duration. (From LEED v4 BD+C Reference Guide; WE p2: Indoor Water Use Reduction - Table 8)
Why not use the fixture-count calculation method?
In traditional plumbing design, water usage (gal/yr) is based on fixture counts; this methodology effectively estimates design case water-use but does not prioritize water-use reduction strategies. Potable water usage in buildings constitutes a large portion of freshwater consumption, so just calculating code-required levels of water fixtures and portable water use is not enough. A secondary method, known as the usage-based calculation, has teams calculate the percent difference in efficiency between a baseline case model and the design case. This “efficiency first” methodology stresses the selection of efficient plumbing fittings, fixtures, and equipment.
Where do I input the number of fixtures?
Currently, the platform only has an input for uses per day, but this input can be edited to reflect your corresponding values by taking into consideration all the water fixtures in your project.