Indoor water use reduction

Intent

To reduce indoor water consumption.

Requirements

Option 1. Calculated Water Use

Establishment

For the indoor plumbing fixtures and fittings listed in Table 1, reduce water consumption to or below the LEED v4 for Existing Buildings: Operations & Maintenance baseline, calculated assuming 100% of the building’s indoor plumbing fixtures and fittings meet the flush and flow rates listed in Table 1.

The LEED v4 for Existing Buildings: Operations & Maintenance water use baseline is set depending on the year of building’s occupancy, as follows:

• For a building with a certificate of occupancy dated 1995 or later, the baseline is 120% of the water use that would result if all fixtures met the code requirements in Table 1.
• For a building with a certificate of occupancy dated before 1995, the baseline is 150% of the water use that would result if all fixtures met the code requirements in Table 1.

Table 1. Fixture and fitting code requirements

If indoor plumbing systems were renovated after initial occupancy of the building, set a whole-building average baseline by prorating the above limits, based on the proportion of plumbing fixtures installed during the plumbing renovations in each period. Pre-1995 buildings that have had only minor fixture retrofits (e.g., aerators, showerheads, flushing valves) but no plumbing renovations in or after 1995 may use the 150% baseline for the whole building.

Calculate fixture and fitting performance to compare the water use of the as-installed fixtures and fittings with the use of Uniform Plumbing Code or International Plumbing Code-compliant (baseline) fixtures and fittings.

Inspect all existing fittings or fixtures to ensure they are operating properly. Make any repairs needed to bring all fixtures into good working order or permanently turn off water supply to nonfunctional units.

Implement a fixture and fitting replacement and retrofit policy specifying that all newly installed toilets, urinals, private lavatory faucets, and showerheads that are eligible for labeling be WaterSense labeled (or a local equivalent for projects outside the United States).

Performance

For building water use, confirm that calculations are up to date. Demonstrate that all applicable purchases made during the performance period meet the requirements of the fixture and fitting replacement and retrofit policy.

Option 2. Metered water use

Establishment

Meter fixtures and fittings and record metered data for one year to establish a water-use baseline.

Performance

For projects with at least 80% of fixtures and fittings metered, show that the water-use baseline has been maintained.

Behind the intent

The use of potable water in buildings constitutes a large portion of freshwater consumption. Strategies to reduce potable water use in buildings will entail the selection of plumbing fittings, fixtures, and equipment that use less water than conventional standards. Fixtures are now widely available at 20-50% below code required levels. The WaterSense label was developed by the U.S. Environmental Protection Agency to identify these efficient fixtures and to ensure that the higher efficiency does not come at the cost of user satisfaction or performance. The WaterSense label has been incorporated as a requirement for this credit in order to ensure that fixtures in a LEED building are water efficient and high performing.
In buildings with water heavy processes, appliance and process water use can sometimes exceed water use from fixtures and landscape combined. This is especially true for buildings with cooling towers or evaporative condensers, which have the potential to be major water users. Process water use is therefore addressed specifically with a separate set of requirements.
Because the WE section is designed around an ‘efficiency first’ model, the prerequisite deals only with the efficiency of fixtures and fittings, while alternative or nonpotable water sources which offset potable water demand are also addressed in the corresponding credit.

Step by step guidance

Common steps

The calculation to support this prerequisite compares a design case to a baseline case.

1. Be certain to select WaterSense Fittings and Fixtures for those units that are subject to WaterSense labeling.
2. The calculation for this prerequisite is:

Changes from previous versions

The year for the baseline multiplier cutoff has changed from 1994 to 1995
The multiplier for projects built and occupied before 1995 has changed from 160% to 150% of UPC/IPC.
Duration based savings for autocontrol faucets with automatic fixtures sensors or metering controls are no longer allowed in the design case. Studies have shown that autocontrol faucets do not result in savings as users frequently reactivate the faucet after initial use or stop washing before the cycle ends.
Applying non-potable water will no longer be allowed as an Alternative Compliance Path in the prerequisite. Alternative water source can earn points in the corresponding credit.