6.6 Metering, Submetering, and Cross-Category Water Strategy

Measurement Turns Use Into Manageable Information

You cannot manage what you cannot measure, which is why LEED makes Building-Level Water Metering a prerequisite in BD+C. The prerequisite requires installing permanent water meters that measure total potable water use for the building and associated grounds, and committing to share whole-project water data with USGBC for at least five years (or until the building changes ownership). The data feeds USGBC research and verifies that designed savings actually happen in operation.

Metering vs. Submetering

• A whole-building meter reports one total consumption figure - useful for tracking trend and verifying the 5-year reporting commitment.
• A submeter isolates a specific subsystem so the team can see where water goes.

The optional Water Metering credit awards a point for installing permanent submeters on two or more of the following subsystems: irrigation, indoor plumbing fixtures, domestic hot water, reclaimed water, boiler/cooling tower makeup, or other process water. Submetering converts a single mystery number into actionable detail.

Worked Scenario

A building's whole-building meter shows water use 30% above the model, but the operator cannot tell why. Adding submeters to irrigation, the cooling tower, and indoor plumbing reveals that the cooling tower is running at low cycles of concentration and bleeding excess blowdown. The submeter did not fix anything, but it directed the team to the right lever - a process-water correction - which then delivered the savings. This is the canonical metering-then-act pattern the exam tests.

Cross-Category Connections

Water Efficiency rarely stands alone, and LEED's integrative-process philosophy expects you to see the links:

• Sustainable Sites: rainwater management for runoff overlaps with rainwater harvesting for nonpotable supply - same captured water, two category goals.
• Energy and Atmosphere: cooling towers and domestic hot water consume both water and energy; reducing hot-water use saves heating energy too.
• Operations and Maintenance (O+M): ongoing metering, leak response, and recommissioning keep certified savings real over the building's life.
• Materials and Indoor Environmental Quality: low-flow fixtures and reclaimed-water signage intersect with occupant experience.

A Final Exam Sequence

Resolve WE questions with identify, reduce, substitute, meter, correct: identify the end use (indoor/outdoor/process), reduce demand with efficient fixtures or planting, substitute nonpotable water where quality fits, meter to make use visible, and correct leaks or abnormal patterns. Not every item uses every step, but the sequence finds the best answer. Remember that the answer must address the specific lever the stem names - a meter is the answer to a diagnosis question, never to a demand-reduction question.

Why USGBC Collects the Data

The five-year data-sharing commitment is not bureaucratic box-checking. Historically, modeled savings and actual operational performance diverge - the performance gap. By aggregating real metered consumption from thousands of certified buildings, USGBC can calibrate future rating systems, identify which strategies deliver in practice, and feed building-performance research. For the exam, associate building-level metering with both operational accountability (the owner can verify savings) and industry learning (USGBC improves LEED from real data).

Metering in the O+M Rating Systems

Metering takes on even more weight in LEED for Operations and Maintenance (O+M), the rating system for existing buildings. There, ongoing water tracking, performance benchmarking, and recommissioning are central, because an O+M project is certified on how it actually runs rather than how it was designed. A Green Associate question may contrast a new-construction BD+C metering prerequisite (install meters, commit to report) with an O+M emphasis on continuous tracking and corrective action over the building's operating life.

Common Traps

• Building-level metering is a prerequisite (required); submetering is an optional credit (earns a point).
• Metering reveals use but never reduces it; pair measurement with a reduction action.
• The five-year data-sharing commitment is part of the prerequisite - it is not optional once you choose to certify.
• Submetering two or more subsystems is the credit threshold; a single submeter is not enough for the point.
• A whole-building meter satisfies the prerequisite but cannot isolate which subsystem drives high use - that diagnostic job belongs to submeters.
• Cross-category links are real but the answer still follows the primary lever the stem names; do not pick "Sustainable Sites" for a question whose verb is "track water use."

Close the chapter by rehearsing the full arc: identify the end use, reduce demand, substitute nonpotable water where quality and code permit, meter to make use visible, and correct leaks or anomalies. That five-step arc, anchored to the EPAct 1992 and WaterSense baselines and the 20%/30%/whole-building prerequisite floors, will resolve the large majority of Water Efficiency questions you meet on the LEED Green Associate exam.