How Should Submetering Be Designed for Accurate Tenant Billing?

Submetering design provides tenant-level metering of electricity, water, gas, or thermal energy accurate enough for billing. It covers revenue-grade meter selection, proper CT sizing and installation, meter placement for access and accuracy, and the data infrastructure that carries readings to the billing process. Submetering exists for two reasons: fairness (tenants pay for what they use) and behavior (metered tenants use less — the data consistently shows it). Both reasons depend entirely on the numbers being right. A submetering system that produces questionable data is worse than no submetering, because it generates disputes instead of savings.

The design starts with the lease language: what's billed, how it's calculated, and what accuracy the lease or local law requires. That determines the meter accuracy class — revenue grade where billing demands it — and the meter features needed (demand metering, time-of-use, data logging). Then the physical design: CTs sized to the tenant's actual load (not the panel rating), meters located for access with proper clearances, and the communication network designed to carry every meter's data to the collection point. For water and thermal energy, the plumbing design includes meter locations with straight-pipe runs and isolation valves. I coordinate submetering with the electrical and plumbing designs early because meter locations affect panel layouts and piping routes.

Billing accuracy is a trust issue. These rules keep the numbers defensible.

• Start from the lease: billing requirements determine accuracy class before any equipment is selected
• Size CTs to the load: tenant's actual demand profile, not the breaker rating — accuracy lives here
• Locate for access: common-area meter locations with working clearance, never buried in tenant space
• Design the data path: networked meters to a collection system — metering without data infrastructure is incomplete
• Document everything: meter schedules, CT ratios, and calibration records that survive a billing dispute