Sub-meter, check meter or revenue meter?

A revenue meter is the utility's meter at the point of supply — it measures what the utility sells you and generates the bill you receive. A sub-meter sits downstream, inside your installation, and measures how that supply is divided among tenants, departments, floors or machines. The utility owns and controls the first; you own the second.

A check meter is installed by the consumer alongside the utility's meter for the sole purpose of comparing readings. It is not used to bill anyone. Its job is to give you an independent number when you suspect the supply meter is reading high, or when you want assurance before disputing a bill. To be useful it has to be at least as accurate as the meter it is checking.

In commercial arrangements, yes — sub-billing tenants for their measured consumption is normal practice and is governed by the terms of the lease or service agreement rather than by utility regulation. What matters practically is that the meter is accurate enough to survive being challenged, and that the data is auditable. Class 0.5S with interval data and a clear record is what makes that defensible.

A sub-meter installed inside your own installation, downstream of the supply point, is your equipment and is governed by your commercial agreements. It is not part of the utility's regulated metering. Revenue metering at the point of supply is a different matter entirely and is subject to utility and statutory requirements — which is why the two categories should not be conflated when specifying.

Class 0.5S if you are invoicing anyone off it. The moment a reading becomes a charge, someone has a reason to question it, and a recognised accuracy class is what turns your number into evidence. If the sub-meter is purely for internal visibility — spotting idle load, tracking a department's trend — Class 1 is a reasonable saving.

If you want to know how much you used, the main meter is enough. If you want to know where it went, it is not. No amount of analysis of a single incoming total will tell you which line, which chiller or which tenant is responsible — that requires measurement at the point you care about. This is the single most common reason energy projects stall after the first month.

It depends on what decisions you intend to make. A common starting point is the incomer plus the major loads — compressed air, HVAC and chillers, and each significant production line — which for a mid-sized plant tends to land somewhere around ten to twenty points. Start with the loads big enough to act on, and add granularity where the data shows it is worth having.