Electricity submetering means putting a meter behind the utility's meter, so consumption can be measured for a part of a building rather than the whole of it. A landlord uses it to bill tenants for what they actually use. A facility team uses it to find out which floor, which tenant or which chiller is responsible for a load. Those are different goals, and they lead to quite different installations.
The confusion worth clearing up first is that a submeter used for billing is a regulated device, and a submeter used only for information is not. Getting that the wrong way round is expensive in one direction and wasteful in the other.
What a submeter measures, and what it does not
A modern electricity submeter records kilowatt-hours at an interval, usually fifteen minutes or an hour. Better units also record demand in kilowatts, and three-phase units record per-phase current and voltage, power factor and sometimes harmonics.
What it does not know is anything about money. A submeter produces quantities. Turning those quantities into a charge needs a rate structure applied to them, and on a commercial account that rate structure is more complicated than a price per kilowatt-hour: there is usually a demand component, a fixed delivery charge, and in some markets a global adjustment or capacity charge that depends on when you used power rather than how much.
- Energy, in kilowatt-hours, accumulated over each interval.
- Demand, in kilowatts, usually the highest average over a fifteen-minute window in the period.
- Timestamps, which matter more than people expect, because a meter whose clock has drifted puts consumption in the wrong pricing window.
- Interval resolution, which sets the ceiling on what analysis is possible later: hourly data cannot show you a fifteen-minute demand peak.
If you bill from it, the meter is regulated
In Canada, a meter used to work out a charge for electricity is covered by federal law. The Electricity and Gas Inspection Act is direct about it. Section 9(1) provides that where a contractor or purchaser intends to use a meter "for the purpose of obtaining the basis of a charge for electricity or gas supplied by or to him, the meter shall not, until it has been verified and sealed in accordance with this Act and the regulations, be put into service".
Section 9(4) adds the approval requirement: no meter is verified under the Act "until it or the class, type or design of meter to which it belongs has received the approval of the director". In practice that means the meter model has to be approved, the individual unit has to be verified and sealed, and it has to be reverified on a schedule.
"A meter you bill from must be an approved model, verified and sealed before it goes into service. A meter you only watch has no such obligation."
This is the single most useful thing to know before buying hardware. If the submeters are going in so that the facility team can see which tenant runs their air handling all night, any accurate meter will do. If they are going in so that the tenant gets an invoice, the specification is narrower and the installation cost is higher. Measurement Canada publishes the approval and verification requirements that apply.
Ontario adds a second layer: suite metering
Ontario regulates the business of submetering separately from the hardware. A company that meters and bills individual units in a multi-unit building is a unit sub-meter provider, and it needs a licence from the Ontario Energy Board.
The OEB's own guidance on unit sub-meter providers sets out what that means: "The OEB licenses USMPs, and establishes and enforces rules and laws that protect customers." Licensed providers must follow the Unit Sub-Metering Code, which covers "bill issuance and payments, security deposits, arrears payment agreements and disconnections process requirements".
Two details in that guidance surprise people, and both are worth knowing before you sign anything.
- A provider's "fees and service charges are not regulated by the OEB". The billing conduct is regulated. The administration fee is not.
- Individual occupants cannot choose their own electricity price plan. Only the principal consumer, meaning the building owner or manager, makes that choice for the building.
- The winter disconnection ban that applies to utility customers does not apply to multi-unit buildings served this way.
If you are the building owner, that third point is a reason to read the code rather than assume the protections you are used to carry over. If you are the occupant, it is a reason to read your lease.
What the data is good for once you have it
Allocating cost accurately
The default alternative to submetering is allocating the whole-building bill by floor area, which is fine when every tenant uses power the same way and wrong the rest of the time. A restaurant and a law office on the same floor plate do not have the same load, and an area-based split moves money from one to the other every month.
Finding the load nobody knew about
Interval data from a submeter shows a base load, which is the consumption that continues when the space is empty. A base load that is a high fraction of the daytime peak is the clearest single indicator that something is running when it should not be. You cannot see it in a monthly whole-building bill, and you can see it immediately in a week of interval data.
Verifying that a retrofit worked
Measuring a specific piece of equipment before and after a change is far more convincing than watching a whole-building meter and hoping the weather cooperated. Submetering the affected system is what makes that comparison possible.
Recharging a shared service
Buildings with a shared chiller, a shared compressor or a shared electric vehicle charging bank have to divide a cost that is genuinely joint. A submeter on the shared asset at least makes the total defensible before the split rule is argued about.
The data problems that show up in month two
Submetering projects rarely fail on hardware. They fail on the data handling afterwards, and the failures are consistent enough to list.
| Problem | What it looks like | What fixes it |
|---|---|---|
| Clock drift | Consumption lands in the wrong pricing window; sums do not match the interval detail | Time sync on install, then a periodic check |
| Missing intervals | A gap in the series, then a total that quietly undercounts | A read-completeness check per meter per period, not per portfolio |
| Meter resets | A negative or absurd interval when a cumulative register rolls over | Register-aware processing rather than raw differencing |
| Submeters that do not sum to the main meter | Tenant bills total less than the utility bill and nobody knows where the rest went | Reconciliation against the utility meter every period, with the difference reported rather than absorbed |
| Nobody owns the export | Data sits in a gateway until someone needs it and the retention window has passed | A scheduled export into somewhere durable, with the raw file kept |
That last row is the one that costs the most. A submetering system whose data lives only in the vendor's portal is a rental of your own measurements. Getting a periodic export into your own storage, in a format you can still read in five years, is cheap to set up and impossible to do retroactively.
How submeter data sits alongside utility data
Submeters tell you how consumption is distributed inside the building. They do not tell you what the utility charged, and they cannot, because the charge depends on a rate structure the meter has never seen. The two datasets answer different questions and both are needed: the utility bill is the truth about cost, and the submeters are the truth about who caused it.
Reconciling them is the work that makes both useful. If the submeters account for 88 percent of the metered consumption, the missing 12 percent is either house load, a meter that stopped reporting, or a circuit nobody metered, and knowing which of the three matters. We cover the wider picture in what submetering is and when a building needs it and the mechanics of handling interval data in submetering and interval data management.
For the whole-building side of the record, Ontario's utility data-sharing rules give account holders a route to their own utility interval data without installing anything, which we explain in how to get utility data from Ontario utilities.
A short specification checklist
- Decide first whether you will bill from these meters. That single answer sets the hardware specification and most of the cost.
- If billing, confirm the meter model is an approved type and plan for verification, sealing and reverification.
- Specify the interval resolution you want to keep, not just the one the meter can record. Fifteen minutes is the useful default.
- Require a scheduled data export to storage you control, in a documented format, and test the export before the installer leaves.
- Ask how meter resets and gaps are handled, and get the answer in writing.
- Plan the reconciliation against the utility meter as part of the monthly routine, not as an annual clean-up.
None of that is exotic, and all of it is much easier to specify before installation than to retrofit afterwards.
Frequently asked questions
Does an electricity submeter need to be approved if we bill tenants from it?
Yes. The Electricity and Gas Inspection Act requires a meter used to obtain the basis of a charge to be verified and sealed before it goes into service, and the meter's class, type or design must be approved. A submeter installed only to inform a facility team, with no billing attached, is not subject to those requirements.
Do we need an Ontario Energy Board licence to submeter our own building?
Metering and billing individual units in a multi-unit building in Ontario is the activity the OEB licenses as a unit sub-meter provider. Most building owners contract a licensed provider rather than becoming one. If you are considering doing it yourself, read the Unit Sub-Metering Code first, because it governs billing, deposits, arrears and disconnection.
What interval resolution should we specify?
Fifteen minutes is the useful default, because that is the window most commercial demand charges are measured over. Hourly data cannot show you a fifteen-minute peak, and once the data is recorded at a coarse resolution the detail is gone for good.
Why do our submeters not add up to the utility meter?
Three usual reasons: house or common-area load that nobody metered, a circuit that was left out of the design, or a meter that has stopped reporting. The difference should be calculated every period and reported rather than absorbed, because a growing gap is the signal that a meter has failed.
Can we get interval data without installing submeters?
For the whole building, often yes. Utility data-sharing standards give the account holder access to their own interval data from the utility meter. That covers the building total but tells you nothing about how consumption is distributed inside it, which is what submeters are for.