A building has one electricity account with the local distributor, but forty tenants who each use a different amount. Submetering is how the building tells those two facts apart. It is a familiar idea in apartment buildings, condominiums, plazas and industrial parks, and it is usually introduced for billing reasons. What owners discover afterwards is that the submeters are also the only place their building's consumption exists at a useful resolution, which makes them the starting point for every energy report they will be asked to produce later.
This guide covers what submetering is, how it differs from the bulk meter the utility reads, what typically gets submetered, who is allowed to install and bill for submeters in Ontario, and what to do with the data once it exists. If you already run submeters and the problem is getting the readings into a usable dataset, the companion guide on submetering and interval data management picks up where this one ends.
What submetering means
The local distribution utility installs one meter at the property. That meter is the point where electricity legally changes hands, and it produces the bill the building owner receives. A submeter sits downstream of it and measures a slice of that same supply: one apartment, one commercial unit, one floor, one tenant's equipment, one electric vehicle charger. The distributor does not read submeters and does not bill from them. They exist for whoever owns the building.
Everything a submeter measures has already been measured once by the utility meter upstream. That is the source of the most common surprise in submetering projects: the submeters almost never add up exactly to the utility bill. Common area lighting, elevators, pumps, parking and mechanical loads are usually not submetered, and the gap between the sum of the submeters and the master meter is house load. A building that plans for that gap has a working allocation model. A building that does not plan for it spends the first year arguing about it.
Bulk metering and submetering side by side
| Bulk metering | Submetering | |
|---|---|---|
| Who reads the meter | The local distribution utility | The building owner or a licensed provider acting for them |
| Who gets the bill | The building owner, one bill for the property | Each unit, based on what that unit used |
| How tenants pay | Built into rent or common expenses, usually as a flat share | In proportion to actual consumption |
| Visibility for the occupant | None, the occupant cannot see their own use | Their own usage and their own bill |
| Data available to the owner | One property-level total per billing period | Unit-level data, often at interval resolution |
| Typical effect on consumption | No signal to reduce use | Occupants see and respond to their own use |
The last row is the reason most owners look at submetering in the first place. When consumption is buried in rent, nobody in the building has a reason to change anything. When each unit gets its own bill, behaviour follows the bill. The second reason is fairness: under bulk metering, a small unit that is empty all day subsidises a large unit running equipment around the clock.
What gets submetered
- Electricity, the most common by a wide margin, and the only one with a dedicated licensing regime in Ontario.
- Water, often introduced alongside electricity in multi-residential buildings.
- Natural gas, where suites have separate gas appliances or heating.
- Thermal energy, meaning heating and cooling delivered from a central plant, measured in units of energy rather than fuel.
- Electric vehicle charging, which has become its own category as parking spaces get energised and the cost has to land on the driver.
A building rarely submeters all of these at once. The practical sequence is to start with the commodity that carries the largest cost and the clearest per-unit variation, which in most Ontario buildings is electricity, then add others when the meters are already being touched for another reason. If you are collecting more than one commodity, the guide on natural gas, water and propane data alongside electricity covers how to keep the units and periods straight once the data arrives.
Who installs, reads and bills submeters in Ontario
In Ontario, billing a tenant from a submeter is a regulated activity, not a private arrangement between a landlord and an occupant. The Ontario Energy Board (OEB) describes unit sub-meter providers, or USMPs, as companies that provide electricity metering and billing services to customers in multi-unit buildings, and states plainly that the OEB licenses USMPs and establishes and enforces the rules that protect those customers.
The operating rules live in the Unit Sub-Metering Code, which sets the minimum conditions and standards a licensed provider has to meet. The OEB summarises the scope as business practices and customer service standards covering bill issuance and payments, security deposits, arrears payment agreements and the disconnection process. The Code also requires providers to publish Conditions of Service, so a resident can read the operating practices that apply to them. Applications, fees and the licence process itself are set out on the OEB's unit sub-metering licence page.
Two consumer protections matter for anyone modelling the economics. The OEB states that utility charges are passed through to the resident with no mark up, so submetering is a cost allocation mechanism rather than a revenue line on the electricity itself. It also states that a resident cannot independently choose an electricity price plan, because that decision is made for the building as a whole by the principal consumer. Residents who qualify keep access to bill assistance programs, and the Ontario Electricity Rebate is applied.
Requirements for new construction and for converting an existing bulk-metered building change over time, and they depend on the building type and when it was built. Confirm the current position with the OEB or your legal advisor before committing to a retrofit rather than relying on an article, including this one.
When a building actually needs submetering
Submetering earns its cost in a few recognisable situations. The clearest is a multi-tenant building where consumption varies a lot between units and the owner is absorbing that variation. The second is a building where the owner wants tenants to respond to their own use, which only happens when tenants can see it. The third is less about billing: a portfolio owner who has to report energy performance per building, or per unit, and currently has nothing below one utility bill per property.
It is worth being honest about when it does not pay. A small building with uniform units and low consumption variation may never recover the installation and ongoing service cost through fairer allocation alone. A building about to undergo a major electrical retrofit should sequence the meters into that work rather than install twice. And a building whose real problem is that nobody knows what the property consumes month to month does not need submeters yet, it needs its existing utility data collected properly, which is a much smaller project.
What happens to the data after the bill
Submeters produce far more data than a bill needs. A unit bill needs one number per period. The meter itself typically records interval data, often hourly or finer, and that record answers questions a bill never can: when the building peaks, whether a unit's overnight load is normal, whether a vacant unit is still drawing power, whether a retrofit changed anything, and what the building looked like before and after a tenant changed their operation.
This is where most submetering programs stall. The billing system holds the readings, the reports are built for billing, and anyone who wants the underlying data ends up exporting spreadsheets by hand. The difference between billing data and interval data, and when each one is the right input, is covered in interval data and billing data.
Getting submeter and utility data into one pipeline
Most portfolios end up with two parallel data problems. Submeters describe what happens inside the building. The distributor's meter describes what the building bought, and that is the number that appears in financial reporting and in any mandatory energy report. Keeping those two in separate systems means every question that spans them becomes a manual reconciliation.
The utility side of that is a solved problem in Ontario. Distributors publish interval and billing data in the Green Button format, which is standardized across utilities, so one ingestion path covers many accounts. EZGB collects it across the utilities listed on the supported utilities page and delivers it in one shape, which gives you a stable base to line submeter readings up against. For a portfolio view of that approach, see collecting utility data across a property portfolio; for the landlord case specifically, see utility data for residential landlords and multifamily portfolios.
A practical order of work: get the property-level utility data flowing automatically first, because it is the number everyone else asks for, then bring submeter exports alongside it, then reconcile the house load gap once rather than every month. Pricing and account options for the utility side are on the pricing page.
Submetering decisions look different when the building is social or affordable housing, where the resident bears the cost and the provider answers to a funder. The guide on utility data for non-profit and affordable housing works through that case.
Frequently asked questions
Is submetering the same as a smart meter?
No. A smart meter is the utility's own meter at the property boundary, and the utility reads and bills from it. A submeter measures a portion of what that meter already measured, and it belongs to the building side of the connection.
Can a landlord bill tenants from submeters without a licence?
In Ontario, unit sub-metering is a licensed activity and the OEB licenses the providers who carry it out, with the Unit Sub-Metering Code setting the standards they follow. Anyone considering billing from submeters should confirm their position with the OEB before starting.
Will the submeters add up to the utility bill?
Usually not, and that is expected. Common area loads such as lighting, elevators, pumps and parking are generally not submetered. Plan the allocation of that house load before the first bill goes out.
Do I still need the utility's data if I have submeters?
Yes. The utility meter is the number that appears on the invoice the building pays and in most reporting programs. Submeters explain how that total was distributed inside the building.
What resolution should I keep?
Keep the finest resolution the meter produces, usually hourly or better, and aggregate up when reporting. Aggregated data cannot be disaggregated later, so anything you discard is gone.
Distributors publish their own guidance for multi-unit sites. Enova Power, for example, has a suite metering page for developers alongside its Green Button programme, covered in the guide to Enova Power Green Button usage data.
Sources
- Ontario Energy Board, Understanding Electricity Unit Sub-Meter Providers (USMP): https://www.oeb.ca/consumer-information-and-protection/oebs-consumer-protection-role/understanding-electricity-unit
- Ontario Energy Board, Unit Sub-Metering Code: https://www.oeb.ca/regulatory-rules-and-documents/rules-codes-and-requirements/unit-sub-metering-code
- Ontario Energy Board, Apply for a unit sub-metering licence: https://www.oeb.ca/applications/how-file-application/apply-licence/unit-sub-metering
Source: oeb.ca