If you build energy software, run an energy program, or manage a portfolio of buildings in Ontario, you have probably heard that utilities across the province now offer Green Button. The rule behind that is Ontario Regulation 633/21, the Energy Data regulation. It is short, but it changed how consumption data moves between utilities, their customers, and the third parties those customers authorize. This guide walks through what the regulation actually requires, the standard it relies on, and what it does and does not do for you as a data user.
The goal is a practical read, not a legal opinion. Where a claim rests on a source, the source is linked inline so you can check the text yourself.
What O. Reg. 633/21 is
O. Reg. 633/21 is a regulation made under Ontario's Electricity Act, 1998. The full text is published on Ontario's e-Laws site as O. Reg. 633/21: Energy Data and is also available on CanLII. It was filed in 2021 and sets out an obligation for electricity distributors and natural gas utilities to give customers a standard way to access and share their own energy data.
The Green Button Alliance, the industry body that maintains the Green Button certification program, described the regulation at the time as the first of its kind in North America to require utilities across a whole province to implement Green Button. Its announcement is a useful summary: Ontario passes regulation that empowers energy users with Green Button energy data access and sharing.
What it requires of utilities
The regulation points to a technical standard rather than describing a data format itself. Ontario utilities were required to implement Green Button solutions that follow the North American Energy Standards Board (NAESB) REQ.21 Energy Services Provider Interface (ESPI) standard, version 3.3, by November 1, 2023. The Green Button Alliance set this out in its release, Ontario's new energy data regulation requires utilities to implement Green Button.
That standard defines two delivery methods, and the regulation covers both:
- Download My Data (DMD). The customer signs in to the utility portal and downloads a standardized file of their own usage, in the Green Button XML format. It is a manual, one-time export.
- Connect My Data (CMD). The customer authorizes a named third party to receive an ongoing feed of their data through an API, using OAuth 2.0 for the authorization step. No file passing, and no shared password.
The Green Button Ontario FAQ walks through both methods in the Ontario context. For a data user, CMD is the interesting one, because it turns a customer's consent into a repeatable data connection rather than a spreadsheet emailed once.
Certification and who is covered
The regulation does not just ask utilities to publish data in a loosely similar shape. Utility platforms are tested and certified by the Green Button Alliance against the ESPI standard. In early 2024 the Alliance announced that 55 Ontario-based utility platforms were Green Button certified, covering electricity distributors and natural gas utilities across the province.
London Hydro reported being the first utility to satisfy the regulation, and larger distributors such as Alectra Utilities publish their Green Button offering for customers. Certification matters to data users because it raises the odds that two utilities present the same data types in the same structure, which is the whole point of a standard.
The regulation does contemplate exemptions. Some very small entities, and utilities without the metering infrastructure to support the standard, are treated differently. If you are building a coverage map, do not assume every single distributor and reseller in Ontario exposes a certified CMD endpoint. Read the regulation's application section on CanLII and confirm per utility.
What the regulation does not do
It helps to be clear about the limits, because these are where projects get stuck.
- It does not make the customer's data public. Access still depends on the customer authorizing it, either by downloading their own file or by granting a third party a CMD authorization.
- It does not standardize the utility registration process. Each utility can require a third party to register and be approved before it can receive CMD feeds, and the paperwork and lead time vary.
- It does not standardize historic bill PDFs or older data that predates a customer's smart meter. The regulation is about the standard interface going forward, not a full history in every case.
- It does not remove the operational work of maintaining many separate utility connections, tokens, and refresh cycles.
So the regulation gives you a common target format and a legal expectation that utilities offer it. It does not hand you a single door into every utility in Ontario.
What this means for a data user
For most software teams and consultants, the practical read is this. Green Button data from a certified Ontario utility arrives as ESPI XML with predictable structures for usage points, meter readings, and interval blocks. Once you can parse one utility's output, you can parse most, which is a real reduction in per-utility integration work compared with the era of custom scrapers and inconsistent CSV exports. The Green Button developer documentation describes the data model and the exchange roles in detail.
The remaining work is coverage and operations: getting registered with each utility that requires it, managing customer authorizations, handling token refreshes for CMD, and reconciling the handful of utilities that fall under exemptions or expose quirks in their certified platforms.
Where a connector fits
This is the part a service like EZGB is built for. EZGB collects Green Button data across many utilities using both Download My Data and Connect My Data, so a single integration on your side can reach data from a range of Ontario distributors and gas utilities instead of one at a time. For customers whose older records only exist as bill PDFs, EZGB also turns those bills into structured data, which fills the gaps the standard interface does not reach. The result is a consistent stream you can pull through an API and feed into your own application, without your team maintaining a separate connection to every utility.
O. Reg. 633/21 did the hard part of setting a common standard and making Ontario utilities offer it. The work that remains for a data user is coverage, consent, and upkeep across dozens of utilities. Understanding what the regulation requires, and what it leaves to you, is the first step to planning a data pipeline that holds up in production.
Source: canlii.org