Ontario EWRB reporting: a step-by-step data guide for 2026 and 2027

Ontario's Energy and Water Reporting and Benchmarking program (EWRB) has been running long enough that most large-building owners know it exists. What still goes wrong every spring is the data: a gas account nobody mapped, a tenant meter that never made it into the whole-building total, a water meter reported in the wrong unit. The submission goes in, but the numbers behind it do not survive a verifier or a comparison against last year.

This guide covers the obligation for the 2026 and 2027 cycles, the Portfolio Manager workflow step by step, verification for larger buildings, the Toronto overlap, the data problems behind wrong submissions, and a month-by-month calendar.

Who must report, and who is exempt

Under O. Reg. 506/18, owners of buildings that are 50,000 square feet and larger must report their building's energy and water use once a year. The province lists four standing exemptions: buildings that are publicly owned, buildings where at least 50 percent of the gross floor area is occupied by a public agency, buildings where at least 10 percent of the area is a data centre, television studio or trading floor, and buildings where at least 10 percent is used for manufacturing or processing that governs the environmental conditions. Each of those is stated on the Ontario EWRB page, and the size threshold applies to the whole property, not to a single tenant's space.

The same page lists one-year exemptions: an owner declared insolvent during the reporting year, a property subject to a tax arrears certificate, power of sale, foreclosure or writ of execution, and a building newly constructed with a certificate of occupancy issued in the reporting year. Document the basis before the deadline, not after a follow-up.

The deadline, the reporting year, and the EWRB ID

The report covers January 1 to December 31 and is due July 1 of the following year, so the 2026 cycle covers calendar 2025 and the 2027 cycle covers calendar 2026. Every property reports under an EWRB ID, a unique six-digit number assigned by the Ministry of Energy and Mines. Submissions are made through ENERGY STAR Portfolio Manager, and the province asks for usage data for all forms of energy the building uses (electricity, natural gas, diesel, fuel oil and so on) plus water.

The Portfolio Manager workflow, step by step

Portfolio Manager serves both the province and Toronto, but it will accept incomplete data and give you a number anyway. Work through it in this order.

1. Set up the property. The ENERGY STAR data collection worksheet asks for property name, address, total gross floor area, irrigated area, year built, occupancy and number of buildings, and states that all properties are eligible to receive metrics such as source EUI by providing gross floor area and 12 months of energy usage. Gross floor area is the denominator for every intensity metric, so measure it once and document how.
2. Create one meter for every fuel and for water, each with the correct unit. A building that heats with gas and reports only electricity is reporting part of its energy use.
3. Enter whole-building data, including tenant meters. Toronto lists the performance data as monthly electricity, natural gas, district energy and water, and the province requires whole-building figures. Tenant-held accounts need the tenant's data or consent, and that is the most common reason a submission is short.
4. Enter 12 consecutive months. The worksheet is explicit that metrics depend on 12 consecutive months of energy data. Bills that span month ends are fine; gaps and overlaps are not.
5. Run the data quality checker, fix every alert, then share with the province. Toronto buildings share the same property with the City, so one clean property serves both submissions.

Verification for buildings of 100,000 square feet and larger

Larger buildings carry an extra step. The province requires buildings of 100,000 square feet or larger to have their data verified by a certified professional in the first year of reporting, then every subsequent five years. Toronto states the same cadence for its own requirement and lists who qualifies: professional engineers, architects, and holders of specified certifications including CEM, BOC, CMVP, CBCP, CEA, CMI, BETC and BSS-O, or licensed condominium managers. The City also allows a partial exemption from its own attestation if the building was verified within the prior five years for the provincial requirement, so keep the verification record where you can find it.

A verifier will ask for the bills behind the numbers, the meter-to-account map, the floor area basis and any adjustments for estimated reads or missing tenant data. If those live in one place, verification takes an afternoon; in six inboxes, a month.

How Toronto's Chapter 367 overlaps

Toronto buildings report twice from one dataset. The City's page states that the deadline for City submissions is July 2 and the deadline for Ontario submissions is July 1, with both reporting the same calendar-year data; 2025 data was due July 2, 2026. The bigger change is scope: from 2027, buildings of 929 square metres (10,000 square feet) and larger must report to the City, after Council postponed the first reporting year for the 10,000 to 49,999 square foot category to 2027. Those smaller buildings report to Toronto only, since the provincial threshold stays at 50,000 square feet. See Toronto's 2027 energy reporting rule for newly in-scope owners, and the energy-reporting wave building toward 2027 for the wider set of dates.

Toronto also lists the descriptive fields it wants: address, property type, gross floor area, construction year, suite count and tax roll number. Condominium owners should read the City page's note on how units and common areas are assessed against the threshold.

The data problems that cause wrong or rejected submissions

Almost every EWRB problem is a data problem that existed months before the deadline. The tool did not cause it; the bills did.

• Gaps: a meter with 11 months because one bill was never received or was filed under another site.
• Overlaps: two bills covering the same days after a rebill or account change, double-counting that period.
• Estimated reads: an estimated bill followed by a true-up looks like a spike and a dip, and distorts the profile a verifier compares against.
• Unit mix: gas in cubic metres on one account and gigajoules on another. Portfolio Manager converts if you pick the right unit; it cannot tell you when you picked the wrong one.
• Missing tenant data: Toronto lists withheld tenant consent as grounds for a partial exemption on electricity, but you have to show you asked.
• Floor area drift: an area re-measured for a lease and entered without updating the reporting basis, which shifts every intensity metric.

Ontario has an advantage here. The Green Button Alliance describes Download My Data as a select-and-download of electricity, gas or water usage in an industry-standard XML format, and Connect My Data as authorized applications retrieving data at 5-minute, hourly, daily or monthly intervals. For an EWRB filer, that means monthly totals per meter straight from the provider's system rather than from re-keyed PDFs; our plain guide to Green Button in Ontario covers how to get it. Where it is not available, bills remain the source and need to be read completely and checked before they reach the tool. Automating Portfolio Manager explains how monthly updates replace the annual scramble, and the data quality checklist for Portfolio Manager lists the alerts to clear before you share.

A month-by-month prep calendar

The reporting year closes December 31 and the report is due July 1. Six months is plenty if the work starts in January and not enough if it starts in June.

• January: confirm the property list against the threshold, including Toronto buildings entering the 10,000 square foot tier for 2027. Confirm EWRB IDs. Send tenant consent requests.
• February: reconcile the meter-to-account map: every fuel, every water service, every account tied to a Portfolio Manager meter.
• March: load January through December for every meter. Flag gaps, overlaps and estimated reads and chase missing bills.
• April: resolve estimated reads against true-ups, fix units, confirm gross floor area. Book the verifier if this is a verification year.
• May: run the data quality checker, clear every alert, assemble the verifier package.
• June: complete verification if required, share with the province and, in Toronto, with the City. Submit before the last week.
• July onward: keep monthly data flowing so next year's report is a review, not a rebuild.

How MartinAI fits

MartinAI does not file anything with the province or the City; the owner does, through Portfolio Manager. What it does is prepare and validate the data that goes in: it reads every electricity, gas, district energy and water bill for every account, normalizes units, tests the 12-month series for gaps, overlaps and estimated reads, keeps each figure tied to its source document, and delivers whole-building monthly totals ready for the tool. Our setup guide to Portfolio Manager in Canada covers the tool side.

EWRB is a data obligation dressed as a reporting one. Get the meter map, the tenant data and the 12 clean months right, and the July deadline becomes one of the easier items on the facilities calendar.