Back Bay Condo Buildings Now Have a Public Emissions Number. The Deadline That Counts Is 2030.

On September 30, 2026, Boston published the first BERDO data disclosure that measures buildings against an emissions limit. It lists covered condominium associations by name and address, along with each building's compliance status. For buildings whose reports had cleared review, it also shows 2025 energy use, fuel mix and carbon emissions per square foot. Rows marked Extension, Pending Revisions or Pending Review don't have usage figures yet. A buyer comparing two Back Bay buildings can now see a figure that the association's budget, the listing and the resale certificate never showed.

For most Back Bay condo buildings, the status column will look reassuring. Many say "N/A until 2030." That label means the clock hasn't started yet, and for nearly every smaller building we pulled, its 2025 emissions already sit above the limit that applies once it does.

Building size sets the deadline

The disclosure's data dictionary says residential buildings with 35 or more units on a tax parcel first had to meet an emissions standard with their 2025 data, reported in 2026. All other covered buildings first face a standard with their 2030 data. The ordinance defines its residential tiers by both unit count and square footage, so the two documents don't use exactly the same terms. In practice, the file's "First Emissions Compliance Year" column shows which group a building is in. A 40,203-square-foot multifamily building at 191 Commonwealth Avenue, for example, is listed in the 2030 group.

The limits themselves are set in the ordinance text. For multifamily housing, the standard is 4.1 kgCO2e per square foot per year for 2025 through 2029. It falls to 2.4 for 2030 through 2034, then to 1.8, 1.1 and 0.6 in each later five-year period, and reaches zero in 2050.

So a large Back Bay building got five years under a relatively loose limit. A brownstone-conversion association with 20 or 30 units skips that period and starts at 2.4. In the 2025 data, that is a bar most of them don't clear.

What the first disclosure shows on named Back Bay buildings

These are the 2025 figures as reported in the September 30, 2026 file. The fuel column comes from the energy-use fields in each building's row.

Of the six 2030-group buildings in the table, five reported 2025 intensities above 2.4. The only one under it, 259 Beacon, also comes in below the 1.8 standard that follows in 2035. The two large buildings that pass today, Copley Condominium Trust and Fifty Commonwealth, are both above 2.4 as well. Their status says compliant, but at 2025 usage levels neither would meet the 2030 standard.

The city calls this disclosure provisional. Some buildings were still on extensions through October 15, others are marked "Pending Review from BERDO Team" and are not considered out of compliance, and the file is due to be updated. One Back Bay example is the condo association at 184-190 Commonwealth Avenue, which reported 3.9 and is listed as under review. The data dictionary defines "Action Needed" as emissions above the standard, with the owner required to buy renewable energy or make Alternative Compliance Payments to come into compliance.

Fuel type decides whether the gap closes without a retrofit

Two buildings at the same intensity today may be headed in different directions, because BERDO doesn't treat all energy the same way over time.

The city's BERDO Emissions Factors List, last updated September 18, 2026, sets fixed factors for fuels burned on site: 53.11 kg per mmBtu for natural gas and 74.21 for No. 2 fuel oil. Grid electricity gets a projected factor that the city expects to decline, from 249 kg per MWh for 2025 to 150 by 2050. The projection rises from 242 in 2026 to 265 in 2027. BERDO applies the factor for the relevant year to electricity use and divides total emissions by floor area. If usage stays the same, a lower grid factor lowers an all-electric building's reported intensity.

The table shows three cases:

1. Copley Condominium Trust reported no gas or oil use, so all of its 2.6 comes from electricity. Its path toward the 2030 limit depends partly on the regional grid.
2. Fifty Commonwealth reported 172,680 kg of its 194,446 kg total from natural gas, about 89 percent. Unless the building changes how it heats, that share stays at the same factor.
3. Beacon On The Charles reported 154,724 kg of its 169,168 kg total from No. 2 fuel oil, about 91 percent, at a higher factor than natural gas.

Fuel type also limits the shortcuts. The city's guidance for buildings above their limit says eligible renewable energy purchases can offset electricity emissions, while Alternative Compliance Payments can cover emissions from any source. In a building heated mostly by gas or oil, renewable energy credits can only reach the small electric share. The rest is handled by paying or by changing the equipment.

The payment math at today's rate

The Alternative Compliance Payment is currently $234 per metric ton of CO2e over the limit, paid every year. The ordinance requires the BERDO Review Board to review that price every five years and allows it to be changed through regulations. All payments go to the Equitable Emissions Investment Fund.

The figures below are hypothetical buildings based on the size and intensity ranges in the table. They aren't estimates for any listed association. Each one holds emissions constant and uses today's $234 rate, and none accounts for future grid factors, renewable purchases, efficiency work or a change in the rate.

• A 70,000-square-foot building at 4.5. Against the 4.1 limit, it would be about 28 metric tons over, or roughly $6,600 a year. Against 2.4, it would be about 147 tons over, or roughly $34,400 a year.
• A 67,000-square-foot building at 2.9. About 34 tons over 2.4, or roughly $7,800 a year.
• A 16,000-square-foot building at 5.0. About 42 tons over 2.4, or roughly $9,700 a year.
• A 24,000-square-foot oil-heated building at 7.1. About 113 tons over 2.4, or roughly $26,400 a year.

Spread over an association's units, payments at this scale may look modest next to a capital project. That comparison only holds for one five-year period. Each later standard is lower, so the same building pays for more tons in every period through 2050, at whatever rate the Review Board sets by then. None of our sources reported a Back Bay association levying a BERDO-related assessment, and none of these figures should be read as a cost any named building has incurred.

Who carries it

The city's condo webinar assigns reporting, third-party verification and emissions compliance to the condominium association or board of trustees. Handing the work to a property manager doesn't move that responsibility. The same presentation lists association funds, special or supplemental assessments, and condominium loans as ways boards pay for common-area work. These are funding routes, not anything BERDO requires.

Enforcement escalates in steps. For the larger residential tier, the city's 2026 regulations document lists daily penalties of $300 for reporting violations and $1,000 for emissions violations. For the smaller covered residential tier, the figures are $150 and $300. A building gets a notice of probable violation at least 60 days before a notice of violation, then 30 more days to correct before fines are assessed.

The city also created a short-term hardship option covering 2025 through 2027 for qualifying under-resourced buildings, including condos and co-ops that meet assessed-value or resident-income tests. As of the city's September 2, 2026 guidance, applications for flexibility measures covering 2025 and 2026 emissions were closed. Two deadlines remain this year for 2025 compliance. Purchases through the city's REC Connector close October 31, 2026, and qualifying renewable energy credits have to be retired by December 31, 2026.

For buyers comparing buildings, these figures sit next to the reserve study and the operating budget we cover in our Back Bay market overview. Two buildings at the same price per square foot, one all-electric at 2.6 and one oil-heated at 7.1, face very different costs over the coming decades, and that difference won't appear on a listing sheet. Our Back Bay neighborhood page and buyer services cover how this fits into building-level due diligence.

FAQ

Does a building listed as "N/A until 2030" still have obligations now?

Yes. Covered buildings file whole-building energy and water data every year through ENERGY STAR Portfolio Manager and the BERDO form. They also keep supporting records for ten years and complete third-party verification on the city's schedule. The status refers only to the emissions standard.

Is a building's status final?

Not yet. The September 30 file is provisional and will be updated after the October 15 extension deadline. Buildings marked "Pending Review" will be moved to either "In Compliance" or "Action Needed."

Does the disclosure show a building's age or unit count?

No. The file has no construction-year field, and residential rows don't report unit counts. A building's compliance group is shown in the "First Emissions Compliance Year" column.

If you are weighing a Back Bay condo building, or selling in one with an "N/A until 2030" status, The Whaley Ring Team can review that building's BERDO filing alongside its budget and reserves before price is negotiated. Request a confidential market consultation.

This article is general information, not legal, tax or financial advice. Consult a qualified professional about your situation.