21 Walden Square Road
Multifamily Housing in Cambridge, MA
At a glance
21 Walden Square Road is a 250,389-square-foot multifamily housing building in Cambridge, Massachusetts, built in 1974. In its 2024 Cambridge benchmarking disclosure it reported an ENERGY STAR score of 86 out of 100 (grade A), a site energy-use intensity of 77.2 kBtu/ft² and 1,093 tCO₂e of greenhouse-gas emissions. That score is higher than 52% of the 155 scored multifamily housing buildings in Cambridge.
BEUDO · reporting year 2024
Benchmarking record
| Field | Value |
|---|---|
| ENERGY STAR score | 86 (band A) |
| Site EUI | 77.2 kBtu/ft² |
| Source EUI | 105.2 kBtu/ft² |
| GHG emissions | 1,093 tCO₂e |
| GHG intensity | — |
| Electricity | 1,013,569 kWh |
| Natural gas | 158,733 therms |
| Water use | 10,723 kgal |
| Gross floor area | 250,389 sq ft |
| Source record | cambridge:B1642:2024 |
The disclosure history
Year over year
| Year | Score | Δ | Site EUI | GHG emissions |
|---|---|---|---|---|
| 2024latest | 86 | -3 | 77.2 kBtu/ft² | 1,093 tCO₂e |
| 2023 | 89 | -2 | 73.3 kBtu/ft² | 1,038 tCO₂e |
| 2022 | 91 | -8 | 72.7 kBtu/ft² | 1,029 tCO₂e |
| 2021 | 99 | +14 | 59.7 kBtu/ft² | 823 tCO₂e |
| 2020 | 85 | -1 | 81.1 kBtu/ft² | 1,136 tCO₂e |
| 2019 | 86 | -6 | 82.5 kBtu/ft² | 1,136 tCO₂e |
| 2018 | 92 | ±0 | 72.6 kBtu/ft² | 1,023 tCO₂e |
| 2017 | 92 | +2 | 70.5 kBtu/ft² | 1,009 tCO₂e |
| 2016 | 90 | +8 | 72.8 kBtu/ft² | 1,043 tCO₂e |
| 2015 | 82 | 86.0 kBtu/ft² | 1,224 tCO₂e |
Compliance context
BEUDO
Cambridge's 2023 BEUDO amendments require non-residential buildings of 100,000+ sq ft to reach net-zero emissions by 2035 (reductions starting 2026) and those of 25,000–100,000 sq ft by 2050 (starting 2030).
Ownership
WSQ LIMITED PARTNERSHIP
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Location
- Address
- 21 Walden Square Road
- City
- Cambridge
- State
- Massachusetts
- Coordinates
- 42.38910, -71.13060
Within ~1 km
Nearby benchmarked buildings
- 46-56 Linnaean Streetscore —
Residence Hall/Dormitory · 251,014 sq ft
- 362 Rindge Avescore 57
Multifamily Housing · 249,723 sq ft
- 205-225 Walden St.score 89
Multifamily Housing · 229,040 sq ft
- 1 Jackson Placescore 88
Multifamily Housing · 207,765 sq ft
- 1 Jackson Placescore 73
Multifamily Housing · 207,765 sq ft
- 64 Linnaean Streetscore —
Residence Hall/Dormitory · 191,944 sq ft
See also: most efficient in Cambridge · biggest emitters
How does 21 Walden Square Road compare with other multifamily housing buildings in Cambridge?
The latest disclosures cover 187 multifamily housing buildings in Cambridge, out of 902 buildings citywide. 21 Walden Square Road's ENERGY STAR score of 86 compares with an average of 75 across the 155 that report a score; it scores higher than 52% of them and lower than 46%. Its site EUI of 77.2 kBtu/ft² is about 36% above the average of 56.9 kBtu/ft² — it uses more energy per square foot than the typical building in that group.
At 250,389 sq ft, it is about 89% above the average floor area of 132,415 sq ft for those buildings. Its 1974 construction date is close to the group's average year built (1973). Across all 24 jurisdictions BuildingCensus covers, the 59,945 multifamily housing buildings average an ENERGY STAR score of 70 and a site EUI of 59.0 kBtu/ft².
How has 21 Walden Square Road's energy performance changed over time?
BuildingCensus holds 10 Cambridge disclosures for 21 Walden Square Road, covering report years 2015–2024. Its ENERGY STAR score went from 82 in 2015 to 86 in 2024 (+4 points); its best year on file was 2021, at 99. Site EUI moved from 86.0 kBtu/ft² (2015) to 77.2 kBtu/ft² (2024), a 10% decrease. Reported emissions went from 1,224 tCO₂e to 1,093 tCO₂e over the same span (down 11%).
What does an ENERGY STAR score of 86 mean?
ENERGY STAR scores run from 1 to 100 and are computed by the EPA's Portfolio Manager as a percentile against similar buildings nationwide, adjusted for climate, size and use: a score of 86 means the building performs better than about 86% of its national peers. BuildingCensus bands the score into report-card grades; 86 falls in band A — high performer (85–100). Scores of 75 or higher meet the threshold for ENERGY STAR certification; certification itself is a separate, verified application that the disclosure does not record. In Cambridge, 50% of scored buildings are at 75 or above.
Site energy-use intensity (EUI) is the energy a building uses on site in a year divided by its floor area, in thousand Btu per square foot — lower is more efficient. 21 Walden Square Road's 77.2 kBtu/ft² across 250,389 sq ft works out to about 19.3 billion Btu (5,665 MWh-equivalent) in 2024. Its source EUI of 105.2 kBtu/ft² also counts the energy lost generating and delivering that power, which is why it is higher. The disclosure also reports 1,013,569 kWh of electricity, 158,733 therms of natural gas and 10,723 thousand gallons of water for the year.
Which law requires 21 Walden Square Road to report its energy use?
21 Walden Square Road reports under BEUDO, the legal basis of Cambridge's Building Energy Use Disclosure Ordinance (BEUDO), which publishes each covered building's annual benchmarking results. The record shown here is the report-year 2024 disclosure (source record cambridge:B1642:2024). Cambridge's 2023 BEUDO amendments require non-residential buildings of 100,000+ sq ft to reach net-zero emissions by 2035 (reductions starting 2026) and those of 25,000–100,000 sq ft by 2050 (starting 2030).
More multifamily housing buildings in Cambridge
- 362 Rindge Ave· 249,723 sq ft · score 57 (C)
- 364 Rindge Ave· 249,723 sq ft · score 46 (D)
- 129 Franklin Street· 243,166 sq ft · score 98 (A)
- 100 Landsdowne Street· 239,086 sq ft · score 43 (D)
- 205-225 Walden St.· 229,040 sq ft · score 89 (A)
- 80 Cambridgepark Drive· 225,358 sq ft · score 96 (A)
- Multifamily Housing buildings in Cambridge· 187 benchmarked
- All Cambridge benchmarked buildings· BEUDO
- Most efficient large buildings in Cambridge
- Least efficient large buildings in Cambridge
- Biggest emitters in Cambridge
Frequently asked questions
What is 21 Walden Square Road's energy grade?
21 Walden Square Road scores 86 out of 100 on ENERGY STAR — band A, high performer (85–100) — in its 2024 Cambridge disclosure. Scores are national percentiles against similar buildings; 75+ qualifies for ENERGY STAR certification.
How much energy does 21 Walden Square Road use?
Its 2024 site energy-use intensity was 77.2 kBtu/ft² (105.2 kBtu/ft² source) across 250,389 sq ft, including 1,013,569 kWh of electricity and 158,733 therms of natural gas.
What are 21 Walden Square Road's carbon emissions?
21 Walden Square Road reported 1,093 tCO₂e of greenhouse-gas emissions for 2024.
Where is 21 Walden Square Road?
21 Walden Square Road is in Cambridge, Massachusetts. Its coordinates are 42.38910, -71.13060 (latitude, longitude), as published in the Building Energy Use Disclosure Ordinance (BEUDO) file.
How big is 21 Walden Square Road and when was it built?
21 Walden Square Road has 250,389 sq ft of gross floor area, as reported in its 2024 disclosure. The disclosure lists 1974 as its year built. It is classed as multifamily housing.
Is 21 Walden Square Road covered by BEUDO?
Yes — it appears in the 2024 Building Energy Use Disclosure Ordinance (BEUDO) disclosure, which lists the buildings reporting under BEUDO.
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About this data
Source: Building Energy Use Disclosure Ordinance (BEUDO) (BEUDO), as published October 2, 2026. See the methodology for how records are matched, cleaned and scored.
Cite as: BuildingCensus, “21 Walden Square Road, Cambridge, Massachusetts — 2024 benchmarking disclosure”, https://buildingcensus.com/buildings/cambridge/21-walden-square-road-73bd50d4 (data as of October 2, 2026).