635 E 21st St

How does 635 E 21st St compare with other multifamily housing buildings in New York City?

The latest disclosures cover 33,022 multifamily housing buildings in New York City, out of 48,310 buildings citywide. 635 E 21st St's ENERGY STAR score of 41 compares with an average of 63 across the 22,829 that report a score; it scores higher than 25% of them and lower than 75%. Its site EUI of 86.1 kBtu/ft² is about 15% above the average of 74.9 kBtu/ft² — it uses more energy per square foot than the typical building in that group. Its emissions intensity of 5.2 kgCO₂e/ft² is roughly in line with the group average of 5.2 kgCO₂e/ft².

At 38,800 sq ft, it is about 62% below the average floor area of 100,951 sq ft for those buildings. It was built in 1935, 17 years earlier than the group's average year built (1952). 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 635 E 21st St's energy performance changed over time?

BuildingCensus holds 3 New York City disclosures for 635 E 21st St, covering report years 2022–2024. Its ENERGY STAR score went from 38 in 2022 to 41 in 2024 (+3 points); its best year on file was 2023, at 42. Site EUI moved from 91.6 kBtu/ft² (2022) to 86.1 kBtu/ft² (2024), a 6% decrease. Reported emissions went from 204 tCO₂e to 203 tCO₂e over the same span (down 0%).

What does an ENERGY STAR score of 41 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 41 means the building performs better than about 41% of its national peers. BuildingCensus bands the score into report-card grades; 41 falls in band D — lowest band (1–54). It sits 34 points below 75, the threshold for ENERGY STAR certification. In New York City, 43% 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. 635 E 21st St's 86.1 kBtu/ft² across 38,800 sq ft works out to about 3.3 billion Btu (979 MWh-equivalent) in 2024. Its source EUI of 109.1 kBtu/ft² also counts the energy lost generating and delivering that power, which is why it is higher. The disclosure also reports 120,950 kWh of electricity, 29,299 therms of natural gas and 2,392 thousand gallons of water for the year.

Which law requires 635 E 21st St to report its energy use?

635 E 21st St reports under Local Law 84 (LL84), the legal basis of New York City's Energy and Water Data Disclosure program, which publishes each covered building's annual benchmarking results. The record shown here is the report-year 2024 disclosure (source record nyc:6654620:2024). Under Local Law 97, buildings over 25,000 sq ft face carbon caps with fines of $268 per metric ton of CO₂e over the limit, phasing in from 2024.