Fifteen Twenty-One Second Avenue

How does Fifteen Twenty-One Second Avenue compare with other multifamily housing buildings in Seattle?

The latest disclosures cover 1,971 multifamily housing buildings in Seattle, out of 3,871 buildings citywide. Fifteen Twenty-One Second Avenue's ENERGY STAR score of 31 compares with an average of 83 across the 1,652 that report a score; it scores higher than 3% of them and lower than 96%. Its site EUI of 59.5 kBtu/ft² is about 70% above the average of 34.9 kBtu/ft² — it uses more energy per square foot than the typical building in that group. Its emissions intensity of 1.9 kgCO₂e/ft² is about 171% above the group average of 0.7 kgCO₂e/ft².

At 330,693 sq ft, it is about 282% above the average floor area of 86,468 sq ft for those buildings. It was built in 2008, 25 years later than the group's average year built (1983). 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 Fifteen Twenty-One Second Avenue's energy performance changed over time?

BuildingCensus holds 11 Seattle disclosures for Fifteen Twenty-One Second Avenue, covering report years 2015–2025. Its ENERGY STAR score went from 48 in 2015 to 31 in 2025 (-17 points); its best year on file was 2019, at 62. Site EUI moved from 60.1 kBtu/ft² (2015) to 59.5 kBtu/ft² (2025), a 1% decrease. Reported emissions went from 590 tCO₂e to 628 tCO₂e over the same span (up 7%).

What does an ENERGY STAR score of 31 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 31 means the building performs better than about 31% of its national peers. BuildingCensus bands the score into report-card grades; 31 falls in band D — lowest band (1–54). It sits 44 points below 75, the threshold for ENERGY STAR certification. In Seattle, 69% 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. Fifteen Twenty-One Second Avenue's 59.5 kBtu/ft² across 330,693 sq ft works out to about 19.7 billion Btu (5,767 MWh-equivalent) in 2025. Its source EUI of 107.8 kBtu/ft² also counts the energy lost generating and delivering that power, which is why it is higher. The disclosure also reports 2,511,540 kWh of electricity and 110,750 therms of natural gas for the year.

Which law requires Fifteen Twenty-One Second Avenue to report its energy use?

Fifteen Twenty-One Second Avenue reports under the Seattle Energy Benchmarking Ordinance (SMC 22.920), the legal basis of Seattle's Building Energy Benchmarking program, which publishes each covered building's annual benchmarking results. The record shown here is the report-year 2025 disclosure (source record seattle:21776:2025). Seattle's Building Emissions Performance Standard (adopted 2023) applies to buildings over 20,000 sq ft: benchmarking verification is due 2027–2030 and initial emissions targets 2031–2035, reaching net zero by 2041–2050, with fines for non-compliance.