Alley 24 (North & South Tower)

How does Alley 24 (North & South Tower) 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. Alley 24 (North & South Tower)'s ENERGY STAR score of 92 compares with an average of 83 across the 1,652 that report a score; it scores higher than 52% of them and lower than 45%. Its site EUI of 36.0 kBtu/ft² is roughly in line with the average of 34.9 kBtu/ft². Its emissions intensity of 0.8 kgCO₂e/ft² is about 10% above the group average of 0.7 kgCO₂e/ft².

At 171,874 sq ft, it is about twice the average floor area of 86,468 sq ft for those buildings. It was built in 2006, 23 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 Alley 24 (North & South Tower)'s energy performance changed over time?

BuildingCensus holds 11 Seattle disclosures for Alley 24 (North & South Tower), covering report years 2015–2025. Its ENERGY STAR score went from 76 in 2016 to 92 in 2025 (+16 points); its best year on file was 2024, at 95. Site EUI moved from 34.3 kBtu/ft² (2015) to 36.0 kBtu/ft² (2025), an 5% increase. Reported emissions went from 149 tCO₂e to 101 tCO₂e over the same span (down 32%).

What does an ENERGY STAR score of 92 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 92 means the building performs better than about 92% of its national peers. BuildingCensus bands the score into report-card grades; 92 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 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. Alley 24 (North & South Tower)'s 36.0 kBtu/ft² across 171,874 sq ft works out to about 6.2 billion Btu (1,813 MWh-equivalent) in 2025. Its source EUI of 79.7 kBtu/ft² also counts the energy lost generating and delivering that power, which is why it is higher. The disclosure also reports 921,553 kWh of electricity and 15,904 therms of natural gas for the year.

Which law requires Alley 24 (North & South Tower) to report its energy use?

Alley 24 (North & South Tower) 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:26188:2025). 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.