Portage Bay Apts

How does Portage Bay Apts 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. Portage Bay Apts's ENERGY STAR score of 95 compares with an average of 83 across the 1,652 that report a score; it scores higher than 61% of them and lower than 35%. Its site EUI of 28.5 kBtu/ft² is about 18% below the average of 34.9 kBtu/ft² — it uses less energy per square foot than the typical building in that group. Its emissions intensity of 0.2 kgCO₂e/ft² is about 77% below the group average of 0.7 kgCO₂e/ft².

At 46,689 sq ft, it is about half of the average floor area of 86,468 sq ft for those buildings. It was built in 1986, 3 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 Portage Bay Apts's energy performance changed over time?

BuildingCensus holds 11 Seattle disclosures for Portage Bay Apts, covering report years 2015–2025. Its ENERGY STAR score was 95 in both 2015 and 2025. Site EUI moved from 26.3 kBtu/ft² (2015) to 28.5 kBtu/ft² (2025), an 8% increase. Reported emissions went from 6 tCO₂e to 6 tCO₂e over the same span (up 7%).

What does an ENERGY STAR score of 95 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 95 means the building performs better than about 95% of its national peers. BuildingCensus bands the score into report-card grades; 95 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. Portage Bay Apts's 28.5 kBtu/ft² across 46,689 sq ft works out to about 1.3 billion Btu (390 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 305,349 kWh of electricity for the year.

Which law requires Portage Bay Apts to report its energy use?

Portage Bay Apts 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:25696:2025). 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.