At a glance
505 First Avenue Building is a 443,509-square-foot office building at 505 1ST AVE S in Seattle, Washington, built in 2009. In its 2025 Seattle benchmarking disclosure it reported a site energy-use intensity of 37.7 kBtu/ft² and 76 tCO₂e of greenhouse-gas emissions.
Seattle Energy Benchmarking Ordinance (SMC 22.920) · reporting year 2025
Benchmarking record
| Field | Value |
|---|---|
| ENERGY STAR score | — |
| Site EUI | 37.7 kBtu/ft² |
| Source EUI | 104.3 kBtu/ft² |
| GHG emissions | 76 tCO₂e |
| GHG intensity | 0.3 kgCO₂e/ft² |
| Electricity | 3,324,020 kWh |
| Natural gas | 2,051 therms |
| Gross floor area | 443,509 sq ft |
| Source record | seattle:634:2025 |
The disclosure history
Year over year
| Year | Score | Δ | Site EUI | GHG emissions |
|---|---|---|---|---|
| 2025latest | — | 37.7 kBtu/ft² | 76 tCO₂e | |
| 2024 | — | 51.2 kBtu/ft² | 97 tCO₂e | |
| 2023 | — | 65.9 kBtu/ft² | 123 tCO₂e | |
| 2022 | 76 | -24 | 62.5 kBtu/ft² | 123 tCO₂e |
| 2021 | 100 | +18 | 0.4 kBtu/ft² | 132 tCO₂e |
| 2020 | 82 | +2 | 65.6 kBtu/ft² | 123 tCO₂e |
| 2019 | 80 | +1 | 77.7 kBtu/ft² | 146 tCO₂e |
| 2018 | 79 | -3 | 78.9 kBtu/ft² | 149 tCO₂e |
| 2017 | 82 | -18 | 87.1 kBtu/ft² | 150 tCO₂e |
| 2016 | 100 | +67 | 88.7 kBtu/ft² | 152 tCO₂e |
| 2015 | 33 | 99.4 kBtu/ft² | 169 tCO₂e |
Compliance context
Seattle Energy Benchmarking Ordinance (SMC 22.920)
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.
Ownership
No owning organisation shown. Names of private individuals in the disclosure are not published here.
Own or manage this building? Claim it to correct the record and get compliance alerts.
Location
- Address
- 505 1ST AVE S
- City
- Seattle
- State
- Washington
- ZIP
- 98104
- Coordinates
- 47.59767, -122.33467
Within ~1 km
Nearby benchmarked buildings
- Columbia Centerscore 90
Office · 1,952,220 sq ft
- Centurylink Field-Stadiumscore —
Stadium (Open) · 1,913,640 sq ft
- Seattle Municipal Towerscore 86
Office · 1,354,987 sq ft
- 999 Third Avescore 88
Office · 1,323,055 sq ft
- T-Mobile Park (Safeco Field)score —
Other - Entertainment/Public Assembly · 1,172,127 sq ft
- Fourth & Madison ( Idx Tower)score 81
Office · 1,052,469 sq ft
See also: most efficient in Seattle · biggest emitters
How does 505 First Avenue Building compare with other office buildings in Seattle?
The latest disclosures cover 497 office buildings in Seattle, out of 3,871 buildings citywide. Its site EUI of 37.7 kBtu/ft² is about 16% below the average of 44.8 kBtu/ft² — it uses less energy per square foot than the typical building in that group. Its emissions intensity of 0.3 kgCO₂e/ft² is about 64% below the group average of 0.7 kgCO₂e/ft².
At 443,509 sq ft, it is about 126% above the average floor area of 196,452 sq ft for those buildings. It was built in 2009, 44 years later than the group's average year built (1965). Across all 24 jurisdictions BuildingCensus covers, the 15,264 office buildings average an ENERGY STAR score of 73 and a site EUI of 59.3 kBtu/ft².
How has 505 First Avenue Building's energy performance changed over time?
BuildingCensus holds 11 Seattle disclosures for 505 First Avenue Building, covering report years 2015–2025. Its ENERGY STAR score went from 33 in 2015 to 76 in 2022 (+43 points); its best year on file was 2016, at 100. Site EUI moved from 99.4 kBtu/ft² (2015) to 37.7 kBtu/ft² (2025), a 62% decrease. Reported emissions went from 169 tCO₂e to 76 tCO₂e over the same span (down 55%).
What does a site EUI of 37.7 kBtu/ft² mean?
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. 505 First Avenue Building's 37.7 kBtu/ft² across 443,509 sq ft works out to about 16.7 billion Btu (4,900 MWh-equivalent) in 2025. Its source EUI of 104.3 kBtu/ft² also counts the energy lost generating and delivering that power, which is why it is higher. The disclosure also reports 3,324,020 kWh of electricity and 2,051 therms of natural gas for the year.
Which law requires 505 First Avenue Building to report its energy use?
505 First Avenue Building 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:634:2025). 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.
More office buildings in Seattle
- City Place Iii (Obidos/Rufus)· 438,093 sq ft · EUI 50.2 kBtu/ft²
- Hill 7 Office Bldg· 431,326 sq ft · score 91 (A)
- Urban Union (Amelia- Amazon Bldg)· 422,272 sq ft · score 90 (A)
- Metropolitan Park I (West) Office Bldg· 413,715 sq ft · EUI 27.8 kBtu/ft²
- Fifth & Yesler Bldg.· 413,264 sq ft · score 55 (C)
- Parkview & Waterside Campus· 404,916 sq ft · EUI 70.5 kBtu/ft²
- Office buildings in Seattle· 497 benchmarked
- All Seattle benchmarked buildings· Seattle Energy Benchmarking Ordinance (SMC 22.920)
- Most efficient large buildings in Seattle
- Least efficient large buildings in Seattle
- Biggest emitters in Seattle
Frequently asked questions
What is 505 First Avenue Building's energy grade?
505 First Avenue Building did not report an ENERGY STAR score in its 2025 disclosure, but its site energy-use intensity was 37.7 kBtu/ft².
How much energy does 505 First Avenue Building use?
Its 2025 site energy-use intensity was 37.7 kBtu/ft² (104.3 kBtu/ft² source) across 443,509 sq ft, including 3,324,020 kWh of electricity and 2,051 therms of natural gas.
What are 505 First Avenue Building's carbon emissions?
505 First Avenue Building reported 76 tCO₂e of greenhouse-gas emissions (0.3 kgCO₂e/ft²) for 2025.
Where is 505 First Avenue Building?
505 First Avenue Building is at 505 1ST AVE S, in Seattle, Washington 98104. Its coordinates are 47.59767, -122.33467 (latitude, longitude), as published in the Building Energy Benchmarking file.
How big is 505 First Avenue Building and when was it built?
505 First Avenue Building has 443,509 sq ft of gross floor area, as reported in its 2025 disclosure. The disclosure lists 2009 as its year built. It is classed as office.
Is 505 First Avenue Building covered by the Seattle Energy Benchmarking Ordinance (SMC 22.920)?
Yes — it appears in the 2025 Building Energy Benchmarking disclosure, which lists the buildings reporting under the Seattle Energy Benchmarking Ordinance (SMC 22.920).
Working with Seattle building benchmarking records? Pro adds alerts, change history and CSV export ($49/mo); Enterprise adds full national files, the API and an MCP server for AI tools.
About this data
Source: Building Energy Benchmarking (Seattle Energy Benchmarking Ordinance (SMC 22.920)), as published October 2, 2026. See the methodology for how records are matched, cleaned and scored.
Cite as: BuildingCensus, “505 First Avenue Building, Seattle, Washington — 2025 benchmarking disclosure”, https://buildingcensus.com/buildings/seattle/505-first-avenue-building-c1d1167a (data as of October 2, 2026).