At a glance
Block 38, 520 WESTLAKE AVE N is a 512,665-square-foot office building in Seattle, Washington, built in 2021. In its 2025 Seattle benchmarking disclosure it reported a site energy-use intensity of 19.1 kBtu/ft² and 61 tCO₂e of greenhouse-gas emissions.
Seattle Energy Benchmarking Ordinance (SMC 22.920) · reporting year 2025
Benchmarking record
| Field | Value |
|---|---|
| ENERGY STAR score | — |
| Site EUI | 19.1 kBtu/ft² |
| Source EUI | 52.1 kBtu/ft² |
| GHG emissions | 61 tCO₂e |
| GHG intensity | 0.1 kgCO₂e/ft² |
| Electricity | 2,154,602 kWh |
| Natural gas | 3,373 therms |
| Gross floor area | 512,665 sq ft |
| Source record | seattle:50899:2025 |
The disclosure history
Year over year
| Year | Score | Δ | Site EUI | GHG emissions |
|---|---|---|---|---|
| 2025latest | — | 19.1 kBtu/ft² | 61 tCO₂e | |
| 2024 | — | 11.7 kBtu/ft² | 44 tCO₂e | |
| 2023 | — | 13.3 kBtu/ft² | 59 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.
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Location
- Address
- 520 WESTLAKE AVE N
- City
- Seattle
- State
- Washington
- ZIP
- 98109
- Coordinates
- 47.62399, -122.33804
Within ~1 km
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See also: most efficient in Seattle · biggest emitters
How does Block 38, 520 WESTLAKE AVE N 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 19.1 kBtu/ft² is about 57% 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 0.1 kgCO₂e/ft² is about 79% below the group average of 0.7 kgCO₂e/ft².
At 512,665 sq ft, it is about 161% above the average floor area of 196,452 sq ft for those buildings. It was built in 2021, 56 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 Block 38, 520 WESTLAKE AVE N's energy performance changed over time?
BuildingCensus holds 3 Seattle disclosures for Block 38, 520 WESTLAKE AVE N, covering report years 2023–2025. Site EUI moved from 13.3 kBtu/ft² (2023) to 19.1 kBtu/ft² (2025), an 44% increase. Reported emissions went from 59 tCO₂e to 61 tCO₂e over the same span (up 3%).
What does a site EUI of 19.1 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. Block 38, 520 WESTLAKE AVE N's 19.1 kBtu/ft² across 512,665 sq ft works out to about 9.8 billion Btu (2,870 MWh-equivalent) in 2025. Its source EUI of 52.1 kBtu/ft² also counts the energy lost generating and delivering that power, which is why it is higher. The disclosure also reports 2,154,602 kWh of electricity and 3,373 therms of natural gas for the year.
Which law requires Block 38, 520 WESTLAKE AVE N to report its energy use?
Block 38, 520 WESTLAKE AVE N 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:50899:2025). 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
- Interurban Exchange Iv/V & Van Vorst - Sedo· 508,160 sq ft · EUI 68.1 kBtu/ft²
- 520 Pike Building· 500,000 sq ft · score 80 (B)
- Metropolitan Park East· 497,513 sq ft · score 84 (B)
- Midtown 21 (Amazon)· 489,821 sq ft · score 95 (A)
- Amazon Brazil· 483,397 sq ft · score 96 (A)
- 1800 9th Avenue Building· 480,840 sq ft · score 99 (A)
- 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 Block 38, 520 WESTLAKE AVE N's energy grade?
Block 38, 520 WESTLAKE AVE N did not report an ENERGY STAR score in its 2025 disclosure, but its site energy-use intensity was 19.1 kBtu/ft².
How much energy does Block 38, 520 WESTLAKE AVE N use?
Its 2025 site energy-use intensity was 19.1 kBtu/ft² (52.1 kBtu/ft² source) across 512,665 sq ft, including 2,154,602 kWh of electricity and 3,373 therms of natural gas.
What are Block 38, 520 WESTLAKE AVE N's carbon emissions?
Block 38, 520 WESTLAKE AVE N reported 61 tCO₂e of greenhouse-gas emissions (0.1 kgCO₂e/ft²) for 2025.
Where is Block 38, 520 WESTLAKE AVE N?
Block 38, 520 WESTLAKE AVE N is in Seattle, Washington 98109. Its coordinates are 47.62399, -122.33804 (latitude, longitude), as published in the Building Energy Benchmarking file.
How big is Block 38, 520 WESTLAKE AVE N and when was it built?
Block 38, 520 WESTLAKE AVE N has 512,665 sq ft of gross floor area, as reported in its 2025 disclosure. The disclosure lists 2021 as its year built. It is classed as office.
Is Block 38, 520 WESTLAKE AVE N 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).
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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, “Block 38, 520 WESTLAKE AVE N, Seattle, Washington — 2025 benchmarking disclosure”, https://buildingcensus.com/buildings/seattle/block-38-e54c1abd (data as of October 2, 2026).