At a glance
Century Square is a 755,000-square-foot office building at 1501 4TH AVE in Seattle, Washington, built in 1985. In its 2025 Seattle benchmarking disclosure it reported an ENERGY STAR score of 83 out of 100 (grade B), a site energy-use intensity of 46.0 kBtu/ft² and 498 tCO₂e of greenhouse-gas emissions. That score is higher than 49% of the 378 scored office buildings in Seattle.
Seattle Energy Benchmarking Ordinance (SMC 22.920) · reporting year 2025
Benchmarking record
| Field | Value |
|---|---|
| ENERGY STAR score | 83 (band B) |
| Site EUI | 46.0 kBtu/ft² |
| Source EUI | 112.3 kBtu/ft² |
| GHG emissions | 498 tCO₂e |
| GHG intensity | 0.7 kgCO₂e/ft² |
| Electricity | 7,162,155 kWh |
| Natural gas | 57,158 therms |
| Gross floor area | 755,000 sq ft |
| Source record | seattle:415:2025 |
The disclosure history
Year over year
| Year | Score | Δ | Site EUI | GHG emissions |
|---|---|---|---|---|
| 2025latest | 83 | +6 | 46.0 kBtu/ft² | 498 tCO₂e |
| 2024 | 77 | +9 | 54.1 kBtu/ft² | 647 tCO₂e |
| 2023 | 68 | -1 | 60.7 kBtu/ft² | 623 tCO₂e |
| 2022 | 69 | ±0 | 62.3 kBtu/ft² | 682 tCO₂e |
| 2021 | 69 | -5 | 59.4 kBtu/ft² | 560 tCO₂e |
| 2020 | 74 | +5 | 56.8 kBtu/ft² | 497 tCO₂e |
| 2019 | 69 | +4 | 73.0 kBtu/ft² | 734 tCO₂e |
| 2018 | 65 | +9 | 77.0 kBtu/ft² | 729 tCO₂e |
| 2017 | 56 | -16 | 80.3 kBtu/ft² | 720 tCO₂e |
| 2016 | 72 | +5 | 78.1 kBtu/ft² | 744 tCO₂e |
| 2015 | 67 | 88.4 kBtu/ft² | 1,192 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
- 1501 4TH AVE
- City
- Seattle
- State
- Washington
- ZIP
- 98101
- Coordinates
- 47.61022, -122.33745
Within ~1 km
Nearby benchmarked buildings
- Columbia Centerscore 90
Office · 1,952,220 sq ft
- Seattle Convention Centerscore —
Convention Center · 1,842,925 sq ft
- Two Union Squarescore 96
Office · 1,605,578 sq ft
Office · 1,599,394 sq ft
- Day 1 Tower And Spheres (Amazon)score 93
Office · 1,599,230 sq ft
- Russell Investments Centerscore 92
Office · 1,592,914 sq ft
See also: most efficient in Seattle · biggest emitters
How does Century Square compare with other office buildings in Seattle?
The latest disclosures cover 497 office buildings in Seattle, out of 3,871 buildings citywide. Century Square's ENERGY STAR score of 83 compares with an average of 76 across the 378 that report a score; it scores higher than 49% of them and lower than 49%. Its site EUI of 46.0 kBtu/ft² is roughly in line with the average of 44.8 kBtu/ft². Its emissions intensity of 0.7 kgCO₂e/ft² is roughly in line with the group average of 0.7 kgCO₂e/ft².
At 755,000 sq ft, it is about 284% above the average floor area of 196,452 sq ft for those buildings. It was built in 1985, 20 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 Century Square's energy performance changed over time?
BuildingCensus holds 11 Seattle disclosures for Century Square, covering report years 2015–2025. Its ENERGY STAR score went from 67 in 2015 to 83 in 2025 (+16 points). Site EUI moved from 88.4 kBtu/ft² (2015) to 46.0 kBtu/ft² (2025), a 48% decrease. Reported emissions went from 1,192 tCO₂e to 498 tCO₂e over the same span (down 58%).
What does an ENERGY STAR score of 83 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 83 means the building performs better than about 83% of its national peers. BuildingCensus bands the score into report-card grades; 83 falls in band B — above median (70–84). 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. Century Square's 46.0 kBtu/ft² across 755,000 sq ft works out to about 34.7 billion Btu (10,178 MWh-equivalent) in 2025. Its source EUI of 112.3 kBtu/ft² also counts the energy lost generating and delivering that power, which is why it is higher. The disclosure also reports 7,162,155 kWh of electricity and 57,158 therms of natural gas for the year.
Which law requires Century Square to report its energy use?
Century Square 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:415:2025). 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
- 1700 Seventh Building· 747,747 sq ft · EUI 35.8 kBtu/ft²
- 901 Fifth Avenue· 711,611 sq ft · score 78 (B)
- 2nd & Seneca Blds· 635,303 sq ft · score 95 (A)
- Block 31 - Google· 614,956 sq ft · score 89 (A)
- Amazon Phase Vi - Nessie And Bigfoot· 593,200 sq ft · score 95 (A)
- 1000 2nd Avenue Building· 589,921 sq ft · score 84 (B)
- 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 Century Square's energy grade?
Century Square scores 83 out of 100 on ENERGY STAR — band B, above median (70–84) — in its 2025 Seattle disclosure. Scores are national percentiles against similar buildings; 75+ qualifies for ENERGY STAR certification.
How much energy does Century Square use?
Its 2025 site energy-use intensity was 46.0 kBtu/ft² (112.3 kBtu/ft² source) across 755,000 sq ft, including 7,162,155 kWh of electricity and 57,158 therms of natural gas.
What are Century Square's carbon emissions?
Century Square reported 498 tCO₂e of greenhouse-gas emissions (0.7 kgCO₂e/ft²) for 2025.
Where is Century Square?
Century Square is at 1501 4TH AVE, in Seattle, Washington 98101. Its coordinates are 47.61022, -122.33745 (latitude, longitude), as published in the Building Energy Benchmarking file.
How big is Century Square and when was it built?
Century Square has 755,000 sq ft of gross floor area, as reported in its 2025 disclosure. The disclosure lists 1985 as its year built. It is classed as office.
Is Century Square 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, “Century Square, Seattle, Washington — 2025 benchmarking disclosure”, https://buildingcensus.com/buildings/seattle/century-square-3e6f6385 (data as of October 2, 2026).