BuildingCensus
C

Homborness Condominium

Multifamily Housing in Seattle, WA · 321 BOYLSTON AVE E · 98102

At a glance

Homborness Condominium is a 20,832-square-foot multifamily housing building at 321 BOYLSTON AVE E in Seattle, Washington, built in 1925. In its 2025 Seattle benchmarking disclosure it reported an ENERGY STAR score of 63 out of 100 (grade C), a site energy-use intensity of 58.7 kBtu/ft² and 59 tCO₂e of greenhouse-gas emissions. That score is higher than 14% of the 1,652 scored multifamily housing buildings in Seattle.

ENERGY STAR score
63
band C · 2025
Site EUI
58.7
kBtu/ft²
GHG emissions
59
tCO₂e
GHG intensity
2.4
kgCO₂e/ft²
Floor area
20,832
sq ft
Year built
1925
vintage
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85–10070–8455–691–54
This entry + 6 nearby

Seattle Energy Benchmarking Ordinance (SMC 22.920) · reporting year 2025

Benchmarking record

FieldValue
ENERGY STAR score63 (band C)
Site EUI58.7 kBtu/ft²
Source EUI85.5 kBtu/ft²
GHG emissions59 tCO₂e
GHG intensity2.4 kgCO₂e/ft²
Electricity97,398 kWh
Natural gas10,961 therms
Gross floor area20,832 sq ft
Source recordseattle:24156:2025

The disclosure history

Year over year

YearScoreΔSite EUIGHG emissions
2025latest63+1758.7 kBtu/ft²59 tCO₂e
202446-1465.2 kBtu/ft²67 tCO₂e
20236062.4 kBtu/ft²66 tCO₂e
2022——2 tCO₂e
2021———
202051+282.8 kBtu/ft²78 tCO₂e
201949+385.9 kBtu/ft²82 tCO₂e
201846-186.8 kBtu/ft²83 tCO₂e
201747+1391.4 kBtu/ft²86 tCO₂e
201634+278.4 kBtu/ft²71 tCO₂e
20153278.9 kBtu/ft²71 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.

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Ownership

No owning organisation shown. Names of private individuals in the disclosure are not published here.

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Location

Address
321 BOYLSTON AVE E
State
Washington
ZIP
98102
Coordinates
47.62177, -122.32338

Within ~1 km

Nearby benchmarked buildings

See also: most efficient in Seattle · biggest emitters

How does Homborness Condominium 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. Homborness Condominium's ENERGY STAR score of 63 compares with an average of 83 across the 1,652 that report a score; it scores higher than 14% of them and lower than 86%. Its site EUI of 58.7 kBtu/ft² is about 68% above the average of 34.9 kBtu/ft² — it uses more energy per square foot than the typical building in that group. Its emissions intensity of 2.4 kgCO₂e/ft² is about 247% above the group average of 0.7 kgCO₂e/ft².

At 20,832 sq ft, it is about 76% below the average floor area of 86,468 sq ft for those buildings. It was built in 1925, 58 years earlier 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 Homborness Condominium's energy performance changed over time?

BuildingCensus holds 11 Seattle disclosures for Homborness Condominium, covering report years 2015–2025. Its ENERGY STAR score went from 32 in 2015 to 63 in 2025 (+31 points). Site EUI moved from 78.9 kBtu/ft² (2015) to 58.7 kBtu/ft² (2025), a 26% decrease. Reported emissions went from 71 tCO₂e to 59 tCO₂e over the same span (down 16%).

What does an ENERGY STAR score of 63 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 63 means the building performs better than about 63% of its national peers. BuildingCensus bands the score into report-card grades; 63 falls in band C — below median (55–69). It sits 12 points below 75, the threshold for ENERGY STAR certification. 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. Homborness Condominium's 58.7 kBtu/ft² across 20,832 sq ft works out to about 1.2 billion Btu (358 MWh-equivalent) in 2025. Its source EUI of 85.5 kBtu/ft² also counts the energy lost generating and delivering that power, which is why it is higher. The disclosure also reports 97,398 kWh of electricity and 10,961 therms of natural gas for the year.

Which law requires Homborness Condominium to report its energy use?

Homborness Condominium 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:24156:2025). 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 multifamily housing buildings in Seattle

Frequently asked questions

What is Homborness Condominium's energy grade?

Homborness Condominium scores 63 out of 100 on ENERGY STAR — band C, below median (55–69) — in its 2025 Seattle disclosure. Scores are national percentiles against similar buildings; 75+ qualifies for ENERGY STAR certification.

How much energy does Homborness Condominium use?

Its 2025 site energy-use intensity was 58.7 kBtu/ft² (85.5 kBtu/ft² source) across 20,832 sq ft, including 97,398 kWh of electricity and 10,961 therms of natural gas.

What are Homborness Condominium's carbon emissions?

Homborness Condominium reported 59 tCO₂e of greenhouse-gas emissions (2.4 kgCO₂e/ft²) for 2025.

Where is Homborness Condominium?

Homborness Condominium is at 321 BOYLSTON AVE E, in Seattle, Washington 98102. Its coordinates are 47.62177, -122.32338 (latitude, longitude), as published in the Building Energy Benchmarking file.

How big is Homborness Condominium and when was it built?

Homborness Condominium has 20,832 sq ft of gross floor area, as reported in its 2025 disclosure. The disclosure lists 1925 as its year built. It is classed as multifamily housing.

Is Homborness Condominium 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, “Homborness Condominium, Seattle, Washington — 2025 benchmarking disclosure”, https://buildingcensus.com/buildings/seattle/homborness-condominium-66c829ad (data as of October 2, 2026).