Climate Action & Building Decarbonization in Seattle#

Seattle has set ambitious targets to reduce greenhouse gas emissions, with building energy and transportation accounting for nearly all of the city’s climate pollution. This guide covers the city’s climate policies, building decarbonization programs, transportation emissions strategies, and how land use decisions shape Seattle’s climate future.

Current policies and programs#

Seattle’s climate work is organized around three main emission sources: buildings (approximately 40% of emissions), transportation (approximately 60%), and waste. The Office of Sustainability & Environment (OSE) leads citywide climate policy, while programs span multiple departments. (Seattle OSE: Climate Change)

Building Emissions Performance Standard (BEPS)#

Seattle’s Building Emissions Performance Standard, signed into law by Mayor Harrell in December 2023, requires nonresidential and multifamily buildings over 20,000 square feet to progressively reduce greenhouse gas emissions and reach net-zero emissions between 2041 and 2050. Buildings must verify emissions data and submit greenhouse gas reports by 2027-2030, then meet initial emissions targets by 2031-2035. The policy is projected to reduce building sector emissions by 27% by 2050. (Seattle OSE: BEPS | The Urbanist: Harrell Signs BEPS Into Law)

Energy benchmarking#

Since 2010, Seattle has required owners of nonresidential and multifamily buildings over 20,000 square feet to track energy performance and report annually to the city under Seattle Municipal Code Chapter 22.920. The program covers more than 3,700 buildings representing over 330 million square feet. Building energy data is published publicly to increase market transparency and drive efficiency improvements. (Seattle OSE: Energy Benchmarking)

Building tune-ups#

The Building Tune-Ups program requires large buildings to undergo operational assessments that identify low-cost energy and water efficiency improvements, typically yielding 10-15% energy savings. Compliance deadlines are staggered by building size: 200,000+ square feet by October 2023, 100,000-199,999 square feet by October 2024, 70,000-99,999 square feet by October 2025, and 50,000-69,999 square feet by October 2026. (Seattle OSE: Building Tune-Ups)

Building electrification and the Seattle Energy Code#

Seattle’s Energy Code is updated every three years and sets efficiency standards for new commercial and multifamily construction. The code has progressively moved toward electrification by requiring more efficient heating and cooling systems. Over 90% of building emissions come from fossil fuel combustion for heating and appliances, making the transition from natural gas to electric heat pumps a central strategy. (Seattle OSE: Buildings & Energy)

The Clean Heat Program helps households switch from oil heating to energy-efficient heat pumps. Since 2017, the program has helped more than 2,000 households convert, and the city is on track to eliminate heating oil use by 2030. (Seattle OSE: Buildings & Energy)

State-level electrification policy has been contested. In November 2024, voters passed Initiative 2066 (51.7% Yes), an industry-backed measure intended to block restrictions on natural gas service. On March 21, 2025, King County Superior Court ruled I-2066 unconstitutional on single-subject grounds; the case is now before the Washington Supreme Court. (Ballotpedia: I-2066)

Transportation emissions#

Transportation is Seattle’s largest source of greenhouse gas emissions, responsible for approximately 60% of the city’s climate pollution. The city’s approach centers on reducing vehicle miles traveled through land use, expanding transit and active transportation, and electrifying remaining vehicles. (Seattle OSE: Transportation Emissions)

Seattle’s Climate Change Response Framework (2023) set a target of increasing transit mode share from 11% to 24% of all trips by 2030 — requiring a transformation of how residents move through the city. (The Urbanist: 2030 Mode Shift Goals)

The Transportation Electrification Blueprint (2021) sets goals for electrifying the city’s vehicle fleet and supporting private EV adoption, including a target of 100% fossil-fuel-free city fleet by 2030. (Seattle OSE: Transportation Electrification Blueprint)

The Low Pollution Neighborhoods initiative, launched by mayoral executive order in December 2022, targets emissions reductions in communities most burdened by traffic pollution, with candidate neighborhoods including Georgetown, South Park, and Beacon Hill. (SDOT: Low Pollution Neighborhoods | The Urbanist: Low Pollution Neighborhood Pledge)

Green New Deal#

Seattle’s Green New Deal, established through Resolution 31895 (2019) and Executive Order 2020-01, is the city’s overarching climate justice framework. Funded in part by the JumpStart Payroll Expense Tax, it focuses on three pillars: addressing climate and environmental injustice, promoting healthy communities, and investing in an inclusive green economy. (Seattle OSE: Green New Deal)

The Green New Deal Oversight Board provides community oversight and policy recommendations to ensure implementation centers communities of color and frontline neighborhoods. (Seattle OSE: Green New Deal)

Urban heat island#

A 2020 Seattle/King County heat mapping study found significant temperature disparities across the city, with formerly redlined neighborhoods and areas with less tree canopy experiencing the highest temperatures. According to Climate Central, more than 80% of Seattle’s population lives on heat islands, and 54% live in areas that are at least 8°F warmer than surrounding areas. Capitol Hill averages 2.4°F above the citywide average, while neighborhoods with more tree canopy like Madison Park are cooler. (Seattle Trees: Urban Heat | Axios Seattle: Heat Islands)

The city uses heat mapping data to prioritize tree planting and cooling infrastructure in the most heat-vulnerable neighborhoods, connecting climate adaptation to the broader Parks, Open Space & Urban Tree Canopy work.

History#

2005: U.S. Mayors Climate Protection Agreement#

Seattle Mayor Greg Nickels launched the U.S. Conference of Mayors Climate Protection Agreement on February 16, 2005 — the day the Kyoto Protocol took effect internationally — pledging that Seattle would meet the Protocol’s emission reduction targets. Over 1,000 mayors eventually signed the agreement. (U.S. Conference of Mayors: Climate Protection Center | Harvard IOP: Greg Nickels)

2013: Climate Action Plan#

Seattle adopted its Climate Action Plan (CAP), setting a target to reduce greenhouse gas emissions 58% below 2008 levels by 2030 and achieve net-zero core emissions by 2050. The plan established sector-specific targets: 82% reduction from passenger vehicles and 39% from building energy by 2030, organized across 148 specific actions in transportation, building energy, waste, and climate preparedness. (Seattle OSE: Climate Action Plan (PDF))

2019: Green New Deal resolution#

The Seattle City Council passed Resolution 31895, establishing the Green New Deal framework with a goal of achieving a “just transition” to a green economy. The resolution committed the city to centering environmental justice and created the Oversight Board. Mayor Durkan followed with Executive Order 2020-01, directing departments to implement Green New Deal strategies. (Seattle OSE: Green New Deal)

2020: Heat island mapping#

Seattle Utilities partnered with King County and OSE to create a Heat Watch Map documenting air temperature variations across the city during extreme heat events. The study revealed that urban heat impacts are distributed inequitably, with hotter conditions concentrated in areas with less tree canopy, more impervious surfaces, and historically disinvested communities. (Seattle Trees: Urban Heat)

2023: BEPS enacted#

The Seattle City Council unanimously passed the Building Emissions Performance Standard on December 12, 2023, and Mayor Harrell signed it into law the following day. The law makes Seattle one of the first cities in the nation to require large existing buildings to meet greenhouse gas performance targets on a path to net-zero. OSE published the final Director’s Rule on December 9, 2025, establishing the compliance framework with reporting obligations starting October 1, 2027. (Seattle City Council: BEPS Passage | Seattle OSE: BEPS Rulemaking)

2024: Climate Commitment Act preserved; Buy Clean Buy Fair enacted#

In November 2024, Washington voters rejected Initiative 2117 (61.95% No), preserving the state’s Climate Commitment Act cap-and-invest program that funds many Seattle climate programs. (Ballotpedia: I-2117) In March 2024, Governor Inslee signed the Buy Clean Buy Fair Act (HB 1282), making Washington the first state to require embodied carbon reporting for concrete, steel, and wood in state building projects. (WA Commerce: Buy Clean Buy Fair | Carbon Leadership Forum: BCBF)

2025: Climate Action Plan progress report and new plan ordered#

The September 2025 2013 CAP Progress Report found that Seattle completed or made significant progress on 88 of 148 actions, contributing to a 5.7% reduction in greenhouse gas emissions from 2014 to 2022. However, the report confirmed that Seattle is not on track to meet its 2030 targets. In April 2025, Mayor Harrell signed an executive order directing development of a new One Seattle Climate Action Plan, expected in Q3 2026. (Seattle OSE: CAP Progress Report | Seattle OSE: One Seattle CAP)

How the city manages climate policy#

Office of Sustainability & Environment#

OSE leads citywide climate strategy, manages building energy programs (benchmarking, tune-ups, BEPS), coordinates the Green New Deal, and publishes the greenhouse gas emissions inventory. OSE also oversees the Climate Portal, a public data tool for tracking emissions across sectors. (Seattle OSE: Climate Data & Planning)

Funding#

Seattle’s climate programs are funded through multiple sources:

  • JumpStart Payroll Expense Tax: Generated $315 million in 2023; funds Green New Deal programs, affordable housing, and the Environmental Justice Fund (Cascade PBS: JumpStart Revenue)
  • Washington Climate Commitment Act: State cap-and-invest revenues fund local transit, electrification, and resilience projects
  • Seattle City Light: The city’s municipally owned electric utility delivers approximately 90% carbon-free electricity — 88% from hydropower — making building electrification an effective decarbonization strategy (Seattle City Light: Hydropower)
  • Federal grants: Inflation Reduction Act and other federal programs fund building retrofits and EV infrastructure

Interagency coordination#

Climate policy spans multiple city departments: SDOT manages transportation emissions reduction and EV infrastructure, Seattle City Light manages the electricity grid and efficiency programs, Seattle Public Utilities manages waste reduction, and SDCI enforces the energy code for new construction.

Advocacy organizations#

  • 350 Seattle: Local affiliate of 350.org focused on fossil fuel divestment, building electrification advocacy, and climate justice organizing.
  • Sierra Club Washington: Campaigns for clean energy, climate policy, and environmental protection at city and state levels.
  • Front and Centered: Statewide coalition of communities of color and frontline organizations leading on climate justice policy, including the HEAL Act.
  • Carbon Leadership Forum: University of Washington-based research collaborative that develops policy on embodied carbon, including research that informed Washington’s Buy Clean Buy Fair Act.

Data sources#

Seattle Climate Portal#

Map-based tool providing greenhouse gas emissions data by sector, along with indicators for energy use, transportation, and building performance.

Access: Seattle OSE: Climate Data & Planning

Energy benchmarking data#

Published building-level energy performance data for Seattle’s 3,700+ largest buildings. Searchable by address.

Access: Seattle OSE: Energy Benchmarking

Heat Watch Map#

Air temperature data from the 2020 Seattle/King County heat mapping campaign, showing neighborhood-level heat variations during extreme heat events.

Access: Seattle Trees: Urban Heat

Washington Environmental Health Disparities Map#

Census-tract-level rankings of environmental and health disparities statewide, including heat exposure and pollution burden. Required under the HEAL Act.

Access: WA DOH: Environmental Health Disparities Map

Key statistics#

MetricValue
Building share of Seattle emissions~40%
Transportation share of Seattle emissions~60%
2030 emissions reduction target (from 2008)58%
Actual emissions reduction (2014-2022)5.7%
Waste sector emissions reduction (since 2008)31%
Transportation emissions reduction (since 2008)14%
Building emissions reduction (since 2008)6%
2013 CAP actions completed or in progress88 of 148
Buildings covered by benchmarking3,700+
Households converted from oil heat2,000+
BEPS net-zero target date2041-2050
Population living on heat islands (8°F+)54%

Sources: 2013 CAP Progress Report | Seattle OSE: Buildings & Energy | Axios Seattle: Heat Islands

Last updated: February 2026