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Seattle’s Building Emissions are Rising – Here’s What the Data Tells Us

Seattle’s buildings are responsible for more than one-third of the city’s core greenhouse gas emissions – and rising. According to the most recent greenhouse gas inventory, climate-polluting emissions in buildings increased 8% between 2016 and 2018, driven by burning fossil fuels like fracked gas and oil for heat, hot water, and cooking.

Seattle’s Energy Benchmarking Program collects and analyzes building energy performance data from more than 3,500 of the city’s largest commercial and residential buildings (more than 375 million square feet!). By comparing this data over time, we can investigate what’s happening with the City’s larger buildings (over 20,000 SF) to identify trends and create data-driven policies and programs in response.

Fossil Gas Driving Emissions in New Construction

If you thought the cranes dotted across Seattle’s skyline were increasing in recent years, you were right. Between 2016 and 2019, Seattle added more than 200 new large buildings (over 20,000 SF), representing over 50 million square of new construction. This continues a trend from past benchmarking reports where we are seeing an increase in the average height and size of new buildings. In fact, over 40% of Seattle’s building area from these larger buildings has been built since 2000.

Newer buildings generally are larger and have more amenities than older buildings, and are on average more energy efficient and have higher ENERGY STAR scores. But since many of these buildings are being built with fossil gas-powered hot water and heating systems – and because they are bigger the overall greenhouse gas emissions continue to increase.

Recent updates to Seattle’s building energy code to eliminate fossil fuels for most space and water heating for new buildings will go a long way to cap growth in greenhouse gas emissions from any new larger buildings, but these changes will take time to phase in and be reflected in future benchmarking reports.

Existing Buildings are Reducing Electricity Use – But Not Fossil Fuels

From 2014 to 2019, total greenhouse gas emissions from existing benchmarked buildings increased 0.4% even as total energy use decreased 8.3%. Though the construction boom is driving overall higher energy use and climate-polluting emissions, a lot of older buildings have continued to improve energy efficiency – driven primarily by steady reductions in electricity use.

Since 2014, electricity use for buildings reporting complete data for all six years (2014 to 2019) has decreased almost 9% in total. But at the same time, fossil fuel use in the same buildings has increased slightly – on-site fossil gas and district steam use (which is generated from fossil gas) increased 1.4% from 2014 to 2019. Since Seattle’s electricity generation has almost no associated greenhouse gas emissions, the substantial savings in electricity use translated to little emissions reductions for these buildings.

In Seattle, fossil gas has about twelve times the amount of carbon emissions per unit of energy than electricity. As a result, from 2014 to 2019, total emissions from existing buildings increased even as total energy use decreased substantially. This highlights the need for more concerted efforts to reduce fossil gas use in existing buildings in addition to the new energy code updates for new buildings and Seattle’s other building policies.

Building Emissions are Distributed Across a Range of Building Types

For these benchmarked buildings, greenhouse gas emissions are spread across a wide range of different types of buildings, shown below. Hospitals, labs, grocery stores, and hotels tend to have the most emissions per building, but we have fewer of them. Multifamily (over 20,000 SF) and office buildings have a much smaller emissions footprint per building but make up a similar amount of total greenhouse gas emissions as these other types because we have a lot more of these buildings.

GHG emissions by building type (click to enlarge)

To help transition existing commercial and multifamily buildings off fossil-fuels and onto clean electricity to meet our climate goals, the City is exploring greenhouse gas emissions targets for larger buildings – paired with equity-centered support and incentive programs. To achieve the goals of the Climate Action Plan, Seattle’s emissions reductions rate needs to increase substantially. Find out how an emissions targets can help on our Building Performance Standards page.

To learn more about the Benchmarking program and how we use this data, see our new Benchmarking website.

Explore individual building reports on our Benchmarking map and reports site.