This blog explores data about heating fuel and housing characteristics presented in interactive visualizations on CETI’s Northwest Clean Energy Atlas.
According to data from the Environmental Protection Agency (EPA) presented on CETI’s Northwest Clean Energy Atlas, the residential sector currently accounts for nearly 10% of Northwest emissions, with heating accounting for a significant portion of those emissions. Fortunately, there are decarbonization solutions to tackle the emissions produced by residential heating in Idaho, Montana, Oregon, and Washington. This blog explores the heating fuels used in Northwest homes and describes the most cost-effective and efficient means to decarbonize residential heating.
Before we explain the path to decarbonized heating, we need to answer the question: how are homes currently heated across our region? This is where we turn to the 2022 American Community Survey (ACS) for Housing Characteristics, which collects data on total housing units in each U.S. county, including housing characteristics such as primary heating fuel used (see here for a national view on residential heating fuels using ACS data).
In this blog, we focus on residential heating in the Northwest and look at how housing occupancy (owner vs. renter), building size, and building age might shape our plan for decarbonization. The ACS data registers roughly 5.8 million housing units in the Northwest, nearly all of which are heated by one of three named energy sources: electricity, natural gas, and propane (bottled, tank or LP gas, see Figure 1 below).
Electricity-based heating, typically in the form of electric resistance (i.e., hot coils), and natural gas heating, typically in the form of gas furnaces, combine to heat nearly 90% of all housing units. Propane is the third most common specified fuel, heating just under 4% of Northwest homes.
Next, we examine the ACS data at the county level to identify where each heating fuel is most prevalent (Figure 2).
Most homes in Oregon and Washington—the most populous states in the Northwest—use electricity for heating, typically in the form of electric resistance heating. Electric heating is also prevalent for select counties in southern Idaho.
Montana and Idaho, on the other hand, have more homes heated by natural gas. Areas in western Oregon, as well as pockets of eastern and western Washington also have high concentrations of natural gas heating; this spatial pattern is consistent with the layout of natural gas pipelines, as seen in the middle map of Figure 2. Homes with access to natural gas may choose this heating fuel due to its historically cheaper price compared to the price of residential electricity. However, natural gas is subject to greater price volatility relative to electricity, such as the rapid price jumps observed during the COVID19 pandemic.
In Montana, residents without access to natural gas pipelines are likely to use bottled or tanked propane: for 10 counties in the state, over 45% homes use propane for heating. Residents may choose propane over electric heating for multiple reasons, such as the average price of propane being slightly cheaper than the average price of residential electricity in 2022,[1] or the fact that on-site propane is potentially more reliable than electricity during storms or cold winters.
Additional housing characteristics may also play a role in heating fuel differences, as seen when we break down the ACS data by building size and ownership (Figure 3).
The Northwest housing stock is primarily made up of owner-occupied, single-family homes. These units are most likely to use natural gas for heating, contrasting with renter-occupied units, which are most likely to be apartment buildings (10+ units) and heated by electricity.
Lastly, we take a look at the range of ages for Northwest housing structures (Figure 4). Nearly half of all housing units in the Northwest were built 45 years ago or earlier, with over 20% built before 1960. Updating and retrofitting this older housing stock may raise some challenges or come with greater costs. However, the middle-aged housing stock, built between 1980 and 1999 may reveal an opportunity, as homes this old typically require updates to their electrical systems anyway. Thus, we may be able to synchronize the wiring repairs with heat pump installations, potentially minimizing the costs of achieving clean energy heating systems in older buildings.
CETI’s Net-Zero Northwest Energy Pathways-Buildings study found that electrifying residential appliances is a more cost-effective and energy-efficient strategy to reach net-zero emissions than retaining and decarbonizing the residential appliances that use gas. Hence, the desired decarbonization strategy is to deploy efficient, electric-powered heat pumps, which work by moving hot and cold air between a home and its surroundings.
Heat pumps can yield zero-emission heating when powered by clean electricity, making them a great fit for the Northwest states, which already have some of the cleanest electricity in the country. Heat pump technology has also improved significantly and can now be used effectively in cold climates (albeit with lower efficiency).
Not only can heat pumps produce no emissions, but they can also be more energy efficient than both natural gas furnaces and electrical resistance heating. In fact, heat pumps can achieve energy efficiencies exceeding 100%, meaning that they can move more energy (in the form of heat) than the energy (in the form of electricity) they need to run. This efficiency ultimately reduces energy consumption and, as a result, customers’ heating bills. It is important to note that today the high upfront cost for heat pumps is still prohibitive for many customers, so continued efforts are required to bring down the cost and make this decarbonization solution accessible to consumers.
As rising summertime temperatures motivate more Northwest residents to invest in cooling systems, heat pumps are a two-for-one solution because they offer heating and cooling within a single home appliance.
So where do we go from here? With the insights gained from the ACS data, it appears we can apply a two-pillar approach: 1) convert current electrical resistance heating systems to heat pumps, and 2) convert natural gas heating systems to electricity-powered heat pumps.
Prioritizing decarbonizing single-family homes would address the largest contingent of natural gas heating systems. Although occupants could expect long-term savings by switching to energy-efficient electric heat pumps, the upfront costs of converting from gas heating systems pose a significant challenge to making the transition.
Retrofitting homes that already have electric-resistance heating systems presents a potentially easier opportunity, since these homes may be able to switch to heat pumps without upgrading electrical panels. With both approaches, ensuring an equitable clean energy transition will require that heat pumps are accessible to low-income residents to ensure these customers are not left behind with gas heating systems while gas rates rise as more and more customers transition off gas appliances to electric heat pumps.
Converting HVAC systems in Northwest homes to energy-efficient heat pumps is an effective and feasible, if not yet widely economic, way to reduce emissions from residential heating. The Northwest Energy Efficiency Alliance reports that approximately 25% of single-family homes already used some form of heat pump in their heating systems in 2022 (up from approximately 15% in 2017). Multi-family homes, on the other hand, have a greater gap to close, as less than 5% of multi-family units in the Northwest currently use heat pumps to heat their units.
Decarbonizing residential heating with electric heat pumps will move the Northwest closer to a net-zero economy and provide residents with an efficient and affordable way to heat—and cool—their homes.
[1] The price of propane ($ per gallon) can be compared with the price of electricity ($ per kWh) since 1 gallon of propane contains the same amount of usable energy as approximately 27 kWh of electricity.
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