The latest UN Climate Change Report draws no blow: Human activities are contributing to climate change “at a rate unprecedented for at least the last 2000 years.” And two of the biggest components of the household’s carbon footprint are transportation and household energy consumption, both of which are correlated with where people live.
More specifically, suburban households have larger CO2 footprints than their urban resistances because they are more dependent on solo commuting and non-commuting, travel longer distances, and live in larger homes that require more energy to heat and cool. Low-density neighborhoods also require more-and-more-expensive infrastructure to provide basic services such as water, sewerage and roads.
For the United States, reducing harmful greenhouse gas (GHG) emissions will require changes in our urban development patterns: building smaller, more energy-efficient homes in areas close to jobs and public transportation; enable retail and walking or cycling services within the home; and the development of more robust non-car transport networks connecting homes, workplaces and other economic activity centers.
The Washington, DC metro area offers a useful lens on how development patterns over the past 30 years have affected both climate issues and affordability. The vast majority of new homes have been built in suburbs or suburbs of low density — far outside existing public transportation networks. The fastest growing communities are over 30 miles from the region’s primary employment center. Since 2010, multi-family housing accounts for an increasing share of new housing – a net gain for climate impacts – but this shift reflects a sharp decline in the total volume of housing construction, exacerbating concerns at affordable prices.
In this report, we analyze where Washington, DC, the region has – and has not – built housing from 1990 to 2019, particularly focusing on proximity to public transportation and jobs.
Public transportation and jobs in the Washington, DC region are highly centralized. New homes are not.
The geographic distribution of economic activity in the Washington, DC metro area follows a pattern typical of many older cities. Job is highly concentrated within 5 kilometers of the central business district (CBD) in the center and much less close to suburbs and suburbs. The two largest suburbs, Fairfax County, Va. And Montgomery County, Md., Is also home to significant job clusters.
The region’s Metrorail system is designed to facilitate traditional commuting from city to city center through a hub-and-own design (Figure 1). The District of Columbia has the closest proximity to public transportation (Metrorail and bus) as well as dense street networks with pedestrian and bicycle infrastructure. The Metrorail network extends along two corridors in Montgomery County (northwest and northeast of the district) and west through Fairfax County; Most of the land in these counties is not adjacent to high frequency transit. Work is underway to expand the Metrorails Silver Line to Dulles Airport in Loudoun County, Va .; these stations are expected to start operating in 2022.
Large employment centers and transit infrastructure are sustainable features of the built environment that persist for many decades. Therefore, a climate-friendly growth strategy for the region would concentrate new housing, retail and services around these existing locations.
However, most of the region’s housing growth in the last 30 years has taken place in suburbs and suburbs, far from the CBD and in areas not well served by public transport. From 1990 to the Great Recession, fewer than 10% of all permitted housing was in the city center, compared to about 40% in the suburbs and a little more than half in the suburbs. The amount of new housing built in the region as a whole began to decline in the early 2000s – well before the Great Recession. As of 2019, new home permits still lowered the level before the recession — an ominous sign of affordability.
Housing growth in the city center has grown significantly since the early 2000s, when almost 60% occurred in the district. Suburban jurisdictions have shown the slowest recovery since the Great Recession. Fairfax County – the largest jurisdiction in the region, with over 1 million inhabitants – issued on average permits for more than 5,000 new homes per year from 1992 to 2005, but has averaged fewer than 1,800 units per year from 2010 to 2019.
The suburban counties – particularly Loudoun and Prince William counties in Virginia – experienced explosive growth in the late 1990s and early 2000s followed by a sharp decline and are currently reaching levels similar to the beginning of 1990s.
The growing share of new development in the city center is a net positive for climate resilience because these jurisdictions have the highest density of jobs and the best access to non-car transport. But the collapse of new homes in Fairfax and Montgomery counties leaves a huge gap in the region’s overall supply. Investments in new Silver Line stations around Tysons Corner in Fairfax have spurred localized housing development, but it is far below total production in the 1990s. Between 60% and 70% of new homes each decade were built in counties that do not have Metrorail stations – a recipe for greater car dependence, longer commutes and increased greenhouse gas emissions.
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Denser communities attract more housing growth
Examining the underlying causes of whether or not housing has been built in particular counties is far beyond the scope of our analysis, but a simple exercise may preclude a hypothesis: The decline in housing growth is not due to a lack of available land. During the 1990s and 2000s, new housing permits were negatively correlated with the original housing density — low-density communities built more homes. But this relationship has reversed in the 2010s, causing housing growth to correlate positively with density.
The district has the smallest amount of undeveloped land among the jurisdictions of the metro areas, and has nevertheless increased production. Both Fairfax and Montgomery counties have abundant open space but have low density development. The median value for the home in both counties is well over $ 500,000 – an indicator of strong housing demand. The Washington, DC region’s tendency for concentrated housing growth in the dense urban center and stagnant supply in affluent suburbs reflects other parts of the country.
The type of housing being built is also important for climate impacts. Single-family homes consume more resources for construction, maintenance and operation than apartments in multi-family buildings.
As the location of housing growth has changed in the Washington, DC region, the composition of new development has shifted toward apartment buildings (defined as five or more units per building). From 1990 to 2005, approximately 25,000 single-family permits were issued each year against approximately 7,500 multi-family units. From 2010 to 2019, single-family permits averaged about 12,000 a year, slightly more than the number of multi-family permits.
Throughout the period, a trivial number of permits were issued for duplexes, triplexes and fourplexes – a point of interest for current discussions on zoning reforms to legalize this type of small apartment buildings in places where they are currently not allowed.
The shift towards a larger share of multi-family housing primarily reflects geographical changes in where new development took place, as well as changes in the composition of housing within a few jurisdictions. Figure 6 shows the number of multi-family and single-family permits for the largest urban areas and suburbs and the two largest suburbs. Almost all growth in housing permits in the district comes from apartments in multi-family buildings, while single-family production remained very small. Most newly built single-family houses in the city center are demolitions that replace existing single-family houses, so it does not represent a net increase in the housing supply.
Loudoun County, on the other hand, has experienced minimal growth in multi-family permits over time; changes in composition are solely due to changes in the level of single-family permits. The two major suburbs, Fairfax and Montgomery counties in particular, show different patterns: Fairfax County has experienced a steady decline in the level of both single and multi-family permits, while single- and multi-family permits in Montgomery County have moved in opposite directions.
A housing characteristic that has important consequences for climate impacts, but which we can not observe in our data, is the amount of area used per hectare. Housing (or sub-sizes for single-family houses). The Census Bureau’s permit data groups single-family separate and attached (townhouse) structures together and contains no information on party sizes. Because terraced houses use significantly less land per. House than detached houses, a shift within the single-family category towards more terraced houses can result in significantly higher housing density. Future analysis of new housing density using alternative data sources would be valuable.
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Changing trends in housing growth are a mixed bag, environmentally speaking
The Washington, DC region’s housing growth over the past 30 years has had mixed consequences for climate impacts. Increased housing supply in the city center (especially in the district) means that more households can live close to the region’s largest concentration of jobs and have relatively good access to public transport. Most new homes in the city center are in multi-family buildings that have a smaller CO2 footprint per. Household than single-family houses.
On the other hand, the continued rapid growth of single-family homes in the suburbs means that the majority of additional households in the region locate in car-dependent locations far away from job centers and live in coal-intensive homes. And the overall decline in the region’s housing production compared to the 1990s raises serious concerns about affordable prices. Housing prices have been rising faster than incomes, putting greater economic pressure on many households. Strong demand combined with insufficient supply is the perfect recipe for sharply rising housing costs.
Our analysis focuses on fairly large geographical areas – cities and counties – while other research finds a significant variation in housing growth patterns within the individual jurisdictions. In the district, most housing growth was concentrated in a handful of neighborhoods, including moderate-income majority-black neighborhoods like Shaw and Brookland, or formerly non-residential neighborhoods such as NoMa and the Southwest Waterfront. Meanwhile, the district’s most affluent, primarily white neighborhoods added almost no new housing.
The absence of development in job- and transit-rich centrally located neighborhoods throughout the district, Fairfax County and Montgomery County reflects both formal rules — low-density zoning and historic preservation — and the political impact on longtime homeowners who organize to oppose change. These efforts toward growth from affluent societies harm more than the physical environment; they also exacerbate perennial economic and racial inequality and push low-income households into longer commutes from distant suburbs.
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Data and methodology notes
Data about housing permits were taken from the Census Bureau’s New Residential Construction Series. Information on the location of transit stations was obtained from the US Department of Transportation. Dates of recessions were obtained from St. Louis Federal Reserve Economic Data (FRED). Graphs of housing permits by year are shown as three-year rolling averages to reduce annual noise. Crosswalks between location and county codes use the MABLE Geocorr application. Matching latitude-longitude coordinates for county transit stations used the Federal Communication Commission’s Block API.
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