Here is a guest post from Chad Newton, who I met at our ill fated Roosevelt happy hour. Chad describes himself as “a sustainability enthusiast, data geek and environmental engineer at Gray & Osborne, Inc. in Seattle.” He’s also responsible for Build the City, an awesome data driven blog about global urban and environmental but with a focus on Seattle. Build the City has some of the best maps based on 2010 census data that I’ve seen.
I have created a map of average household size in the City of Seattle based on the U.S. Census 2010 data (other census maps are posted at Build the City. Planners typically use an average household size between 2 and 3 over wide areas to calculate other planning variables. But household size itself is a variable that varies with neighborhood and housing type. The map below shows average household sizes for Seattle, on the basis of census block groups. The data from the U.S. 2010 Census is not without flaws, particularly around universities, where I suspect some dorms are counted as single housing units. But its the best we got.
There is a clear trend visible in the map (larger version here), with downtown and adjoining neighborhoods, together with a few urban villages, having the lowest household sizes. The largest household sizes are found in southeast Seattle neighborhoods with an abundance of subsidized family housing.
Do families instinctively eschew urban neighborhoods such as downtown? Perhaps, but we haven’t really given larger households options. Redfin, a popular real estate listing website, shows 677 studio, one and two bedroom homes for sale currently in central Seattle, and only 63 three bedroom and larger homes. Some recent downtown luxury high-rises (like 1521) have included large units at high prices, so there must some demand. Why are three bedroom apartments and condos so rare in the city, particularly affordable ones? The economics of new construction play a factor: people will pay more per square foot for a tiny one bedroom unit than for a larger home. Based on a quick review of rental prices in a few apartment complexes, three bedroom homes rent for 50 to 67 percent more than one bedroom homes, despite having proportionately more space.
Larger homes in urban neighborhoods to increase diversity and support a full lifecycle environment. Three and four bedroom apartment flats are common in European cities, where they are often house one extended family or are shared by flatmates. Sharing apartments or houses leads to a lower cost per person, a benefit for consumers and affordable housing. Sharing of homes results in more efficient use of appliances and utilities, a benefit to the environment versus everyone living in separate one bedroom apartments. But larger urban apartments could result in lower profits for developers and building managers.
A potential solution to the dearth of family-sized housing in the urban core: the City’s existing Multi-family Tax Exemption program could be tailored to support affordable three bedroom and larger units.