In the Older, Smaller, Better report, the Preservation Green Lab analyzed assessor data and established key measures of the age, age diversity, and granularity of built fabric at the 200-meter-by-200-meter level. Here, warmer-colored shapes show older buildings in San Francisco’s Hayes Valley, constructed before 1945. Buildings shaded blue and green were constructed between 1945 and today.| Credit: Preservation Green Lab mapping of data from the City and County of San Francisco.
Tomorrow, the National Trust’s Preservation Green Lab
will release its newest report, Older, Smaller, Better: Measuring how the character of buildings and blocks influences urban vitality
. Over the past year, the Green Lab team analyzed mountains of data to assess the statistical relationships between the age and size of buildings and 40 key measures of social, cultural, economic, and environmental vitality. The report represents the culmination of efforts to distill and analyze approximately 1,500 data files collected from a variety of public and private sources. For those interested in exploring “Big Data
” and learning how to explore the character and performance of older buildings in their own communities, here is a look at key sources of information:
- Local property assessors hold critical data on the characteristics of buildings and parcels, such as the date built, number of stories, and footprint of all existing structures. Assessors’ data also includes information on property values and the location of vacant lots. In Older, Smaller, Better, Green Lab researchers overlaid a 200-meter-by-200-meter grid across the cities of Seattle, San Francisco, and Washington, D.C., creating a web of thousands of equally sized grid squares. The Green Lab used county assessors’ data to compute each grid square’s median age of buildings, diversity of building age, and size of buildings. These calculations were combined into a single “Character Score” metric for each grid square.
- The U.S. Census Bureau remains a go-to source for data on characteristics of populations and housing. Data from both the 2010 decennial census and the American Community Survey, which is distributed to a subset of the U.S. population on an annual basis, were analyzed and explored in the new Green Lab report. The census itself offers useful data on population and housing density, race and ethnicity, and age of residents. Because the census is sent out to the entire nation, a considerable amount of information from the decennial census can be specified at the block level. Data from the American Community Survey (ACS), meanwhile, includes additional information about income, employment status, nativity, geographic mobility, and educational attainment, but because it is distributed to only a small portion of the U.S. population, ACS data can only be reliably extrapolated at a larger geographical scale. From census and ACS data, the Green Lab’s research team developed measures of population density, median income, employment status, age of residents, racial and ethnic diversity, age diversity, and income diversity.
The Census Bureau’s Center for Economic Studies also provides valuable data. The Center’s Longitudinal Employer-Household Dynamics (LEHD) program and accompanying Origin-Destination Employment Statistics (LODES) subprogram contain detailed information on the locations of jobs, including data parsed according to the size of an employer and its industry. This data is available at the census block level, making it highly valuable for research efforts that analyze the characteristics of small sections of cities. The Older, Smaller, Better team used this data to determine where there are greatest concentrations of jobs, jobs in small businesses, and jobs in creative industries.
| To assess the performance of older, smaller buildings, the Preservation
Green Lab developed data “mash ups” that combine information on
buildings across the entire cities of San Francisco (pictured here),
Seattle, and Washington, D.C., with data from a variety of other
sources. | Photo: Jim Lindberg.
- Nowadays, many cities across the country offer their own open data portals, which allow anyone to download a variety of data and geographic information, from the shapes of buildings to the locations of bike paths and the sources of 911 calls. City portals often also include construction and demolition permit data. The Green Lab used open data portals in the three study cities to map the locations of development and demolition activity, sidewalk cafes, bike share stations, farmers markets, women and minority-owned businesses, and new businesses. In some cases, it proved necessary to reach out to city staff for additional information.
- One of the Green Lab’s collaborators on the report, Impresa, Inc., had access to data on the intensity of cellphone usage in different areas of the city and different hours of the week. They analyzed this data and shared the results of the analysis with the Green Lab. Combining data on the age and size of buildings with data on cellphone usage at Friday night at 10:00 p.m., the Older, Smaller, Better report definitively shows that areas with older, smaller, mixed-vintage buildings attract greater nightlife activity than areas with mostly newer, larger buildings. The Green Lab also explored the use of data from third party websites like Walk ScoreTM, Flickr, Craigslist, and others. The Green Lab’s Seattle neighbors at Walk ScoreTM shared data on the walkability, bikeability, and transit accessibility of Seattle, Washington, D.C., and San Francisco. Craigslist data pointed to areas with greatest diversity of residential rent offerings.
Stay tuned to the Preservation Leadership Forum blog to download the report tomorrow
and read more about the study’s findings. Read these additional posts
on the Older, Smaller, Better
report.#Sustainability #OlderSmallerBetter #PreservationGreenLab