FACT - Infill Homes Reduce Climate Emissions
***Written in coordination with our partners at 350 Silicon Valley Palo Alto Climate Action.***
One of the best ways to protect the earth from the impact of climate change is to build new infill homes, as we’ve written before. Yet many still do not recognize this as fact.
Even when faced with our extremely imbalanced city’s jobs-to-housing ratio – where our local teachers, police, firefighters, service workers, and computer engineers must suffer through hours-long super-commutes to get here from distant homes. We fail to acknowledge the harmful greenhouse gas (GHG) emissions that result.
However, the data prevails. Two new reports from the Terner Center at UC Berkeley demonstrate that to protect our planet’s climate, we must change Palo Alto’s zoning laws to allow more infill homes. Change begins right here.
A Tailpipe of Two Cities
The first Terner Center report examines the relationship between driving, GHG emissions, and residential density in a few Bay Area cities. There is an overwhelming correlation between density and lowered GHG emissions.
The differences between Palo Alto and San Francisco are particularly stark. We are much more likely, compared to our neighbors to the north, to take a trip by car as opposed to bus, bike, or foot (77% of all trips versus 58%). Moreover, we drive 50% more miles per day (15 miles versus 10). Accordingly, our tailpipe GHG emissions are 50% higher.
A big contributing factor: our population density, measured in people per square mile, is one-sixth of San Francisco’s.
It gets even worse when we move to Oakley, where the Bay Area meets the Central Valley. Like many more-recently built suburbs (it had fewer than 3,000 residents in 1980), it has a low ratio of jobs to homes (0.3), and a long drive to jobs in San Francisco (51 miles). Compared to Palo Alto, residents of Oakley drive twice as many miles per day (30 miles versus 15), and their tailpipes emit twice as many GHG emissions (4.1 tons versus 2.1).
Every home we don’t build in Palo Alto is a home that instead gets built at the Bay Area’s periphery. This means much more driving and tailpipe pollution.
Follow the Social Science
The second Terner Center report reviews the links between home production and climate protection. It’s not just that people living in denser neighborhoods drive less and thereby reduce their tailpipe GHG emissions. It’s also that multi-unit homes with shared walls are less energy intensive to build and heat/cool once complete. Specifically:
The authors found that attached homes use 41% less energy than detached homes, based on their analysis of federal survey data.
A study found that shared walls in attached homes contribute to reduced energy consumption by residents, independently from other factors like floor space and residents’ income.
A study found that shared walls in attached homes also contribute to reduced GHG emissions from home construction, including materials manufacture.
Studies find that greater population density correlates with less driving and thus with fewer GHG emissions.
Finally, a study found that enabling more infill homes is the most powerful policy lever available to city governments in California.
Moving FORWARD Together
Palo Alto Forward offers a blueprint to build new infill homes. To reduce GHG emissions by constructing new infill homes, we must raise limits on building height and size (a.k.a. floor area ratio); eliminate density limits and one-size-fits-all parking mandates; reduce impact fees; and speed up permit timelines.
Environmental policy must be equitable. That means building new infill homes for people at all income levels. This will require large scale zoning changes and government subsidies. We also need renter protections to prevent displacement.
In the words of the Terner Center, we must “align climate-friendly land use reforms with affordability, equity, and environmental justice goals.” And that is what Palo Alto Forward is all about.