Green Building Isn't Enough; We Need Green Zoning.

How can cities that have green building codes have zoning bylaws that protect low-density single family housing?

These days it seems that everyone is fighting over zoning. Housing costs in many cities are unaffordable but the great proportion of the cities are locked into single-family zoning and building anything but a detached house seems almost impossible. Right now we see these battles in Seattle, San Francisco, and Toronto, but they are happening just about in every successful city.

And the hilarious thing about it all is that these are also cities that have green building standards. San Francisco has a green building code designed to reduce energy use, Seattle's green standard "saves resources and promotes renewable, clean energy", Toronto's standard's intent is to "reduce energy use and greenhouse gas emissions."

The great hypocrisy is that the single biggest factor in the carbon footprint of our cities isn't the amount of insulation in our walls, it's the zoning.

Urban form and Energy consumption/Public Domain

The Archetypes study by Natural Resources Canada demonstrated this a decade ago; here is an example from Calgary, where the people living in the leaky old buildings in Mission use a fraction of energy inputs as the people living in suburban Lake Bonavista- they live in smaller apartments and don't have to drive everywhere.

We have been saying it for years: denser urban living is the key to reducing our carbon footprint. Some, like David Owen, call for really high density; I have called for the Goldilocks Density; the fashionable phrase now is the missing middle; both describe density high enough to support local businesses so that one can mostly get around by walking, but buildings that are low enough that they can be efficiently built out of low carbon materials like wood.

Alex Steffen has written in Carbon Zero:

Urban density reduces the number of trips residents take in their cars, and shortens the distance they drive for the remaining trips. It is possibly the best-documented fact of urban planning that the denser the neighborhood (all other things being equal), the less people drive, and the more their transportation emissions drop.

The Influence of Urban Form on GHG Emissions in the U.S. Household Sector /via Environmental Science

Everybody knows this; there have been dozens of studies that prove it. One that wasn't paywalled, The Influence of Urban Form on GHG Emissions in the U.S. Household Sector, showed that "doubling population-weighted density is associated with a reduction in CO2 emissions from household travel and residential energy consumption by 48% and 35%, respectively." It concludes that "given that household travel and residential energy use account for 42% of total U.S. carbon dioxide emissions, these findings highlight the importance of smart growth policies to build more compact and transit friendly cities as a crucial part of any strategic efforts to mitigate GHG emissions and stabilize climate."

Yet when cities approve higher densities, they do it just in pockets and strips, around the Main Streets, many of which are louder and more polluted. The density isn't spread around but is spiky, avoiding the established and protected single family houses. Instead, it should be everywhere, "like butter across a piece of bread."

Looking at Toronto, Planner Gil Meslin has been documenting examples of "missing middle" housing that was built before the city formalized its zoning and stopped this kind of development.

They are very popular places to live in wonderful, quiet residential neighbourhoods and they co-exist just fine. Yet you can't do them now, even though they could create thousands of more affordable units. Instead, all the apartments are crowded into former industrial areas or onto noisy main streets where residents recently had to go to war with the Mayor over his plan to have all road work done at night.

We have been talking about the relationship of density and carbon for years, and we have been talking about green building codes, certifications and bylaws. But green building isn't enough; we need green zoning. Any civic government that calls itself green while protecting low density single family housing is just being hypocritical.