The environmental case for density
In addition to making housing more affordable, zoning reform can reduce carbon footprints and improve service access.
There is a growth of interest in the role of land use policies in housing debates. Evidence from American and Canadian cities shows that increasing the density of housing makes it both more accessible and affordable. Denser neighbourhoods can be achieved by amending municipal zoning codes to build more houses on a single plot of land (a process also known as upzoning). But there is another advantage to zoning reform that extends beyond the economics of housing: if cities allow for greater housing density, they can also fight climate change.
In fact, climate change policy wonks can draw on observations from affordability debates to advance municipal net-zero carbon objectives. This is because much of North America’s residential development has been constrained by restrictive zoning policies that favour low-density residences like single-family homes. Gil Meslin, a Toronto-based urban planner, calls this phenomenon the “yellowbelt” when describing his city’s preference for detached houses.
As is the case in other cities, the yellowbelt is crucial to understanding why Toronto’s housing is becoming unaffordable for low- and middle-income residents. A MapTO article points out that restrictive zoning policies force developers to either: a) pay steep acquisition costs which are eventually passed on to buyers and renters, or b) reinforce the problem through the construction of more single-family units. Given that current rules make the latter option more palatable, developers are forced to comply with pro-suburb yellowbelt policies.
Unfortunately, the problems of restrictive zoning don’t stop at artificially creating housing scarcity. Yellowbelts around the world are contributing to climate change.
The preference for low-density housing among municipalities leads to sprawling growth that crowds out space for agricultural and conservation purposes. The creation of suburbs through urban sprawl takes away land that could be used for wetlands and farming. These so-called “leapfrog” patterns of low-density sprawl also encourage greater car usage as commercial and industrial areas are often zoned into separate and distant districts. This represents a triple-threat policy failure where exclusionary zoning can have a serious impact on housing access, nearby ecosystems, and public health.
By reducing dependence on single-family detached homes (through zoning relaxation and intensification) it is possible for cities to play a proactive role in improving housing affordability and accessibility. And these benefits can extend to municipal net-zero objectives!
For starters, upzoning can reduce urban sprawl. When cities express a preference for denser housing, developers can build multi-dwelling residential apartments closer to urban cores, rather single-family houses in new suburbs.
By better utilizing space closer to existing services and neighbourhoods, policymakers can rely less on unsustainable development in peripheral communities or near greenbelts. Additionally, upzoning can reduce energy and consumption for urban dwellers. Not only can multi-unit zoning lead to walkable services and accessible transit for renters and homebuyers; it can reduce per-unit heating and hydro costs significantly — even more so when part of a transit-oriented development project.
In addition to reducing utility bills for tenants, upzoning can also make construction sectors more sustainable. As I will discuss in a future piece, construction materials are responsible for around 20% of the world’s greenhouse gas (GHG) emissions. A 2020 study by Adrian Smith + Gordan Gill Architecture examined the operational emissions (through heating, power, etc.) and the embodied carbon (through construction, material production, etc.) of different building types in Chicago. They found that mid- and high-rise apartments, while emitting higher overall levels operational GHG emissions, had the lowest levels of embodied carbon per unit.
Although there is a clear advantage for 200-unit and 500-unit buildings, it is important to note that embodied carbon can be reduced for all forms of housing when greener materials like cross-laminated wood are used in construction. But due to supply shortages and cost constraints, the incorporation of these resources is unlikely to be adopted without government support.
Two developments in Vancouver could set a precedent for linking green construction practices to improved housing access. In the central neighbourhood of Fairview, the Canada’s Earth Tower aims to become the world’s tallest hybrid wood structure. Through the addition of over 200 units, the 40-storey structure will source local timber to help construct a net-zero building in the heart of British Columbia’s largest city.
In nearby Kitsilano, the Squamish First Nation plans to construct Sen̓áḵw — a development consisting of 12 multi-storey buildings (11 of which are residential) on its territory that will add almost 6,000 units to Vancouver’s rental market. Thanks to their territorial sovereignty, the First Nation is able circumvent Vancouver’s NIMBY zoning rules to break ground on a project that will include over 900 affordable homes. Using similar building techniques to those being employed for the Canada’s Earth Tower, Sen̓áḵw is expected to become Canada’s largest net-zero carbon residential project.
It is clear that municipal zoning policies (or in the Squamish First Nation’s case, a lack of them) can be a key determinant of housing accessibility, affordability, and sustainability. While relaxing zoning rules can play a huge part in improving housing access and carbon footprints in cities, these policies are not silver bullets. Local and regional governments should intervene to correct existing market failures.
For instance, cities should consider how to incorporate inclusionary zoning and social housing options for homeless and low-income residents. Provincial and federal governments alike should provide financial assistance to support transitions to renewable energy and further incentivize the adoption of greener building materials. Additionally, infrastructure funding for local governments can be better tied to the community’s progress in building more homes — especially the construction of multi-unit dwellings in larger population centres.
These interventions can compliment policies that increase housing density, but it is important to note that they cannot offer the potential of upzoning on their own. Relaxing exclusionary zoning rules can reduce urban sprawl, encourage transit-oriented development, and promote sustainable construction. Cities should consider throwing away their yellowbelts if they want to go green.
