The Great Green City
The most environmentally friendly thing a city can be is a great city. Today, the biggest threat to the environment is climate change caused by greenhouse gasses, mostly carbon dioxide. Dense, urban, walkable cities emit far less CO2 than places that are car dependent. To make our communities environmentally friendly, we must pursue a building boom equivalent to what America saw after World War II, on the exact same land.
As cities grew and became dirtier during the Industrial Revolution, people started to bring nature into the city. There was a concerted effort to separate industrial uses from residential and recreational uses, which we can easily recognize today by looking at any city’s zoning map. Over time, residential and recreational uses were made to look as much like the rural country as possible, as a way to emulate nature within the city. Unfortunately, this lead to cities that are spread out and car dependent, leading to greater environmental harm than if cities that had no nature at all.
Nature in cities is still important. Street trees make streets more walkable by providing shade and protection from cars. Greener cities are also less susceptible to the urban island heat effect. And people need open space and parks for relaxation and recreation. But this type of nature should not be at the expense of creating a dense, urban, walkable community, but in service of that goal.
Twenty-eight percent of all carbon emissions come from transportation. Another 11% comes from heating and cooling buildings. Both of these are dramatically reduced in dense, walkable communities.
Walkable communities, as the name implies, are compact enough that most residents don’t need to use a car to run their day to day errands. Instead, they are able to walk to the store or local restaurants. These communities are also easily served by transit because of their compactness. Transit, in turn, allows people to travel even further without the need for a car. Not only are people able to run day to day errands, but they are able to live their entire daily lives without a car if their home and work are both in walkable neighborhoods connected by transit.
The compactness and density of a place also drives that places resource usage. Counter-intuitively, the more dense a place is, the less resources it uses per person. People use less water due to their smaller yards, they use less gas due to their ability to use transit and the shorter distances they need to drive when the do drive, and they use less natural gas or electricity for heating and cooling their homes. The best insulation any wall can have is an adjoining unit. Sharing a common wall gives that wall a rating of R∞.
Opportunities for creating a Great Green City
After World War II, many communities developed in similar ways. Single family homes were spread across the land, connected by arterial roads that were lined by strip malls. These arterial roads can be transformed into walkable urban spines, if the strip malls can be redeveloped into higher density residential and mixed-use buildings. This building boom is one of the few remaining ethical uses of our carbon budget, along with electrification of the power grid.
A few things need to change in a city’s roadway plans to ensure that its existing arterial roadways can support walkable urbanism. First, more space needs to be dedicated to cyclists and pedestrians. Room for these additional modes of transit can be found by making lanes narrower, which has the added benefit of slowing down cars and making the street safer for all road users.
Second, dedicated rapid transit needs to be built throughout the arterial network. The rapid transit system should be built out incrementally, focusing first on the areas that a community wants to see redeveloped first. The rapid transit can be either bus or rail, so long as permanent improvements are made to separate the rapid transit lanes from the regular travel lanes. This permanent separation ensures that rapid transit is actually rapid, otherwise the buses and trains can’t go any faster than the jammed traffic and people will have no incentive to use the transit, and because it’s permanent the city will see private investment along the transit line because developers and investors will know that the transit will be there for the life of the building.
Once these public improvements are planned and start to be implemented, developers will start to be interested in the opportunity to redevelop the strip retail flanking the arterial streets. Before developers develop their interest in an area, the city must create some guidelines that articulate what the community would like to see built along these arterials. These guidelines can be in the form of a specific plan, form-based code, or simply design guidelines depending on how strictly the city wants to hold developers to the guidelines.
These guidelines will help developers understand what the community wants to see built and provide some surety that whatever new development they propose will be acceptable and be approved by the city. From a developer’s point of view, being confident that something will be approved is as valuable as a cash subsidy to a project.
To create a great green city that is walkable, the most important part of any new development is the area between the street and the front of the building, and the building facade from the ground to about halfway up the second story. This triangle is the only part of the streetscape that pedestrians notice, and therefore the only part of the streetscape that needs extra attention to make for a pedestrian friendly street.
The simple act of creating a walkable street network in a transit served neighborhood goes a long way towards creating a Great Green City. Resource usage in these neighborhoods is lower than in a traditional single-family neighborhood, car usage and the resultant carbon emissions is decreased, street trees help clean the air and reduce the urban heat island effect, and as a result of all of this these neighborhoods are not only better for the environment but are healthier places to live.
[Note: This is one article in a longer series on climate change, part of a larger look at how local communities can address global issues related to climate change, housing affordability, the local economy, the fiscal solvency of cities, and public health.]
