Transport and Building Emissions Are Not Separate—They Are 'Built Environment Emissions'

We have to stop putting everything into separate silos, it all connects.

View of Levittown, New York
Bettmann Archive / Getty Images

During Transportation Day at the 2021 United Nations Climate Change Conference (COP26), all the discussion was about electric cars. There was barely a peep about bikes or that much more efficient electric vehicle (EV), the e-bike. Treehugger reported on a letter from 64 bicycle organizations complaining that bikes could be part of the solution to the problem of carbon emissions, and much more quickly than trying to convert the fleet of gas cars to electric. They made a number of suggestions in their letter for fixing this, that all had to do with bike infrastructure, incentives, and "mobility solutions for a multimodal ecosystem capable of covering all user needs without relying on a private car."

Emissions by sector

Architecture 2030

But the real problem comes down to the idea of having a transportation day at all, of separating transportation from other sources of emissions. Everybody does this, with neat pie charts showing that buildings are responsible for 39% and transport 23%, or some variation of this. But they are not. They are both what I will call "Built Environment Emissions," picking up on the work of Built Environment Declares, which writes that the carbon story goes way beyond just buildings:

"If we are to reduce and eventually reverse the environmental damage we are causing, we will need to re-imagine our buildings, cities and infrastructures as indivisible components of a larger, constantly regenerating and self-sustaining system."
construction share

International Energy Agency

Some of these graphs are more detailed than others, but end up in the same place: Transport is unrelated to building and construction. When researching my book, "Living the 1.5 Degree Lifestyle," my sources listed housing and mobility as two separate topics, two separate sources of carbon emissions. But in fact, they are deeply connected. I wrote:

"Years ago, the environmental thinker Alex Steffen wrote a brilliant article titled “My Other Car Is a Bright Green City” that profoundly influenced me. he wrote: “There is a direct relationship between the kinds of places we live, the transportation choices we have, and how much we drive. The best car-related innovation we have is not to improve the car but eliminate the need to drive it everywhere we go.”

This may seem obvious, but people continue to think of transportation as being separate from the built form but they are not. Transportation consultant Jarrett Walker nailed it in a tweet: “Land use and transportation are the same thing described in different languages.”

As I wrote in my book:

"It is not a chicken-and-egg, a which came first thing. It is a single entity or system that has evolved and expanded over the years through the changes in the form of energy available, and in particular the ever-increasing availability and reduction in the cost of fossil fuels."

In the conclusion to my book, I reiterated this:

"How we live and how we get around are not two separate issues; they are two sides of the same coin, the same thing in different languages. It’s much easier to live a low-carbon life if you live in a place designed before the car took over, be it a small town or an older city. But for the people who don’t do that, the problems are immense."

This is why whenever I write about the benefits of e-bikes I get comments like: "It would be nice if everyone could super-lightweight their ride right away but not everybody works in an office nearby with ample shopping also nearby. It requires work to make a car-optional society."

Indeed it does. That's why we have to stop looking at transportation as a separate category from buildings and have to change our zoning and building regulations to promote the kind of development that makes being car-optional easier. The first change would be to eliminate restrictions on building densities. As American futurist Alex Steffen wrote:

"We know that density reduces driving. We know that we're capable of building really dense new neighborhoods and even of using good design, infill development and infrastructure investments to transform existing medium-low density neighborhoods into walkable compact communities... It is within our power to go much farther: to build whole metropolitan regions where the vast majority of residents live in communities that eliminate the need for daily driving and make it possible for many people to live without private cars altogether."
Steel uses


The illogic of separating transportation from buildings is everywhere. take steel; its production is responsible for 7% of carbon emissions. Fully half of it is going into tall buildings that house people working, and 13% of it is going into cars to drive people from their homes to the tall buildings. Concrete is probably a similar story.

Sankey drawing 2019

Lawrence Livermore National Laboratory / Department of energy

You can look at it another way with the Livermore Lab's Sankey Graph showing where energy in the U.S. goes. Using pre-pandemic 2019 numbers, in which the total consumption conveniently hits 100.2 quadrillion BTUs, buildings are sucking up 21 quads directly, transportation 28.2, and let's say 63% of industrial is going into making buildings and cars, the same ratio as the steel industry. That totals 67.1 quads, roughly 67% of all energy used in the U.S.

Emissions by sector

Our World in Data

So if instead of looking at every sector on its own, if you take a consumption-based view of where all this stuff goes into, and where all the carbon emissions come from, the vast majority of emissions from energy are coming from operating our buildings, driving our cars, or making the materials to build our buildings and our cars. You almost end up with agriculture and aviation as being the two largest categories that don't fit into Built Environment Emissions. By this standard, Built Environment Emissions might be as high as 75%.

It is an issue that comes up again and again when you look at the world through the lens of production, rather than consumption. Outside of governments buying F35s and aircraft carriers, all of this energy use and greenhouse gas emissions are coming from making stuff that people buy. If they don't have to buy it, then consumption and emissions go down. If people had available options, they might change their lifestyle choices. The biggest problem is that they often do not have options.

15-minute city

Courtesy of Paris en Commun

There are ways to fix this. If we all lived in Professor Carlos Moreno's 15-minute city, this would not be a problem. The C40 Mayors noted this is a matter of zoning and building design.

"The presence of nearby amenities, such as healthcare, schools, parks, food outlets and restaurants, essential retail and offices, as well as the digitalisation of some services, will enable this transition. In order to achieve this in our cities, we must create a regulatory environment that encourages inclusive zoning, mixed-use development and flexible buildings and spaces."


Other groups, like the Institute for Transportation and Development Policy (ITDP) have proposed a Transit Oriented Development pattern that I thought was misnamed because it also prioritized other forms of transport.

"The TOD Standard sums up the new priorities for contemporary urban development. They reflect a fundamental shift from the old, unsustainable paradigm of car-oriented urbanism toward a new paradigm where urban forms and land uses are closely integrated with efficient, low-impact, and people-oriented urban travel modes: walking, cycling, and transit."

But they also get that this is an issue of land use and urban form, not transportation technology.

It is easy to see why e-cars (I am not calling electric cars EVs anymore because e-bikes are EVs) are such a popular approach with the politicians at COP26. As Carlton Reid notes in Forbes, they are a convenient way of maintaining the status quo. He quotes Lord Tony Berkeley, patron of the United Kingdom's Parliamentary Group on Cycling and Walking:

“Encouraging people to continue to use private vehicles helps perpetuate the kind of thinking that has led us to our problematic car-dominated society. Electric vehicles provide an attractive option because they require little behavior change. The reality is that we all need to make large and wide-ranging changes to our lifestyle."

But making lifestyle changes doesn't have to be hard or unpleasant; if you live in the kind of place where you can walk or bike to shop, it's rather pleasant. I live in a duplex in a "streetcar suburb" in Toronto, designed just before the car took over, and it is all very convenient. This is because of a built environment that encourages travel by bike or foot.

This is why the list of demands presented to COP26 and prepared by the 64 cycling organizations is incomplete. One of their suggestions of "Building synergies with public transport and foster combined mobility solutions for a multimodal ecosystem capable of covering all user needs without relying on a private car" gets close, but they should be sitting down with Architects Declare or the Architects Climate Action Network and add a few more points which could also apply in North America:

  • Ban single-family zoning and permit small multi-family developments everywhere. Change the building codes to make those little buildings easier and more economical to construct.
  • Put a carbon tax on building materials to promote low-carbon construction and the reduction or elimination of underground parking.
  • Eliminate sprawl by legislating that all new development, commercial or residential must be within a 20-minute walking distance of decent transit running dedicated rights of way, essentially Transit-Oriented Development.
  • Ensure that safe and secure bicycle parking is provided in every building.

Those are just a few thoughts about ways to encourage the kind of development that can get people out of cars. It can be a hard sell; even in places that were designed before the car, such as much of London, the drivers are enraged at every Low Traffic Neighborhood. In New York City, they are complaining about losing parking to outdoor dining.

But the main point of this article is that we have to stop talking about transportation emissions as something detached from building emissions. What we design and build determines how we get around (and vice versa) and you cannot separate the two. They are all Built Environment Emissions, and we have to deal with them together.