Car and Home Designs Prioritizing Sufficiency Can Drastically Cut Emissions

Small cars and small homes could save big.

Small car in front of multifamily housing
Small car in front of multifamily housing.

Alexander Spatari / Getty Images

In our search for ways to reduce our carbon emissions, a favorite word on Treehugger is sufficiency— the concept of not using any more than you need. (A recent addition to our vocabulary was ephemeralization—doing more things with less stuff.) However, we never really could put a number on sufficiency like you can when you talk about efficiency. Now, a study published in Nature Communications does exactly that.

The authors, Edgar Hertwich and Stefan Pauliuk, described in Carbon Brief how designing and building lighter and smaller buildings and cars could reduce the carbon emissions in those sectors by up to one-third. They call this process dematerialization, defined as: "A reduction in the quantity of materials used to serve the production and consumption needs of our societies. Dematerialization is an input-oriented strategy, which, in contrast to traditional ‘end-of-pipe’ measures, intends to tackle environmental problems at their source."

From the study:

"We present a global-scale analysis of material efficiency for passenger vehicles and residential buildings. We estimate future changes in material flows and energy use due to increased yields, light design, material substitution, extended service life, and increased service efficiency, reuse, and recycling. Together, these strategies can reduce cumulative global GHG emissions until 2050 by 20–52 Gt CO2-eq (residential buildings) and 13–26 Gt CO2e-eq (passenger vehicles), depending on policy assumptions. Next to energy efficiency and low-carbon energy supply, material efficiency is the third pillar of deep decarbonization for these sectors."

Those are serious gigatonnes and what we call upfront carbon emissions—it happens before you move into the home or drive the car off the lot. The authors use the term "material efficiency," or ME. We have used the term "design efficiency" and sufficiency to mean the same thing: using as little material as possible to do the same job.

In housing, strategies include:

  • Reducing unit size by up to 20%, which can often be done simply by opting for good design and wasting less space.
  • Building multi-unit housing instead of single-family, where, as Paul Simon sang about the benefits of efficiency, one man's ceiling is another man's floor.
  • Building out of timber instead of concrete and masonry because of the lower carbon emissions.

With cars, the numbers were based on strategies including:

  • Significantly fewer cars with more intensive use due to car sharing
  • "Lightweighting," a substitution of heavier materials, such as steel, with lighter materials, such as aluminum, increasing a vehicle's fuel economy. 
  • Downsizing, reducing the size and the weight of cars, noting that This may happen automatically as a result of car sharing, as rental cars can be trip-appropriate compared to purchased cars, which must be all-purpose.
  • Better recycling and remanufacturing.

Of course, we would add the impact of bikes, e-bikes, and transit. The professors also show that "cutting overall demand for new products and therefore materials are at least as important as increasing recycling, especially for establishing co-benefits between circular economy and climate change mitigation." All of this is backed up with a vast database, backing up their numbers.

They conclude:

"The research also shows that, in absolute terms, emissions cuts from dematerialisation in developing countries are much larger than those in industrialised countries. Realising some of these gains is perhaps not trivial in terms of policy innovations, but it requires no technical breakthroughs. In fact, the technologies are all in place, and we could begin making the gains identified by our research almost at once."

Dematerialization. Ephemeralization. Sufficiency. Material efficiency. Design efficiency. We are all saying the same things: Make less stuff, make it better, and make it last. No new tech is required. And as this study shows, it can save us some serious gigatonnes of carbon dioxide.