We used to worry about energy efficiency. But over the past few years, we have been writing about sufficiency, suggesting that making things more efficient is not enough—we have to ask ourselves what we really need. Sufficiency is defined by Samuel Alexander, co-director of the Simplicity Institute, as:

Sufficiency is a hard sell. We have been writing forever that we should live in smaller spaces, in walkable neighborhoods where you can bike instead of drive. The reality is our posts on Teslas are more popular. But in a world where our problem isn’t energy—we have lots of gas and coal!—but carbon emissions, the concept of sufficiency becomes even more important.

Yamina Saheb is an energy analyst and lead author for the Intergovernmental Panel on Climate Change (IPCC). She writes in Buildings & Cities that sufficiency should be first. Treehugger has called for this before in our buildings and in our lifestyles, but Saheb is more rigorously academic and focuses on buildings. Like Treehugger, she worries that focusing on energy efficiency isn’t enough. She writes:

Saheb defines sufficiency as “a set of policy measures and daily practices which avoid the demand for energy, materials, land, water, and other natural resources, while delivering wellbeing for all within planetary boundaries.” She says there are two boundaries: the upper being the carbon budget or ceiling and the lower being a decent standard of living. Sufficiency measures in buildings include:

  • Optimizing the use of buildingsRepurposing unused existing onesPrioritizing multi-family homes over single-family buildingsAdjusting the size of buildings to the evolving needs of households by downsizing dwellings

Saheb calls for a lot more cohousing strategies, cooperative housing, and eco-villages where people have less floor space per capita because they share resources such as laundry, dining rooms, and guest rooms. She writes: “As a consequence, the consumption of resources including energy, materials, water and electricity is reduced leading to a reduction of both embodied and operational emissions. Less space will also result in less appliances and equipment and alter preferences towards smaller ones.”

Saheb concludes by describing the SER framework that combines sufficiency, efficiency, and renewables.

Sufficiency remains a hard sell. Seattle-based architect Michael Eliason recently tweeted this plan of an apartment that rents for half the price of a three-bedroom in North America, and there was immediate shock at the sight of one bathroom for three bedrooms. It turns out there is another toilet and sink on the lower level under the stairs, but everyone has come to expect two full baths and the two-piece. Smaller appliances might be sufficient, but in North America, even tiny homes on wheels have 30-inch wide fridges and stoves and 24-inch wide dishwashers.

Saheb calls for more cohousing strategies, but as “Happy City: Transforming Our Lives Through Urban Design” author Charles Montgomery recently found out in Vancouver, they are illegal almost everywhere on a continent that favors single-family sprawl.

Small cars and bicycles might be a lot more popular and sufficient for many, but people are scared off the roads by all the giant pickups and SUVs that now dominate and intimidate.

Saheb concludes: “Overall, the unequivocal role of human activities in global warming is unlikely to be reduced unless sufficiency is made a primary principle in climate mitigation scenarios and policies.”

But nobody thinks about sufficiency. Nobody is asking: What is enough? How much space? How much stuff should everyone have when every square foot of space—every pound of stuff—has a big price in embodied and operating carbon?

Alexander has written:

This is why we have to get serious about sufficiency. Enough already.