IPCC Report Outlines How to Create Livable, Sustainable Buildings and Cities

The most notable points are the 5 Cs.

Housing in Vienna.

Lloyd Alter

The latest Intergovernmental Panel on Climate Change (IPCC) Working Group III report on climate change mitigation was more positive than I expected. After reviewing the report, it is clear we have many of the tools we need but aren’t implementing them at the speed and scale necessary to limit warming. I took notes while reading the technical summary and built environment chapters, pulling together some highlights and concepts worth noting. I am calling them the 5 Cs.


15-minute city
A diagram of Carlos Moreno’s 15 Minute City concept.

Paris en Commun

"Urban land use and spatial planning for walkable and co-located densities together with electrification of the urban energy system can hold more benefits for the SDGs than any one of the mitigation options alone."

How blocks, districts, and cities are planned will have a significant effect on carbon emissions. The European Union is already heavily focused on car-free/light, dense, walkable areas and eco-districts with a mix of uses, which is in line with Carlos Moreno’s "15-Minute City" concept.

The report emphasizes policies should prioritize multifamily housing and limit sprawl—both necessary along with a mix of uses to ensure walkability. While there was far less literature on bike-friendly cities than I expected, compact urbanism enabling walking, cycling, and a moderate level of density will be a central role moving forward. It will be interesting to see if any cities in North America decide to lead—or even catch up—on this.

 Carbon Lock-In

Wood Construction

Waugh Thistleton Architects / Daniel Shearing

"Designing for resilient and low-carbon cities today is far easier than retrofitting for risk reduction tomorrow."

Policy plays a large role in avoiding carbon lock-in, with the report specifically pointing out insufficient energy codes and lack of mandates for energetic retrofits that are significant levers. Compact urban form can reduce carbon lock-in, whereas parking mandates and regulations for low-density sprawl increase it significantly. Bio-based and decarbonized construction materials can be beneficial, but there are also associated land-use risks with sourcing and how these materials are used.

 Curbing Car-Centricity

A graph covering transport global GHG emissions trends


"Designing for resilient and low-carbon cities today is far easier than retrofitting for risk reduction tomorrow. As urbanization unfolds, its legacy continues to be the locking-in of emissions and vulnerabilities."

It’s no secret that cars and sprawl are responsible for a significant portion of carbon emissions. There are also a host of negative externalities associated with cars in urban areas, including dementia, asthma, heart disease, and unsafe streets. Solutions can be re-democratizing public right of ways for parks and plazas and prioritizing active mobility and transit. I’m a huge fan of pedestrian zones and car-free eco-districts, and hope we see more of them in North America. The report also featured this graph highlighting how much of an outlier North America is on this issue.


Sponge City Co-Benefits
Sponge City Co-Benefits.


"The multiple co-benefits of mitigation actions are rarely integrated into decision-making processes. So, there is a need to further develop methodologies to quantify and monetise these externalities as well as indicators to facilitate their incorporation in energy planning."

The report plays up many of the co-benefits and synergies of various mitigation strategies. For example, reducing car traffic results in lower noise and air pollution, which are associated with positive health outcomes and increased quality of life.

Sponge cities and blue-green infrastructure are heavily featured, and rightfully so, as they have many co-benefits: mitigating stormwater, carbon sequestration, contributing to more livable cities, increased biodiversity, reducing urban heat island effect and cooling loads, just to name a few. I expect there will be a significant focus on co-benefits in the coming years, especially as they relate to positive public health outcomes and economic multipliers. 


An exterior view of a Baugruppen in Berlin with trees in front of it.
The R-50 Baugruppen in Berlin.

Lloyd Alter

"Cohousing strategies provide users, in both new and existing buildings, a shared space (i.e, for laundry, offices, guest rooms and dining rooms) to complement their private space. Thus, reducing per capita consumption of resources including energy, water and electricity, while offering social benefits such as limiting loneliness of elderly people and single parents."

A pleasant surprise was the endorsement of community-oriented housing like Baugruppen and cohousing, with an explicit nod towards how they increase sufficiency and reduce energy consumption while addressing the loneliness crisis. We’ve been advocates for these forms of housing for over a decade—and this is just another reason they are so appealing.

There is no singular solution to climate mitigation and different cities will require different interventions, with vast differences between developing and established cities. Informal settlements and economies were also acknowledged in the report, as was the need to incorporate Indigenous knowledge.

The report identified barriers to adoption. Knowledge gaps and language barriers exist but can easily be overcome with the right support. Finance is a massive barrier, with a significant mismatch in what and where funding is going, which can exacerbate carbon lock-in. The E.U. has been fairly successful in scaling high-performance product innovation and adoption, in part due to effective research and development coupled with increasingly stringent energy codes. However, that adoption has been slow to non-existent in other countries.

We have the tools and the pathways to meet our climate goals. We need comprehensive leadership, with strong policies and corresponding funding in place. Working rapidly to mitigate climate change will require systemic transformations of our built environments. The resulting interventions will have a knock-on effect with co-benefits, ultimately resulting in more livable and more sustainable cities.

It is also crucial that equity plays a role, as meeting our climate goals is not only an economic and environmental challenge—but ultimately a social one. 

Time is up. We have a lot of work to do. 

View Article Sources
  1. "Climate Change 2022: Mitigation of Climate Change." Intergovernmental Panel on Climate Change, 2022.

  2. Alves, Alida, et al. "Assessing the Co-Benefits of Green-Blue-Grey Infrastructure for Sustainable Urban Flood Risk Management." Journal of Environmental Management, vol. 239, 2019, pp. 244-254., doi:10.1016/j.jenvman.2019.03.036