According to the latest annual figures from the U.S Energy Information Administration (EIA), the residential and commercial sectors—or buildings sector—accounted for 35 percent of total U.S. energy-related carbon dioxide (CO2) emissions in 2019. (No longer 40 percent as commonly purported.)

In fact, due to the aggregate effect of a variety of factors, the total annual energy-related CO2 emissions in the U.S. dropped across all sectors to the effect of 151 million metric tons of carbon (or 3 percent).

The buildings sector accounted for 66 percent of the total decrease energy-related U.S. CO2 emissions: 35 percent from the residential sector and 31 percent from the commercial sector. 

Much of the decrease is attribute to the electric power sector’s decrease in carbon intensity of generation as well as increased energy performance of our building stock. 


Continued carbon reductions require adapting our existing buildings 

This is evidence that the building design and construction industry is making progress toward decreasing the operational carbon contribution from our building stock. We should celebrate and share knowledge from our accomplishments with new high-performance projects.

However, there is an elephant in the room: out immense, aging, inefficient building stock.

According to Ed Mazria, FAIA, and his nonprofit Architecture 2030, in addition to the unprecedented growth in the global building sector, nearly two-thirds of the building area that exist today will still exist in 2050.

The EIA's 2018 Commercial Building Energy Consumption Survey (CBECS), tends to support this data—at least for the commercial sector. According to the latest edition of the survey:

  • Buildings built between 1960 and 1999 account for 54 percent of both number of building and of floorspace.
  • One-quarter of buildings (25 percent) were built since 2000, accounting for 29 percent of total floorspace.
  • Buildings built before 1960 represent 21 percent of building but only 17 percent of total floorspace.
  • The median year of construction is 1982.

Therefore, any transition to low-carbon/carbon neutral built environment must address both new construction and existing buildings. 


Figure: Share of number of U.S. buildings and floorspace by year constructed.
Data source: U.S. Energy Information Administration.
Figure courtesy of author. 



Market trends point to increasing opportunity with existing building

According to the American Institute of Architect's (AIA) Firm Survey Report 2020, an emerging emphasis on greening our building stock has contributed to an increased share of design activity focused on retrofitting and improving existing facilities. In fact, the percentage of firm building design billings derived from projects related to adapting existing buildings has increased roughly 1 percent per year since 2005 to 49.3 percent in 2019.

Additionally, the devastating COVID-19 crisis is forcing the commercial real estate industry to quickly innovate and adapt to a post-pandemic market. Facility re-entry planning may introduce myriad opportunities to fold in high-performance project goals to better ensure long-term preparedness.

As in so many other facets of the economy, the pandemic appears to be functioning as an accelerant for critical pre-existing trends. A holistic approach to adapting our existing building stock to make it more resilient will require us to integrate the emerging priorities of health, wellness, safety, and high-performance.