Study: Retrofitting Old Buildings Has Lower Total Carbon Footprint Than New Construction

A study of embodied carbon — carbon emissions produced over the entire life cycle of a product — produced by buildings found that retrofitting existing buildings produces significantly lower emissions over the entire life cycle, reports Nish Amarnath in Smart Cities Dive.

As a result, demolishing an existing building to construct a new one makes little sense from an environmental perspective, even if that new building is more energy efficient, according to the research note.

According to Amarnath, understanding the total carbon impacts of a building is difficult in the United States due to a lack of a comprehensive building inventory and building-level data as well as no clear benchmarks for assessing embodied carbon.

The researchers used data from over 1 million Chicago buildings to show that “increasing the average lifespan of buildings from 50 years to 75 or 80 years and reducing building size by 20% can cut their overall carbon emissions by two-thirds.” Buildings with masonry structures and walls have the highest emissions over their life cycle, while buildings with wooden structural elements and shingled roofs have the lowest emissions.

The researchers acknowledge the challenges of retrofitting older buildings, noting that some energy efficiency upgrades can also increase the overall production of embodied carbon. “If the goal is to enhance energy efficiency and achieve long-term cost savings, upgrading the HVAC system and improving the building envelope should be prioritized.”