The earth’s average temperature has risen by about 1.1°C (2°F) since the beginning of the Industrial Revolution. This increase has been caused mainly by human activities, especially the burning of fossil fuels, which release carbon dioxide (CO₂) and other heat-trapping greenhouse gases into the atmosphere. The warming that has already occurred has increased the frequency and intensity of heat waves, droughts, floods, and tropical storms. It has also led to rising sea levels and larger, more destructive wildfires. According to the Intergovernmental Panel on Climate Change, even worse disruption can be avoided by keeping total warming below 1.5°C (2.7°F). To do this, we will need to cut carbon emissions in half by 2030.

While carbon has become a buzzword used to quantify climate impacts, the term is shorthand for CO₂ and other greenhouse gases (GHGs). The terms low carbon and decarbonization refer to lowering GHG emissions. The construction and operation of buildings accounts for nearly 40% of global GHG emissions. This figure includes operational emissions, which are the GHGs that buildings (both new and existing) emit while in use, and upfront emissions—those released during the extraction, manufacturing, transportation, and assembly of building materials. Building codes like the IECC and certifications like the EPA’s Energy Star and the DOE’s Zero Energy Ready Home have focused on reducing operational emissions and energy consumption. But reducing upfront emissions, which occur before a building is occupied, is also critical to achieving the large, rapid cuts in GHG emissions needed to stay below the 1.5°C threshold.

The need to tackle upfront emissions comes at a time when the building industry is already struggling with labor shortages, material costs, and economic uncertainty. But there is some good news. Free software tools can help architects and builders calculate a project’s upfront emissions. These tools reveal…