What’s the future of sustainability for Northeastern University? Balancing energy efficiency with embodied carbon. 

Carbon accounting measures emissions into the Earth’s biosphere of gasses like carbon dioxide, methane, and nitrous oxide. When you think about energy and the environmental impact of a building, most focus on whether a building is energy efficient. But energy efficiency is only one half of the energy pie. The other share is the amount of energy—the embodied carbon—it takes to create, transport, and utilize materials to build the building. Making high-performance design decisions requires a delicate balancing act between carbon emissions and energy savings. 

When Northeastern University was ready to modernize Speare Hall, a four-story traditional style residence hall, the Green Lab jumped in to conduct energy studies. The team wondered would it be better to use less embodied carbon by simply repairing the Hall’s tower, or would using new cladding on the exterior improve the thermal properties of the envelope enough to result in significant energy savings, offsetting the carbon emissions created by adding new material? 

Based on the architectural model, the Green Lab calculated the mass of every element of the building’s exterior. Then, they used those numbers to determine the environmental impact of CO2 emissions for repairs versus the new cladding. The Team  discovered that the new cladding would require a 2% greater embodied carbon investment than the repairs but would also significantly improve the thermal comfort in the building, realizing a 10% operational emissions savings over the 40-year life of the building envelope. The impact of Speare Hall’s envelope modernization is the equivalent of taking 670 cars off the road. That’s some serious carbon-savings pie!