Green Roofs for a Greener Future: An In-Depth Look at Increasing Building Efficiency at UMass Amherst

UMass Amherst has a goal to meet a carbon net-zero goal by 2030. To reach this goal, UMass will need to address sources of energy inefficiency. Energy inefficiency is important to investigate in its biggest consumer of energy, heating and cooling buildings, about 34% of each building’s energy use. The campus’ older buildings are largely inefficient, losing about 20% of their heat and cooled air through the roofs. Building inefficiency wastes a considerable amount of energy and necessitates that the university produces and use more energy, thereby CO2. Green roofs take advantage of a living roof’s natural capacity to heat and cool through improved insulation and evapotranspiration, which provides increased performance in solar panels to further improve emission reductions in older buildings. Older buildings provide an opportunity to utilize valuable space and improve efficiency while avoiding the waste associated with tearing down old buildings to be replaced with new structures built to higher standards. We have buildings on campus that could be retrofitted with green roofs, as they thrive on buildings with lower heights and more surface area. In a model using the Hampden Art Gallery, we found that a green roof would pay itself off in ~11.4 years and had a net present value of over $3 million if left in place for 50 years, even accounting for maintenance. In total, we have estimated that retrofitting our campus with green roofs has the potential to prevent the equivalent of 7467.8 Mt CO2 emissions per year. Green roofs offer both energy reduction and environmental benefits, and retrofitting is the most cost-effective and practical use of our time and funds to meet our carbon mitigation goal.