Economic rough spots can be driving forces for change. In the 1970s, skyrocketing fuel costs forced car makers to increase mileage and builders to tighten homes and increase insulation to save energy. Cost was the major driver, but the overall effects on the environment were inextricably intertwined. Better car mileage and less electricity and natural gas consumption conserved natural resources and minimized pollution.
In the ensuing decades, the push to lessen the impact of buildings on the environment continued to grow, culminating in the sustainability movement. The terms “sustainable” and “sustainability” are subject to varying definitions, and these definitions are continuing to evolve. The National Roofing Contractors Association (NRCA) defines a “sustainable building” this way: “A building that provides the specified building performance requirements while minimizing disturbance to and improving the functioning of local, regional and global ecosystems both during and after specified service life. A sustainable building optimizes efficiencies in resource management and operational performance and minimizes risks to human health and the environment.”