Life Cycle Thinking

Together, transportation and building operation accounts for over two-thirds of energy consumption in the United States. The design of the supporting infrastructure —primarily roadway pavements, and residential and commercial buildings — can play a significant role in improving the sustainability of these operations. As we develop strategies to reach sustainability goals, it is vital that we adopt methodologies that use a life-cycle perspective to evaluate impacts and use that knowledge to create a strategic path moving forward. Life cycle analysis methodologies exist for both environmental and economic impacts, known respectively as life-cycle assessment  (LCA) and life cycle cost analysis (LCCA). These methodologies enable engineers, designers, and decision makers to better understand the impacts of infrastructure and the opportunities that exist to reduce them.

Life cycle assessment considers all life-cycle phases, from initial construction to demolition. System boundaries are drawn to capture each mechanism by which pavements and buildings impact the environment. These boundaries not only include the materials and activities needed to construct the infrastructure, but also the operation, maintenance, and end of life phases of the life cycle. For pavements, this means accounting for traffic delay, lighting demand, future maintenance, and other phases and components that occur after the pavement is initially put in service. Likewise, the building life cycle includes the fuel and electricity demands needed for heating, cooling, and lighting operations.  Drawing upon the best available data, the environmental impacts from each element of the life cycle can be quantified.

Similar to LCA, the LCCA approach seeks to quantify the economic impacts over the infrastructure life cycle by identifying the costs during each phase. Because LCCA accounts for future maintenance and operational activities, the results are more comprehensive and can provide a more accurate portrayal of the actual economic burden associated with infrastructure than the initial costs alone, which are often a poor predictor of life cycle economic costs. Poorly insulated and leaky residential construction leads to high annual energy costs, which can result in substantially higher life cycle costs. Likewise, roadway closures cause traffic congestion, which leads to higher costs for road users. Accompanying the environmental impacts from LCA with the economic impacts from LCCA creates a marked advancement in the utility of the assessment as a whole, providing the necessary economic context to implement those solutions into the marketplace.