Life Cycle Assessment Framework for Embodied Environmental Impacts of Building Construction Systems

This paper develops a life cycle assessment framework for embodied environmental impacts of building construction systems. The framework is intended to be used early in the design stage to assist decision making in identifying sources of higher embodied impacts and in selecting sustainable design alternatives. The framework covers commonly used building construction systems such as reinforced concrete construction (RCC), hot-rolled steel construction (HRS), and light steel construction (LSC). The system boundary is defined for the framework from cradle-to-grave plus recycling and reuse possibilities. Building Information Modeling (BIM) and life cycle assessment are integrated in the developed framework to evaluate life cycle embodied energy and embodied greenhouse emissions of design options. The life cycle inventory data used to develop the framework were extracted from BIM models for the building material quantities, verified Environmental Product Declarations (EPD) for the material production stage, and the design of construction operations for the construction and end-of-life stages. Application of the developed framework to a case study of a university building revealed the following results. The material production stage had the highest contribution to embodied impacts, reaching about 90%. Compared with the conventional RCC construction system, the HRS construction system had 41% more life cycle embodied energy, while the LSC construction system had 34% less life cycle embodied energy. When each system was credited with the net benefits resulting from possible recycling/reuse beyond building life, the HRS construction system had 10% less life cycle embodied energy, while the LSC construction system had 68% less life cycle embodied energy. Similarly, the HRS construction system had 29% less life cycle greenhouse gas (GHG) emissions, while the LSC construction system had 62% less life cycle GHG emissions. Sustainability assessment results showed that the RCC construction system received zero Leadership in Energy and Environmental Design (LEED) credit points, the HRS construction system received three LEED credit points, while the LSC construction system received five LEED credit points.