Optimization and BIM-based lifecycle assessment integration for energy efficiency retrofit of buildings

A retrofit plan for improving the energy efficiency of an existing building can contribute to a sustainable built environment. This study presents a novel framework for integrating mathematical optimization, 6D-Building Information Modeling (BIM), and Life Cycle Assessment to enhance existing buildings' energy efficiency through applying energy retrofit measures. This framework aims to (1) integrate life cycle cost, and environmental impacts analysis (2) identify energy-efficient alternatives for buildings' energy retrofit (3) make the decision-making process straightforward for decision-makers and investors (4) discover the primary energy efficiency agents that impose the most energy waste on existing buildings. This study contributes to the body of knowledge by applying effective retrofit measures and alternative material choice and empowers decision-making by analyzing life cycle cost and environmental impacts of building envelopes by combining mathematical optimization, BIM, and LCA. The BIM energy model compares the cooling and heating loads of the building's components before and after applying retrofitting measures. The results show that inefficient buildings' envelopes and evaporative coolers play a significant role in energy consumption. A developed mathematical optimization model estimates the economic benefits of energy efficiency upgrades to minimize the total life cycle cost of a building during its lifetime. Moreover, it provides an optimum energy retrofitting scenario that leads to reductions of 24%-58.2% in energy consumption. In conclusion, the Life Cycle Assessment Comparison between the building before and after retrofitted measures demonstrates that over 45% of global warming impacts could be reduced in the well-established building.