Evaluating the impact of operating energy reduction measures on embodied energy

Annually, 48% of the global energy is used by buildings in their construction, operation, and maintenance, causing significant damage to the environment due to the resulting greenhouse gas emissions. During their life cycles, buildings use energy in the form of embodied energy (EE) and operating energy (OE). In a conventional building, EE accounts for 10-20% of a building's life cycle energy (LCE), while OE accounts for 80-90%. As a result, the building sector has taken several measures to reduce OE in buildings. These OE reducing measures fail to account for the subsequent increase in EE and might cause an increase in the building's overall LCE. A systematic review of the literature shows limited research that comprehensively evaluates the impact of design measures aimed at OE reduction on EE for different construction assemblies. In this study, we quantify and compare trade-offs on EE demand, caused by OE reduction measures for eight different building wall assemblies across four climatic zones within the United States. The EE and OE demands of the ASHRAE 90.1-2016 benchmark model and its variations were computed using Tally (TM) and Autodesk (R) Green Building Studio (R) (GBS), respectively. The results helped us determine the EE factor (EE spent per unit of OE savings) for different OE reduction measures. Although the calculated EE factors vary across different climatic zones and construction assemblies, these factors show significant EE costs for different OE reduction measures. This knowledge could help inform the design of evolutionary and deep/machine learning-based algorithms to assess and optimize building energy use. (C) 2020 Elsevier B.V. All rights reserved.