Embodied Energy Calculation: Method and Guidelines for a Building and its Constituent Materials

Abstract

The sum of all energy embedded in products and processes used in constructing a building is known as embodied energy. According to the literature, the current state of embodied energy research suffers from three major issues. First, there is little agreement on the definition of embodied energy. Second, the existing embodied energy data suffers from variation and are regarded as incomplete and not specific to a product under study. Third, there are various methods for calculating embodied energy with varying levels of completeness and accuracy. According to the literature, the input-output-based hybrid method is the most appropriate method but it needs further improvements. Some of the studies also found a positive and strong correlation between the cost and embodied energy of a building but this correlation needs to be analyzed at a building material or product level. This research addressed the three issues identified by the literature. First, using a rigorous literature survey, it proposed an embodied energy definition, a complete system boundary model, and a set of data collection, embodied energy calculation, and result reporting guidelines. The main goal of proposing the guidelines was to streamline the process of embodied energy calculation to reduce variations in embodied energy data. Second, three improvements were carried out in the current input-output-based hybrid approach, which included process energy data inclusion, human and capital energy integration, and sectorial disaggregation to calculate material-specific embodied energy. Finally, the correlation between the embodied energy and cost and price was analyzed at a material level. The study concluded that an input-output-based hybrid method was the most appropriate method for calculating the embodied energy of a building material in a complete manner. Furthermore, incompleteness in the results of a process-based method was significant (3.3 to 52% of the total). The energy of human labor and capital inputs was up to 15% of the total embodied energy. It was also found that the sectorial disaggregation could provide results specific to a material under study. The results of this study indicated a strong and positive correlation between the embodied energy and cost (and price) of building materials under study.

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Keywords

Embodied energy, Building materials, Life Cycle Energy Assessment, System boundary, Input-output-based hybrid method

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