A hybrid database of embodied environmental flow coefficients for HVAC distribution systems

Efforts to reduce the environmental impacts associated with the operation of heating, ventilation and air conditioning (HVAC) systems are typically centred around improving their operational efficiencies and using low emission refrigerants. As a result of these developments, the contribution of the raw material extraction, transportation and production of these systems have become increasingly important from a life cycle perspective. However, the embodied environmental effects of HVAC systems are typically excluded from building-level life cycle assessment studies due to their complexity in terms of the materials and supply chain processes. In this study, a database of embodied environmental flow coefficients for standardised HVAC distribution system components used in the Australian construction sector has been developed, addressing the lack of data required to reliably and comprehensively assess the embodied environmental effects of HVAC systems. Coefficients for three embodied environmental flows, namely, energy, greenhouse gas emissions and water, have been quantified at the component-level using a hybrid life cycle inventory approach, which combines process and input–output data. Using a retail building case study, the useability of the database was demonstrated. The results show that the database covered 81.2% by mass of the whole distribution system, with the remaining components being unaccounted for due to their non-standard sizes. The quantified embodied environmental flows were also found to be at the higher end of existing benchmarks for building services systems, which is attributed to the choice of the comprehensive life cycle inventory approach used. Future research is recommended to further enhance the comprehensiveness of the database by incorporating a greater range of standardised components and by developing methods to account for non-standardised components.