Life cycle embodied, operational and mobility-related energy and greenhouse gas emissions analysis of a green development in Melbourne, Australia

At least 40% of total greenhouse gas emissions are related to the built environment, mostly because of energy coming from fossil fuels. In response, developments with an improved energy efficiency (e.g. so-called ‘green’ or ‘net-zero energy’ developments) have been built. Despite reductions in operational energy use in ‘green’ developments, previous studies have identified trade-offs in terms of embodied energy in construction materials and sometimes transport energy associated with the mobility of building users. This research reconsiders the evaluation of green environmental claims through a life cycle approach. A multi-scale life cycle energy assessment software tool is employed to quantify the energy use and greenhouse gas emissions of a case study medium-scale green development in Melbourne, Australia over 50 years. Results show that the total life cycle energy use and greenhouse gas emissions of the development are 1,492 TJ (2,688 GJ per capita and 107 GJ/m2 of GFA) and 81 ktCO2-e (146 tCO2-e per capita and 6 tCO2-e/m2 of GFA), respectively, compared to 2,220 TJ (4,001 GJ per capita and 159 GJ/m2 of GFA) and 177 ktCO2-e (318 tCO2-e per capita and 13 tCO2-e/m2 of GFA) for a business-as-usual development with the same geometry. In fact, each of the embodied, operational and transport energy requirements represents an important contribution to the life cycle energy: 31%, 35% and 34%, respectively. Therefore, all life cycle stages and scales of the built environment are relevant to the overall energy and greenhouse gas emissions performance of green developments.