Many cities are likely to expand in the coming decades and this expansion will probably include low-density neighbourhoods. There is an increasing pressure on cities worldwide to accommodate an increasing population. It is therefore crucial to assess the energy demand and related greenhouse gas emissions implications of such development. This paper uses a representative low-density neighbourhood in Melbourne, Australia, assesses its energy consumption and greenhouse gas emissions over 100 years and investigates various scenarios related to house size, transport technology, housing typology and the temporal evolution of parameters. Results show that the energy required to produce and replace building materials and infrastructures constitutes 26.9% of the total energy consumption, while operational and transport requirements represent 39.4% and 33.7% respectively. One of the analysed scenarios reveals that replacing half of the built area of the suburb with apartment buildings reduces the total energy consumption per capita by 19.6%, compared to a typical single storey detached house layout. Regardless of the uncertainty in the data, the main conclusion is that each of the embodied, operational and transport energy demand and associated greenhouse gas emissions can be reduced in order to improve the overall environmental performance of new urban neighbourhoods.