Energy-saving technologies' applicability to making cities more environmentally sustainable can be strongly influenced by the city's form, building uses and their density pattern. Technological developments have clearly shown specific urban forms to be more conducive to installing certain mitigation technologies. In this study, the capacity for implementation and impacts on energy savings and subsequent greenhouse gas (GHG) reduction potential of mitigation technologies such as photovoltaic cells (PV) and combined heat and power (CHP) technologies were analysed with respect to three potential urban forms (high density centralised, medium density averaged and low density decentralized) for Utsunomiya City, Japan. Given current building use patterns, scenarios for 2030 and 2050, showed the medium density averaged form, which benefits from both PV and CHP technologies, to outperform the other forms, resulting in an energy savings and GHG reduction potential of 27.6% in 2030 and 67.6% in 2050. Interestingly, GHG reduction in 2050 was primarily attributable to PV, while CHP technology had the greater influence in 2030. Despite the limitation of the analysis, the study provides a useful insight, highlighting the relationship between urban forms and GHG reduction potential by two energy-saving technologies. (C) 2009 Elsevier Ltd. All rights reserved.