The impact of urban compactness on energy-related greenhouse gas emissions across EU member states: Population density vs physical compactness

It remains a matter of debate whether compact urban development can be a sustainable approach to mitigating greenhouse gas (GHG) emissions, although the compact city theory and GHG emissions have both gained increasing attention. The present study explored the relationship between urban compactness and energy-related per capita GHG emissions among different countries using panel data models. To obtain the energy-related GHG emissions, the GHGs emitted by the energy sector were calculated on a per capita basis according to the “2006 IPCC guidelines for national GHG inventories”. Urban compactness was assessed by two indicators, namely population density and the compactness index, of which the latter measures the overall physical compactness of urban land patches. The case study of the 28 EU member countries during 2000–2012 demonstrated that the two indicators did not correlate with each other and they affected energy-related per capita GHG emissions in contrasting ways. That is to say, population density and the overall physical compactness of urban land patches exerted significant negative and positive influences on energy-related per capita GHG emissions, respectively. These findings imply that high population density, mixed-use urban development with a lower degree of physical compactness is advisable in terms of reducing energy footprints and mitigating GHG emissions. However, consideration should also be given to maintaining a balance between effectively reducing GHG emissions and preventing disadvantages associated with high-density urban development in future urban planning practices.