Using data from the German Socio-Economic Panel (GSOEP), we show that nearly 50% of all carbon emissions caused by private transportation and building operations in Germany can be explained by structural determinants that go hand in hand with infrastructural peculiarities in rural and urban residential areas. Taking the theoretical background of building physics, allometry and increasing returns to scale as a vantage point, this paper analyses the effects of physical concentration – e.g. apartment buildings versus bungalows – and social compactness – e.g. multigenerational versus single households. In contrast to related studies, this perspective reveals that social and physical concentration tend to counteract each other and thus clarifies the intricate interactions between household structure, different infrastructural environments and carbon emissions. A supplementary finding is that the spatial distribution of fuel types plays a large role in explaining lower carbon emissions in urban settlements. This leads us to the conclusion that environmental policy should foster physical concentration in rural and social concentration in urban infrastructural environments. Copyright © 2012 John Wiley & Sons, Ltd and ERP Environment.