This work will focus on investment decision-making. This has typically been modelled as economically rational, tempered by a number of barriers. However, empirical work questions the adequacy of this approach, particularly at the point of end use (Wilson and Dowlatabadi 2007; Cooremans 2009; Banks et al. 2012), but also in supply (Gross 2007). We will build on these theoretical understandings of decision-making using recent analysis from both previous UKERC research (Rosenow and Eyre 2013) and elsewhere (Fawcett et al. 2013) to create a fuller inter-disciplinary description of decision-making around energy investments, specifically with respect to households and organisational low-carbon investment.