In the domestic heating sector a number of different mathematical models are used to evaluate the economic viability thermal retrofit measures. Currently, however, none of these models incorporate the effect of furl price elasticity of demand. This paper offers a method for incorporating a factor for fuel price elasticity into models for assessing the net present value and payback time of thermal retrofits of existing homes. A set of working equations is developed, and empirically tested in a case study, a housing estate retrofit project in Ludwigshafen, Germany. The value used in these equations for year-on-year price elasticity, -0.476, is derived from further empirical studies. The inclusion of price elasticity id found to lower the net present value by 14-24% and lengthen the payback time by 5 years in some cases, and hundreds of years in others. It is also shows CO2 saved over the technical lifetime of the retrofit measures to be 15-24% lower than anticipated. These findings have implications for government policy and investment decisions of business, private household and housing providers. (c) 2012 Elsevier B.V. All rights reserved.