This paper reports on the use of a new method to evaluate the optimal insulation thickness according to life cycle assessment (LCA) in pipe insulation applications. In this study, the optimum insulation thickness in the pipes is analysed based on two different methods (life cycle assessment - LCA and life cycle cost - LCC) used to determine the optimum insulation thickness for the environmental impact reduction of pipe insulation. Thus, the LCC analysis is used to evaluate the accuracy of this new method; data are collected from the insulation and energy markets, and the results are compared. The effects on the environmental and cost parameters of insulation thickness are also discussed in detail. The results indicate that the total environmental impacts are almost the same values in both methods, whilst the optimum insulation thickness is overestimated by up to eight-fold in the LCA analysis. As a result, the LCC analysis can be used in the determination of the optimum insulation thickness; however, it must be supported with the LCA analysis for environmental impact reduction. (C) 2016 Elsevier Ltd. All rights reserved.