Optimization of external walls thermal insulation technologies considering costs and time of execution

Buildings constructed several decades ago do not meet the energy efficiency requirements of current legislation and therefore needlessly consume great amounts of energy for heating. Most often their energy performance is improved by applying additional thermal insulation layers on buildings external walls. Research presented in this paper analyses construction technologies of various thermal insulation types and corresponding time needed for work execution and related costs. Economic analysis of proposed thermal insulation materials in this study is done by using the simple payback period. This paper presents a systematic approach for optimization of insulation material type and thickness. The optimization is based on implementation costs and time required for construction works. This case study is done by using database obtained from several single family houses in Croatia which have undergone a process of energy certification and which currently do not have insulation layers on their external walls. Two insulation materials are considered in this study, rock wool and polystyrene insulation and various thickness of those insulation. Research results presented in this paper can be useful in the selection of thermal insulation material and insulation thickness when considering not only buildings energy efficiency improvements but also time spent for applying insulation layer on external walls and cost effectiveness of selected insulation.