Throughout present research, optimization investigations of an irreversible absorption heat pump system on the basis of a new thermo-ecological criterion. The objective functions which considered are the specific heating load, coefficient of performance (COP) and the ecological coefficient of performance (ECOP). Three objective functions of the ECOP, COP and the specific heating load are optimized simultaneously using the multi-objective optimization algorithm NSGAII. COP and ECOP are maximized and specific heating load is minimized in order to get the best performance. Decision making is done by means of three methods of LINAMP and TOPSIS and FUZZY. Finally, sensitivity analysis and error analysis was performed for the system. (C) 2014 Elsevier Ltd. All rights reserved.