In several situations, a heat pump for simultaneous heating and cooling (HPS) can be installed advantageously in buildings where simultaneous needs occur. Unlike a reversible heat pump that works alternatively in heating or cooling, a HPS operates under three modes: a heating mode, a cooling mode and a simultaneous mode. In this article, different types of buildings are simulated using Trnsys software to identify their needs for heating, cooling and domestic hot water production (DHW). The introduction of a ratio of simultaneous needs in heating and cooling (RSN) can qualify buildings in relation to the appropriateness of a HPS. Three kinds of buildings are investigated (a low-energy building, an office building, and a retail space) under three different climatic conditions in France. As the design of a heat pump is highly dependent on the refrigerant properties, models of small-to-medium HPS using R407C, R290 and HFO1234yf are developed. Results of experimental tests on a 15 kWheating-capacity HPS working with R407C were used to validate the numerical models of components and global model. Finally, a co-solving technique using two environments (EES and Trnsys) is used to compare the performance of the different refrigerants coupled to the building having the best RSN. (C) 2014 Elsevier B.V. All rights reserved.