An application of a novel steady-state simulation of a monovalent inverter-driven water-to-water heat pump with a desuperheater is presented. The simulation is capable of modeling and managing the different operation modes of the system such as combined space heating and domestic hot water, in order to provide realistic results, from which four control schemes based on two electricity tariff plans were developed. The schemes were tested on a subject low energy house for Tokyo and Sapporo, in Japan, for the coldest day of the year and for the heating season. Emphasis was given to the short-term domestic hot water storage. The results show that the application of the schemes with a flexible electricity tariff had lower cost over the scheme that used the flat rate pricing plan. Moreover, it was shown that no unique scheme was able to minimize the cost and electrical consumption for both locations. Additionally, a tradeoff between lowest cost and lowest energy consumption was identified for Sapporo. The results of this research could be applied to develop a more robust control on monovalent heat pump systems. (c) 2013 Elsevier Ltd. All rights reserved.