This paper is concerned with the development of a mathematical model capable of describing the quasi-steady state performance of an integrated ground source heat pump which is used for heating and cooling of an institutional building located in a Mediterranean climate The model is structured on functional basis according to the heat pump vapour compression or primary circuit a secondary ground loop circuit and a secondary building loop circuit Heat pump heating and cooling capacities as well as COP are considered to be dependent variables and are estimated in the model using performance fitted maps Independent variables include compressor speed circulation pump speeds ground loop return temperature and building circuit return temperature The model is validated using data from a full-scale ground source heat pump installation The validated model is used to examine system capacity and performance sensitivity to different control optimisation strategies including set-point control of room air temperature room air bandwidth temperature building loop return water temperature and building loop return bandwidth temperature (C) 2010 Elsevier B V All rights reserved