Physisorption heat storage in buildings can be a key technology for a more effective use of heating energy. However, a better understanding of key factors influencing the design and control of such systems is necessary. This paper presents the sensitivity analysis of the modeling parameters in the case of an open zeolite 13X/moist air heat storage system for building applications. The quantities of interest are the heat storage density and the discharge power density of the system. At the beginning, the whole analysis space is composed of 21 physical properties and 7 operating conditions and geometrical properties. After a first threshold selection, analysis of variance is carried on the remaining parameters, with a full factorial design of experiments to perform a complete sensitivity analysis of the model. The results show that only 3 thermophysical properties, i.e. the heat of adsorption, the water vapor molar mass and the adsorption equilibrium, and 3 operating conditions and system geometry parameters, i.e. the inlet relative humidity, the bed length and the inlet fluid flow rate, drive the outlet power density and heat storage density. The way those 6 parameters influence the outputs is also discussed and quantitatively assessed. (C) 2019 Elsevier Ltd. All rights reserved.