The present study is focused on the analysis of the performance of a Peltier cell integrated in an adiabatic box in order to work as a heating and cooling unit. The box is a reproduction in small scale of the room of a building where a specific comfort temperature must be accomplished. This experimental setup is part of a continuous work which has developed several real scale prototypes. Thermoelectric modules are becoming a usual solution in different fields. Its use in architecture and building services is still an innovative application, far from the market but increasingly researched in the last decade. The ability of heating and cooling in a unique device, the low maintenance requirements, noiseless properties and the possibility to be supplied directly by photovoltaic panels are some of the most remarkable advantages to implement this technology in architecture. The application of thermoelectricity in buildings is not focused on the thermoelectric performance itself, but in the achievement of a comfort indoor temperature. Thus, one of the main key issues in this adiabatic box is the achievement of the perfect temperature control and the relation between the heat released or absorbed by the Peltier, and the room temperature. The main goal of this article is to analyze and quantify this relationship to be able to optimize the performance of the Peltier cell in relation to the conditioned space and apply this knowledge in future architectonical prototypes, since no equivalent developments have been found in the integration in buildings and not only from the development of thermoelectric equipment.