When there is the desire to achieve optimal temperature control for a building or its energetic performance description, one of the steps that should be followed is to identify experimentally the dynamic model for heat transfer in that building. In these models there are used heat equations in time domain, but as these systems have multiple inputs and outputs, these equations can be represented in matrix form. In this manner, we can easily obtain the state-space representation and subsequently the transfer function representation. Furthermore, the model parameters can be determined easily. It will be used as an example for a detailed study, a normal size house for which a number of inside and outside parameters are monitored.