Lumped parameter models for energy auditing of existing buildings

The energy audit of existing buildings is usually a time consuming and expensive process, due to efforts required for data collection and modelling of audited objects. However, the modelling phase might be made less demanding, thanks to the development of reduced models, conceived in the form of lumped parameters models. They are shown very suitable because they require a reduced number of input data to be described. According to relevant literature, the detailed physical models take long time and they are often too expensive; they are adopted when a very detailed assessment is necessary. However, when preliminary energy audits of buildings can be made, reduced order models, usually defined as grey-box models, showed their reliability to achieve a suitable description of the thermal response of buildings in a short time. Thus, they are more cost-effective. The thermal parameters of the simplified model are usually extracted in real time; this allows to estimate the thermal response of a building in its current state, whose information can be reused to make predictions about its expected behaviour. The purpose of this work is to survey on an empirical procedure for deriving a lumped parameter model by means of measurements collected in a relatively short time period. In this way, owners and managers of real estates would be allowed to perform fast and cheap preliminary assessment on the opportunity to implement energy renovation actions. A first test performed in the machine laboratory of our department at the Universita Politecnica delle Marche for experimentally estimating thermal parameters will be described and results will be presented.