Microcogeneration in buildings with low energy demand in load sharing application

The paper investigates the introduction of a MCHP (Micro Combined Heat and Power) system in buildings with low energy demand with respect to the current building stock. A load sharing approach between a multifamily residential building and an office one is taken into account. Dynamic simulations are carried out in order to evaluate the thermo-economic performance of the analyzed system. Particular attention is given to the estimation of the electric load of the different users, as the economic profitability of a MCHP system is strongly influenced by the amount of self-consumed electricity. In order to analyze the influence of climatic conditions, two different geographical locations in Italy (Naples and Turin, having 1034 and 2617 heating degree days, respectively) are considered. The results of this study indicate that the installation of MCHP systems in buildings with low energy demand allows to increase the percentage of self-consumed electricity reducing the bidirectional electricity flow between the users and the external grid, as well as the impact on the grid itself due to the large diffusion of distributed generation systems. Moreover this study shows that the load sharing approach between users with different load profile leads to better energy, environmental and economic results with respect to a conventional system. The climatic conditions play an important role on the MCHP operational hours and hence on the thermo-economic performance of the system. The primary energy saving of the system located in Turin is equal to 8.8% with respect to 6.2% of the system located in Naples. Also the environmental performance, evaluated in terms of equivalent CO2 avoided emissions, are better in Turin (8.3%) than in Naples (6.7%). The economic analysis shows acceptable values of the pay-back period in presence of economic support mechanisms. The findings of this study show that the introduction of a MCHP system in load sharing approach leads to thermo-economics advantages even considering the lower heating needs of well-insulated buildings.