Renovation of apartment blocks with BIPV: Energy and economic evaluation in temperate climate

Abstract This paper investigates the energy and economic profitability of renovating residential buildings in temperate climate through the integration of PV panels on facades. The investigation regards a real multi-storey apartment block, representative of a significant amount of edifices built in Italy in 1950–1990, which often need refurbishment because of obsolescence. This building type is generally well suited to receive a new double-skin facade, supporting both PV and other common cladding materials, while also representing a good compromise in terms of aesthetic quality, cost, weight, durability and ease of maintenance. In order to make general conclusions, a parametric analysis is performed, by virtually changing the orientation, the number of floors and the climatic conditions, and by considering different PV technologies. The results show that for an 8-storey building with the main axis along E-W, the initial investment can be repaid within around nine years, if considering the current fiscal incentives and a 50% self-consumption rate for the electricity produced by the PV modules. The presence of fiscal incentives is essential to make the investment attractive. Better PV efficiencies, lower prices and higher self-consumption rates can enhance the economic profitability, which may generate a significant impact on the retrofit of European multi-storey residential stock. These results can be effectively extended to the PV integration on the facades of new apartment blocks too.