Plastic transparent components are increasing their share in the glazing market since they provide good performance with a weight significantly lower than glass and at competitive costs. Typical products are coextruded polycarbonate multi-sheets systems, UV-protected to avoid the quick ageing. These components have limitations on the size and need to be bonded each other via male-female joints that could be a weak point for the facade. This study is focused on the thermal and optical characterization of three polycarbonate systems for buildings (with different number of chambers and geometry). Thermal transmittance measurements were carried out using a hot-box apparatus, in order to assess the impact of the connection joints on the effective U-value and to compare it with data declared by manufacturers, usually referred to the centre of the component. The optical characterization was carried out to monitor the same issue for the light and solar properties, by means of a large integrating sphere apparatus. The investigated polycarbonate systems could be a valid solution in place of classic windows in commercial buildings and the study provides a deepened knowledge about the polycarbonate panels' thermal and optical behaviour and a set of useful data for accurate analyses in building integration. (C) 2013 Elsevier B.V. All rights reserved.