Heat insulation solar glass (HISG) is a multi-functional glazing technology, which has been developed at the University of Nottingham with an ultimate goal of mitigating energy consumed in buildings. HISG is capable of producing electricity when exposed to sunlight. It also differs from a conventional transparent photovoltaic (PV) module by providing some characteristic features such as thermal insulation, sound insulation, self-cleaning and energy saving as well as power generation. In this respect, HISG is very promising for both energy-efficient retrofitting of existing buildings and new-build applications. Therefore in this paper, an experimental attempt is made to investigate thermal performance characteristics of HISG. A test rig is constructed consisting of four different glazing configurations with the same thickness (air filled double glazed window, air filled double glazed window with low-e, argon filled double glazed window with low-e and HISG) and overall heat transfer coefficient (U-value) of each sample is determined in an environmental chamber through a standardized co-heating test Methodology. The results indicate that HISG is not only a power producer but also a good insulator. U-value of HISG is found to be 1.10 W/m(2) K. Maximum temperature difference between internal and external glazing is also achieved by HISG with 12.70 degrees C. (C) 2014 Elsevier B.V. All rights reserved.