This study combined curtain wall structures, building construction practices, heat transfer mechanisms, and natural circulation loop designs to develop an innovative, wall-integrated solar heater based on the concept of an energy-harvesting facade. The heat transfer performance of this prototype was investigated experimentally. The results indicate that the average Nusselt numbers and flow thermal resistances in the heated and cooled sections increase and decrease, respectively, with an increasing modified Rayleigh number under isothermal boundary conditions for the heat sink. During daily use conditions, the system-wide energy harvest ratio of the test cell is between 0.45 and 0.78 and is not significantly affected by the cooling (feed) water flow rates. (C) 2014 Elsevier B.V. All rights reserved.