Solar water heater (SWH) is increasingly used in the urban area where the collectors are liable to be shaded by nearby buildings, however, the effect of nearby buildings on the behavior of SWH has not yet been understood well. This paper presents an integrated approach to quantitatively evaluate the performance of SWH in the obstructed scenes of arbitrary geometric complexity by coupling the radiation model in the urban resource flow tool CitySim with the SWH model developed in TRNSYS. A case study is conducted to illustrate the effect of the obstructions on daily and annual thermal performance and annual primary energy consumption of SWH. The results from the case study reveal that the SWH with typical configurations in the obstructed context may consume more primary energy than conventional water heater does, however this is not the case for the SWH in the unobstructed context. Fortunately, using the proposed approach can effectively avoid this problem. Thus, the proposed approach is useful for making better use of SWH in the urban context to maximize energy saving. (C) 2013 Elsevier B.V. All rights reserved.