This paper simulates the annual overall energy performance of an amorphous silicon (a-Si) based photovoltaic double-skin facade (PV-DSF) in Hong Kong. Based on EnergyPlus, a numerical simulation model was developed to simulate the thermal, power and daylighting performances of the ventilated PV-DSF simultaneously. The overall energy performance of the optimized PV-DSF was calculated. Per unit area of such PV-DSF was able to generate about 38 kWh electricity yearly in Hong Kong. The studied PV-DSF is also featured with pretty good thermal and daylighting performances. A great amount of solar heat gain was blocked by the PV module, which resulted in a lower solar heat gain coefficient (SHGC) for the PV-DSF. At noon of sunny day, the maximum daylighting illuminance reached 470 lux, which was very close to the design illuminance level. Thus, if combined with a dimmable lighting control system, the semi-transparent PV-DSF could reduce considerable lighting energy use. Moreover, with the efficiency improving of semi-transparent PV modules, the overall energy performance of PV-DSFs would be further improved, and thus it would be more and more promising.