This paper presents a multi-functional (sensing -actuating) greenhouse ventilation window design heated/cooled naturally by convection, to overcome different industry challenges in terms of designing smart applications. This ventilation window design includes a smart C-shaped NiTi actuator and three-pulley system, and all attached to the window. The force generated in the NiTi wire shrinks the C-shaped to open the ventilation window when the environmental temperature increases. When the environmental temperature decreases, the C-Shaped NiTi actuator returns to its initial position and closes the window. This smart actuation allows energy saving due to natural phase transformation induction (i.e. convection) and high force generation compared to the small NiTi wire mass. Using the pulley system is important as well to reduce the load on the NiTi actuator and enhance its long-life time. In this paper, the smart ventilation window actuator design has been disused followed by a simulation study to investigate the NiTi C-shaped element behavior. The simulation results predict the thermomechanical behavior of the NiTi wire at the proposed greenhouse environmental conditions and the force generated in the wire. For future studies, an experimental investigation could be done to prove the simulation results.