## 7 Conclusions  
A highly efficient wind turbine with cross axis orientation for application in urban buildings has been designed and tested. The uniqueness of this design gives rise to its technical advantages over the conventional wind turbines and can minimize or completely eliminate the disadvantages of the conventional wind turbines. The idea of using horizontal blades as connecting struts for the CAWT is shown to have played a significant role in the improved rotational speed, power output and self-start behavior of the CAWT. The results obtained from the study showed that the coefficient of power (\(C_{p}\)) of the building integrated CAWT improved significantly compared to the building integrated straight-bladed VAWT. At \(Y=100\) mm, the \(C_{\text{p,max}}\) value of the CAWT increased by 266% at a TSR (\(\lambda\)) of 1.1 at a wind speed of 4.5 m/s compared to the straight-bladed VAWT under the same experimental conditions. Similar improvement in performance of CAWT is also observed for all conditions of height, i.e., \(Y=150\) mm, 200 mm, and 250 mm. The results obtained from the variation of height of CAWT above the rooftop showed that the closer the height of CAWT to the building rooftop, the better the performance of the CAWT. The result was verify from the CFD simulation which indicates that the 100 mm height has the highest skewed angle which helps to improves the performance of the building integrated CAWT. The building roof shape acts as an augmentation device by deflecting the free stream wind speed to the horizontal blades of the CAWT thereby enhancing it self-starting behavior and its overall performance. The 10\({}^{\circ}\) pitch angle for the horizontal blades is the optimum pitch angle for the CAWT. Increasing the pitch angle above this affects the performance of the CAWT by reducing the maximum \(C_{\text{p}}\) obtained. In addition, decreasing the pitch angle below 10\({}^{\circ}\) reduces the performance of the CAWT. Building integrated CAWT represents the future outlook of wind turbines in urban environments. However, there are some limitations from the study that require further investigations. The study was limited to a specific model wind turbine (CAWT) of high solidity, low power coefficient, and low Reynolds number flow regime. Therefore, it is necessary to study this new type of wind turbine in a wind tunnel with higher Reynolds number flow regime, more over the blockage ratio of the CAWT in the wind tunnel should be estimated. Although the results show a better performance closer to the rooftop, it should be known that closer to the rooftop, the air flow is turbulent and the machine experiences more turbulence and as a result more fatigue. It is therefore necessary to investigate the turbulence level closer to the rooftop where the CAWT was installed and its effect on the turbine cost and its lifetime. Studies on blade fatigue should also be one of the focus areas. Figure 16: Skewed angle for CAWT for \(Y=100\) mm, 150 mm, 200 mm, and 250 mm. Since the experiment were performed on a semi-open wind tunnel where the flow is not controlled, turbulent flow is expected, and the turbulence in the experimental area cannot be controlled due to the limitations of instruments and costs. The turbulence could affect the wind turbine performance; therefore, it is necessary to study the CAWT in a proper wind tunnel with higher Reynolds number flow regime and higher accuracy instruments  
The innovative design of the CAWT was intended to be very versatile and to excel in many different environments. It is an ideal solution for on-site building integrated wind turbines, especially in urban areas with relatively low to moderate wind speeds and a high level of turbulence. Future studies should include testing the CAWT for different roof shapes and performance prediction and/or CFD analysis of the flow field. The authors would like to thank the University of Malaya for the research grant allocated under the University of Malaya Research Grant (RP015C-13 AET).