## 4 Conclusions  
A series of experimental tests has been carried out in a boundary layer wind tunnel to measure both the velocity field and the surface pressure above the roof of a high-rise building. Besides providing validation test cases of future numerical investigations, the study aims at improving the understanding of the flow pattern of the roof region for wind energy harvesting. The effects of wind direction and roof shape have been investigated in terms of flow pattern, turbulence intensity and accelerated wind velocity. For all wind angles, the flow separates at the leading edge of the flat roof. Nevertheless, different separation patterns take place, depending on the angle of the wind, which are visible in both the surface pressure and wind speed profiles. At 0\({}^{\circ}\), the separation bubble extends to about 2/3 of the building width, with a height of about 0.3\(D\). In contrast to the separation bubble, cone vortices dominate the flow pattern at 30\({}^{\circ}\) and 45\({}^{\circ}\). The cone vortices grow in size as they evolve along the side of the building. The largest size for cone vortices is found at 30\({}^{\circ}\). As a broad region is affected by the separation, the 0\({}^{\circ}\) configuration is the most turbulent one. In general, as the wind angle increases, the region of high turbulence intensity reduces gradually, and 45\({}^{\circ}\) is found to be the most preferable wind direction, minimising turbulence. As regards the flow acceleration, the 0\({}^{\circ}\) configuration provides the highest increase in wind speed, up to \(U\)\(\sim\)1.3\(U_{ref}\) at \(z\)\(\sim\)0.3\(H\) at the centre of the roof. However, this position is still influenced by relatively high turbulence intensities. On the other hand, the 45\({}^{\circ}\) wind direction provides a substantial amplification of wind speed up to 20%, at significantly lower positions close to the roof with a lower turbulence intensity. This vicinity to the roof is the determining factor for the installation of small wind turbines. A similar behaviour is observed in comparison with the flow over low-rise buildings. Namely, similar flow patterns are recognised for different flow angles and besides, similar areas are detected as the most favourable locations for the possible installation of wind turbines. In addition, an increase in building height seems to be followed by an increase in wind acceleration. Yet, more detailed studies are needed to provide more definitive conclusions on the relation between building features and wind resource. Decking the roof significantly improves the flow for wind energy purposes. Among the most important observations is the insensitivity of the flow above the deck roof to changes in wind direction, unlike in the flat roof case. Results also show a far smaller separation zone for all wind directions, which is beneficial as wind turbines can be installed closer to the surface. Turbulence intensities are equal to or lower than the reference value of the free-stream wind profile for all configurations, highlighting the advantage of this shape. Besides the favourable effect on turbulence intensities at lower heights, the deck-roof shape performs well in terms of enhanced wind acceleration, reaching a maximum increase in wind speed of around 20%. **Author Contributions:** Conceptualisation, H.H., A.S.G. and G.V. ; methodology, validation, resources H.H. and A.S.G. ; formal analysis, H.H., A.S.G. and K.K.V. ; investigation, H.H., A.S.G. and R.H.; data curation, A.S.G. and K.K.V. ; writing--original draft preparation, H.H. and A.S.G. ; writing--review and editing, A.S.G., K.K.V. and G.V. ; supervision, R.H. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by the COST Action TU1804 WINERCOST--\"Wind Energy to enhance the concept of Smart cities\" through a Short Term Scientific Mission to conduct the experiments. Further, this work was supported by the Luxembourg National Research Fund (FNR) under project reference C19/SR/13639741.