Hong Kong is high-densely built city with a big population. Tak Bo Garden is a residential project finished in 1984 including 2016 dwellings in several high rise buildings (33 or 40 floors). A study was operated about energy performance focused on daylighting and natural ventilation comprising an on-site study, numerical simulation and recommendations for improvements. Results show insufficient daylighting and difficulties to catch the wind in summer because of the density of the buildings. The report describes possible solutions for improving the situation.