Apartment Building In Berlin

• Energy use
Buildings between 4 and 7 stories have a lower energy footprint per m2 than do high-rises greater than 7 stories. There seems to be a tradeoff with many other variables in a life cycle analysis, which would suggest that 7 stories (around fifty dwelling units per hectare for optimum transport petroleum use (Kenworthy)) is the optimum density in T1 urban areas, the city of Paris being an example (Mehaffy). Buildings not requiring lifts (around 4 floors, though it could be five with a final two storey apartment (maisonette)) are normally more energy efficient. Note, this is dependant on the particular country's accessibility requirements.
• Climate factors
High-rise buildings cast a significant shadow over nearby buildings, reducing solar energy harvesting. They also cast shadows over public spaces, reducing their amenity value, and these spaces are a very valuable resource in mid-density cities. Wind turbulence can also be a significant problem at ground level if design provisions are not made. The prevailing cooling breezes in summer can be disrupted for nearby buildings also.