Skyscrapers are already very efficient. They fit more usable floorspace into their ‘footprint’ than any other type of building does. They conserve energy that gets used for heating and cooling by exposing less of that floorspace to the outside weather. For all that usable floorspace, they need only a single roof.
Think about it. A relatively short ten story building contains as much floorspace as ten single story buildings that occupy the same area individually, but collectively occupy ten times as much area! Nine of those stories loose heat during cold weather, and collect heat during hot weather, only around the exterior walls. Only the top floor loses and collects heat through the roof, and only if there is not an upper utility ‘attic’ floor that insulates it. Ten single story buildings of the same area are all exposed on top, as well as all the way around. Of course, ten single story buildings of the same area need ten roofs comparable to the single roof of the ten story skyscraper.
Skyscrapers certainly need more infrastructure to support all of their floors, and they lose a bit of their floorspace to that infrastructure, as well as to the elevators needed for access to the upper floors. It also takes significant energy to pump water up to upper floors. Regardless, skyscrapers are still the most efficient of buildings. They have nothing to prove to the treehuggers who dislike them so.
‘Green roofs’ on top of skyscrapers are a fun concept. They utilize space that is otherwise useless, and they really do help to insulate the top and most exposed floor of big buildings. However, they are no more ‘green’ than landscapes that are at ground level. In fact, they necessitate the incorporation of extra infrastructure into their respective buildings in order to sustain their synthetic environments, and to support the extra weight of the soil, water and flora. Pumping water to irrigate green roofs takes more energy than irrigating landscapes at ground level. Generally though, they are probably worth the effort, as long as they are not too elaborate,
Chia Pet Skyscrapers are what happens when they get too elaborate. The vertical landscapes incorporated into the facades of these buildings consume more resources and energy than they conserve. Although less energy is needed for cooling the buildings during warm weather, more energy is used to pump water for irrigation. Not only must the buildings be constructed to sustain these landscapes, but they require much more specialized maintenance than conventional skyscrapers need. Because the flora in these vertical landscapes can not disperse roots into real soil, the growing medium must be fertilized very regularly with more synthetic fertilizer than conventional landscapes in the ground need, and all this fertilizer eventually leaches into the drainage systems of the landscape. Insects might enjoy these vertical landscapes, but the necessary regular maintenance would prevent much other fauna from getting established like they could in conventional landscapes at ground level.
Although the skyscraper within this spectacular Chia Pet Skyscraper benefits the environment, the vertical landscape that adorns the exterior only benefits those who live and work in and around it.