It is perhaps surprising to hear this from the executive director of the Council on Tall Buildings and Urban Habitat, but, in my view, perhaps 95 percent of current tall buildings are extremely disappointing, in both design and energy terms. Most are designed either as vertical extrusions of an ultra-efficient floor plan (the commercial rectilinear hermetically sealed "box"), or as ever-more-gratuitous sculptural forms whose only relationship to context is a visual one ("I am beautiful and I am here, so behold me"). This is homogenizing cities across the world to make a universal architectural mush of transferable icons; the skyline and icons may become synonymous with a place but are no more related to the local culture or environment than Starbucks or McDonalds are.
In energy terms, we also need to take a huge pinch of salt with any "net-zero energy"–skyscraper claims. We are a long way from achieving that holy grail, even if we just consider operational energy and not embodied energy. The reality is that, so long as we focus on single buildings in isolation, we will move forward in addressing climate change only very slowly. Of course we must do the best we can to reduce both operating and embodied energy in tall buildings, and harness natural energy where we can, but it is only in the bigger-picture scenario that tall buildings truly contribute to sustainability—through shared land use, resources, and infrastructure. The sooner the industry recognizes that and starts to put greater emphasis on consideration of infrastructure, the faster we will move forward with sustainable cities.
The key to resolving the negative issues raised here—degradation of both the local (homogenization of cities and culture) and the global (energy use, climate change)—is to tie the building into its location on every level: physical, philosophical, cultural, and environmental. That's what vernacular architecture has done for thousands of years—in many of the locations that are now being homogenized—so it's not clear why it's so difficult for contemporary architecture. There are so many opportunities for tall buildings to better engage with location and environment. Here are a couple, outlined below.
As we rise vertically from a site, conditions do not stay the same. The environment changes (the external air temperature at the top of the Burj Khalifa is considerably cooler than at the bottom), and the relationship between the building and the city changes. This should result in different approaches to building form, program, environmental response, skin, and expression at every "horizon" within the tower; skyscrapers should no longer just be the vertical extrapolation of an efficient floor plan.
It is ridiculous that cities are going ever more vertical but not providing more horizontal—that layer where the essential fiber of the city exists (circulation, recreation, community, etc.)—public zones that will bring a whole different dynamic to our buildings. We need to start physically connecting tall buildings with skybridges and urban habitat in the sky. This will also allow the open, communal, recreational (preferably green) spaces that are so crucially needed in tall buildings, as well as an embrace of functions for towers beyond the predominant office, residential, and hotel uses.
The good news is that all this is starting to happen, albeit too slowly, with Singapore at the forefront. There have been huge strides forward with tall buildings in the last decade or two, but there is still much to do. Creating net zero energy skyscrapers is only the beginning.