The City of the Future 2

Big and Tall Buildings

Facts:

No part of a large multistory building which is more than 15 feet from an outside wall is affected by outside temperature. Everything in a large occupied building that is further than 15 feet from an outside wall generates heat which must be removed with air conditioning or ventilation. Most very larrge buildings are not well ventilated. Two thirds of all energy use in the United States takes place in buildings. An equivalent amount of greenhouse gasses is generated from building use. Worldwide, other countries have an even higher percentage of energy usage in buildings, largely because they drive less and have more efficient transportation systems. Transportation accounts for less than a third of energy use and greenhouse gasses in the US and globally. Unfortunately, however, most of what we hear about the energy situation has to do with the price of gasoline at the pump.

There is obviously a gap in the understanding of the problem. But, as we get further and further into the downhill part of the energy supply bell curve, we will begin to see changes that affect building patterns as significantly as transportation habits. At the same time, it is important to realize that transportation and building patterns are flip sides of the same coin. To understand this we must examine what the urban pattern really is. In some ways, the urban pattern is like a piece of fabric. The fabric of a city consists of buildings and the spaces between the buildings. The exterior spaces are connective tissues. They contain roads, sidwewalks, train lines, and open space in the form of parks and specialized use areas such as outdoor cafes, streetscapes, playgrounds and so forth. They are places for the movement of goods, services, utilities and people. The buildings form walls for the outdoor spaces and define the look and feel of the larger city. Most American cities are made up of a dense central core of larger buildings surrounded by concentric rings of successively lower density districts transitioning to a low density suburban landscape. The stock of existing buildings is mostly made up of buildings put in place in the last 30 to 40 years. These are the buildings which will cause the most problems because they are almost totally reliant on cheap energy to remain usable. They were designed to be built as cheaply as possible for the desired use and they are largely unresponsive to the environment.

Newer large buildings, especially in Europe and Asia, are being built to allow for ventilation to cool the building core in winter and into the more temperate parts of summer. Vertical wind tunnels in the core of some new large buildings draw cool air in from windows and vents on the outside and channel it up using convection to create air flow. Some new buildings even incorporate windmill generators into the air flow to generate electricity. Creating this type of air flow in an existing tall building would require a major structural rebuild of the central core of the building and an accompanying loss of usable space. Retrofitting existing large buildings to make them more environmentally responsive is difficult and very expensive. In many cases the work would cost more than the worth of the building. The difficulty and expense of energy renovations portends a loss of existing buildings unless they are seen as being valuable enough to make extensive rebuilding worthwhile. The resulting abandonment of existing building stock may well result in abandonment and disinvestment in large areas of existing cities. Always on the look out for new opportunities to build, the development community will push to replace existing stock with new buildings, but in new areas which have a brighter future and in areas where it is cheaper to build from scratch rather than having the additional cost of demolishing existing stock.

Following this pattern, cities may continue to become a patchwork of viable new and abandoned older areas. while the much older areas with environmentally responsive building stock (i.e. buildings having windows that open) will renovate and areas of underutilized and abandoned low density uses (such as industrial zones) will be redeveloped with new, more energy efficient building stock. Already most American cities are seeing a land rush to buy and redevelop older inner ring industrial and warehouse districts which have lain unused for much of the last 50 years. The new uses being proposed in these areas are largely mixed use with densities and forms reminiscent of the period of time from the beginning of the industrial revolution to the dawn of the international movement in architecture which began to flower in the late 1920’s.