Enduring Urban Forms
According to the United Nations, the world’s population is growing towards 10 billion, and by 2050 over two-thirds of us will live in cities.1 That means that for eveiy two cities today, there will be more than three of the same size by 2050. Cities will also need to get bigger and denser to handle this population growth. Will all these new cities and their buildings be planned to preserve access to daylight and views for their residents?
We can plan for the future by learning from how various cities have handled growth pressures in the past—some gracefully offering their residents ample access to light and air, some becoming increasingly more unlivable. There are many fundamental urban planning decisions that support access to more daylight and views, and there are many smaller scale fixes that can help a city improve incrementally over time.
In considering what strategies might be employed at an urban scale to improve access to daylight and views, it is useful to consider the time scale of each decision. Cities and buildings may seem very permanent. In reality, they are constantly in flux. Little improvements are made to update the wiring or the caipet. Bigger changes are made to move a wall or add a porch. At the urban scale, empty lots are filled in and new buildings replace old. Even historic preservation districts inevitably change the use of streets and buildings as cultures and technologies evolve.
Stewart Brand, in his masterful book, Ном Buildings Learn, explains how various building systems change over time.2 “Site is eternal” he quips. Largely determined by topography, and urban infrastructure, property lines last for hundreds or even thousands of years. Brand classifies building systems into the ‘six S’s,’ each with a different time dimension. In addition to Site, there is Structure, the foundation and load-bearing elements which are likely to last for at least 50 years, and perhaps up to 300 years, in stable societies. Next in time scale comes Skin, the fenestration and cladding of a building wall, designed to resist the onslaught of weather. On a well-built structure, the skin might last 50 or more years before it needs serious maintenance or upgrading. The other three elements—Services, Space Plan, and Stuff—have much more rapid turnover schedules. “They wear out or obsolesce every seven to 15 years,” explains Brand, and are regularly changed and upgraded to meet the needs of the new occupants and advances in technology. It is the first three categories—Site, Structure, and Skin—that are the primary determinants of access to daylight and views.