Why are there so many tall and super tall buildings under construction?

Tall, super-tall (300 meters or 984 feet or more) and even super-tall (at least 600 meters or 1,968 feet) buildings are being added to the skylines of cities around the world.

University of Illinois Urbana-Champaign professor of architecture Abbas Aminmansour specializes in steel and rebar design Concrete texture and of tall buildings. He is one of four Fellows selected globally by the Council on Tall Buildings and Urban Habitat in 2022, and a member and former chair of the Chicago Commission on Tall Buildings. He spoke to the arts and humanities editor of the News Bureau Jodi Heckel about the challenges of build super high.

Why do developers build tall and super tall buildings?

The main reason is the need for space, both residential and commercial, in urban areas. Globally, every month about 10 million people move to urban areas. Some very large cities don’t have much land to build on, leaving developers to build tall, super-tall or even super-large buildings. There have even been cases where project owners purchase so-called overdevelopment rights from adjacent buildings to build a taller building on their property. And there are personality aspects of some developers and occupants who want to build taller than the competition or have an apartment or office address in a super-tall building.

Cities whose skyline consists of tall buildings are seen by many as forward-looking and prosperous cities. In addition, tall buildings have proven to be magnets for new development, bringing in more businesses and helping the local economy. Once completed, a number of high-rise buildings are in the portfolios of insurance and investment companies, bringing economic benefits to many people, not just developers.

What are some of the technical challenges with tall construction?

High-rise buildings are susceptible to lateral movement, or drift, caused by wind or earthquakes. As a result, you need a reasonable amount of structure in excess of what is needed to support the weight of the building and its contents to ensure that building movement is within acceptable limits. An over-moved building is not necessarily structurally unsafe but can make people feel nauseous and can damage walls, pipes, or the elevator system.

Then there is the design of the elevator system. You want enough elevators to provide reasonable waiting times for users. At the same time, the elevator shaft occupies the area on each floor. That is a potential loss of revenue for the owner. Recently there have been improvements that allow the elevator car to move not only vertically but also horizontally over certain floors to allow more than one elevator car to operate in the same shaft, thus increasing efficiency. fruit.

Mechanically, you need to supply water and conditioned air to very high altitudes for occupant consumption, as well as for fire suppression systems. Just imagine water pressure in pipes at the foot of a tall building. It is very large and requires many materials and equipment for its operation. From a construction point of view, you need to take the material to great heights, which requires special equipment and expertise.

These are all very obvious challenges with solutions. It is important for architects, structural engineers, Mechanical Engineer and even contractors work in an integrated way to design a building that meets the architectural aspirations of the project and is economical to build and operate.

Are tall buildings as energy efficient and sustainable as shorter ones?

High-rise buildings are often designed by the best in their craft and are as efficient and economical as possible. However, they are not as sustainable as their shorter counterparts. For example, modern high-rise buildings have a significant amount of glass on their exterior walls. Glass is not the most energy efficient material when it comes to heat gain and heat loss.

And there are the challenges we talked about earlier. For example, to have a structure that is rigid enough to limit the drift of a tall building, more structural materials are needed than for lower buildings with a similar total floor area. So if you use the same gauge that we use for other buildings—energy consumptionthe amount of building materials used, the effort and energy consumed during construction, and the carbon footprint per square foot of usable floor space—tall buildings are not as sustainable as tall buildings. lower house.

However, they have what I would call a significant sustained impact. Imagine a tall residential building with 400 apartments in downtown Chicago. If these settlements were to be built in the suburbs, they would take up a significant amount of land – possibly agricultural land – and require critical infrastructure such as new roads, water, sewage, electricity, gas and other services, requiring a large amount of investment costs. materials and has a high carbon footprint. In addition, there is a need for repair and maintenance of roads and other infrastructure, variety of vehicles on the road, fuel consumption and smoke generation, travel time and other factors.

So no, tall buildings are not as sustainable as low ones, but they do have a significant sustainability impact. We just need to think further, both figuratively and literally, when considering sustainability.