Cities and climate change

Subject – Environment

Context – low-rise buildings are the future – not skyscrapers

Concept –

More than half of the world’s 7.8 billion people live in cities and urban areas. By 2050, an additional 2.5 billion will be living there.
More densely packed optimize the use of space and house more people per square metre and limit urban sprawl.
However, densely built, low-rise environments are more space and carbon efficient, while high-rise buildings have a drastically higher carbon impact.
Operational carbon is generated while a building is in service.
Embodied carbon is all the hidden, behind-the-scenes carbon produced during the extraction, production, transport and manufacture of raw materials used to construct a building, plus any produced during maintenance, refurbishment, demolition or replacement.
At a global scale, the construction sector is responsible for a significant impact on the environment, as is clear from the graph below.
- The largest contribution comes from its consumption of energy and resources, which boils down to the design stage — the part of the process that no one is looking at.

Passive House designs– a building standard that uses non-mechanical heating and cooling design techniques to lower energy use.
Near-zero energy builds– high performance buildings where the low amount of energy required comes mostly from renewable sources.
Skyscrapers rely heavily on concrete as a structural material. So the type of materials we use, how much we use, and how we use them is crucial.

High-density low-rise cities, such as Paris, are more environmentally friendly than high-density high-rise cities, such as New York.
- Looking at the fixed population scenarios, when moving from a high-density low-rise to a high-density high-rise urban environment, the average increase in whole life-cycle carbon emissions is 142%.