Denser and Taller Urban Environments: Is it the Right Path to Sustainability?

  • Author(s)
    Ruth Saint, Niaz Gharavi, Jay Arehart, Francesco Pomponi, Bernardino D’Amico

Population and urbanisation are increasing with an estimated additional 2.5 billion people living in urban areas by 2050. The built environment is the greatest cause of carbon emissions, global energy demand, resource consumption and waste generation. Therefore, achieving optimal use of space and maximal efficiency in resource use is fundamental if a sustainable tomorrow is to exist. In the built environment there has been a growing belief that taller and denser is better, under the idea that tall buildings make optimal use of space and enable more people per square metre of land to be accommodated. The aim of this research is to investigate which building forms yield maximal efficiency in terms of accommodated population, land use, energy demand, whole-life carbon emissions, and resource consumption. Through case studies and parametric modelling, four realistic urban scenarios have been developed and analysed for WLC: 1) low density, low-rise, 2) low density, high-rise, 3) high density, low-rise, and 4) high density high-rise. These scenarios were then modelled under two conditions; a fixed land area of 1 square kilometre and fixed populations of 20, 30, 40 and 50 thousand people. Key findings from this analysis include that density has no significant impact on WLC while building height significantly impacts WLC. Furthermore, the results show that there is no merit to the claim that building denser and taller urban environments is more sustainable. This multi-criterion approach extends the partial view of most existing research and will enable better-informed decisions for designers, urban planners, and policymakers by providing a more holistic picture of what sustainable urban environments should look like.

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The linear regression results are super interesting. Places with higher density and lower density have every different relationship in the whole life carbon versus land area. Very interesting.

Very nice work! I'd like to understand better the definition of whole life carbon. Could you explain briefly? Is energy use in the buildings considered?

Thanks KK!

Hi Peter. Yes, whole life carbon (WLC) includes building energy use. It's a definition that has been most widely used from the RICS professional statement as to what life cycle stages should be considered (system boundary) and what components of a building should be included. This is a project that we're continuing to expand and investigate further, with the preliminary finding being that building tall increases WLC regardless of the number of inhabitants of the land area available.

I wonder what kind of societal impacts your findings could have if your research sentiments were implemented by policy makers or other actors?

I see, thanks for explaining. So the building energy use is modelled using a building energy simulator, or based on MJ/m2 approach?

I am curious that density isn't found to decrease WLC then. Is reduced floor space per capita included the the calculation of building energy consumption under increased density?