“We need more Parises and fewer Manhattans” – Professor Francesco Pomponi
Edinburgh Napier-led research has found that low-rise, high-density environments like those found in Paris are the optimal urban form when looking to reduce greenhouse gas emissions over their whole life cycle.
The work, recently published in Urban Sustainability, builds on a growing debate around the design of future urban environments and was done in partnership with the University of Colorado.
The built environment is a big contributor to carbon emissions, global energy demand, resource consumption and waste generation. In the U.S., it accounts for 39 per cent of all greenhouse gases emissions, while in the European Union, it accounts for 50 per cent of all extracted materials and 42 per cent of the final energy consumption – making it a rich area for understanding and improvement related to climate change.
Co-author Jay Arehart said the study challenges current conventional understanding that tomorrow’s cities must be densely packed and stretch upwards to address and curb greenhouse gas emissions. The idea being that tall buildings make optimal use of space, reduce operational energy use for heating and cooling and enable more people to be accommodated per square metre of land.
“Both the urban sprawl that we see in the suburbs of the United States and the high-rise that we see in places like New York City are not necessarily optimal,” said Arehart. “We showed that new development should focus on minimizing whole-life carbon of buildings, not just the emissions from their operations or their materials. That density is needed for a growing urban population, but height isn't.”
The team investigated four different urban typologies – from dense-and-tall to sparse-and-low – by simulating 5,000 environments based on real-world data to establish their lifecycle greenhouse gas emissions.
This approach considered both premium for land (the extra land needed to build low-rise compared to high-rise) and premium for height (the extra materials to build high-rise compared to low-rise) to make comparisons fair said lead author Professor Francesco Pomponi, from Edinburgh Napier’s School of Engineering and the Built Environment.
"We developed a novel urban density metric to measure things up as accurately as possible," said Pomponi. "Our results show that density is indeed needed for a growing urban population, but height isn't. So it seems the world needs more Parises and fewer Manhattans – as much as I love New York – in the next decades."