Julia Park on coronavirus, zero carbon and the implications for density
Coronavirus probably isn’t helping but I’ve found myself preoccupied by two particularly poignant warnings about climate change – both in the new LETI (London Energy Transformation Initiative) climate emergency design guide.
Firstly, writing in the foreword, Pooran Desai (chief executive of oneplanet.com and co-founder of Bioregional) asserts that unless we change course drastically, leading scientists believe that the world will only be able to support 0.5 to 1 billion people, within the lifetime of people alive today. Secondly, (from the UN Global Status Report 2017), that over the next 40 years the world is expected to build 230,000 billion sq m of new construction – adding the equivalent of Paris to the planet every single week.
I should have known about both, but I didn’t. I did know that world population is approaching eight billion but I had no idea that the rise from one billion to the current figure of 7.8 billion has happened in just over 200 years (world population hit one billion in 1800) or that as recently as 1960, (only 60 years ago) it was still only three billion.
According to the latest figures from World Population Growth, the average population density across the world (measured as the total number of people divided by the total area of land) is 25 people per square kilometre. Needless to say, the distribution varies hugely by country. Singapore has nearly 8,000 people per km2, more than 200 times as dense as the US, and 2,000 times the density of Australia. Of the larger countries, Bangladesh is the most densely populated with 1,252 people per km2. Lebanon is next with 595, followed by South Korea (528), the Netherlands (508, and the one that surprised me most) and then Rwanda (495). Greenland is the least dense (less than 2), then Mongolia, Namibia, Australia and Iceland. This source didn’t include England or the UK, but a different data set gives England a density of 424, and the UK as whole, 274.
That got me thinking about cities. Different data sets give different results. Some say Tokyo is the densest city on earth, but only if it’s based on “Greater Tokyo”. Citing the UN Habitat data, an interesting article in the Guardian in 2017, ranked Dhaka the world’s most densely populated city with a density of 44,500 people per km2. Mumbai was second, Medellin (in Colombia) third, Manila and Singapore, Casablanca and Lagos all close behind.
The same article looked at the causes of high density. Among the many geographic and economic factors, they mention an “island effect”. Male, the capital of the Maldives, is an island city with an area of just 5km2 and a population of more than 130,000. The buildings aren’t particularly tall but making the most of every piece of land has resulted in a density of 23,000 people per km2. That’s modest compared with the coal mine of Hashima Island near Nagasaki though. Before it was abandoned in 1974, more than 5,000 people were living on an area 400 metres long, at a density of more than 83,500 people per km2.
The densest urban environment created so far is thought to be Kowloon Walled City, a dense cluster of 12-storey apartments in Hong Kong, demolished in the 1990s. A census in 1987 recorded a population of over 30,000; a density of well over a million people per km2.
The widespread explosion in the densities of modern cities that is linked to global population growth is largely due to two inventions: concrete and the lift. Together they made super-tall buildings possible, but we haven’t given much thought to the consequences. Undoubtedly sustainable in terms of efficient land use, what impact are they having on our lives and our planet? I wonder whether Kowloon Walled City’s reputation as a lawless place was related to its density. And what do we do when these buildings start to fail simultaneously – not an unreasonable proposition in places that have undergone rapid growth.
If the answer to any of these questions is ‘no’, what’s the alternative?
Ranked as the city with the 33rd highest population density, London is a case in point. Tower Hamlets, one of its largest and densest boroughs, has already seen huge growth, but its population is expected to increase to 400,000 by 2031 which means it needs roughly another 60,000 homes. Most of its newest homes are in high-rise buildings and, to the great credit of the planning department, a small team embarked on a research project which involved talking to more than 1,000 residents of nine tall buildings about what works and what doesn’t, and what might work better.
The findings, which are available online, have led to a new SPD with a raft of guidance and standards informed by the feedback. The aim is to influence the design of the next influx of new homes. It’s all really good except for one thing. For a number of reasons, many of them political, no one is really able to question whether that level of growth is sustainable either socially or environmentally, given that only more high-rise buildings can possibly deliver the numbers.
To achieve “whole-life net-zero carbon”, the definition adopted by LETI, new buildings must not only achieve net-zero operational carbon without the use of fossil fuels, they must also be wholly constructed from re-used materials and designed and built to allow 100% of the materials to be disassembled and re-used.
Is that even possible with high-rise buildings that rely on the use of concrete and lifts? And, if it’s not (and I genuinely don’t know) is it right to build more? Has the London mayor been right to expect boroughs to meet targets that can only be met by building typologies that can’t meet the meaningful definition of zero carbon? Does the secretary of state have the right to pick a fight with Khan about his failure to build enough homes? If the answer to any of these questions is “no”, what’s the alternative?
Perhaps coronavirus is making me unduly pessimistic, but we may have caused that too. Ecologists suggest that it was our actions – taking wild animals out of their natural habitats allowing pathogens to easily trans-migrate – that caused the mutation that led to the virus. No one likes a die-hard pessimist, but optimists often unfairly characterise realists as pessimists. Wherever you fit on that spectrum, we all have a lot to think about as we self-isolate and contemplate the global effects of our individual and collective actions.
Julia Park is head of housing research at Levitt Bernstein