High-density living worse for environment than suburban sprawl, new study shows

Living in a high-rise tower in the city is much less environmentally sustainable than moving to a house in the suburbs and adding to the urban sprawl, a shock new study has found.

In a revelation that challenges the long-held assumption that it’s more efficient to reside in a vertical village than a horizontal one, the three-year US study shows that apartment dwellers consume more energy, spend more of their time travelling and use their cars more.

“The findings are a little surprising to us all,” says Dr Anthony Wood, executive director of the Chicago-based Council on Tall Buildings and Urban Habitat (CTBUH), a research professor in the college of architecture at the Illinois Institute of Technology, Chicago, and co-author of the landmark report.

“We’ve all grown up thinking that urban density and verticality is a good thing but there has never been a study that has really looked at this in any detail; they’ve all been generic studies, based on large sets of generalised data. So we thought we should undertake a more focused study to prove it. And the results have been quite the opposite to those we thought we would find.”

The study, Downtown High-Rise vs Suburban Low-Rise Living, minutely examined the lifestyles, movements and energy bills and usage of 249 households living in high-rise towers in the city of Chicago. At the same time, it collected the equivalent data for 273 households residing in houses in the suburb of Oak Park, 11 kilometres from the CBD, and compared the two.

The outcomes, released on Tuesday at the annual international CTBUH conference this year being held in Australia, were staggering.

Downtown high-rise residents were found to consume 27 per cent more electricity and gas per person than the suburban residents, and on a square metre of space average, they consumed 4.6 per cent more.

Despite the fact that some of the energy use in high-rise was from the lifts in buildings and common lighting, pools and gyms, suburban homes have a far greater surface-to-volume area, with high ceilings, unattached walls and large roofs, and most of the houses in the study were large, wooden-framed and, on average, 98 years old.

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In terms of embodied energy – the quantities and specifications of materials used in the construction of both types of housing – high-rise fared even worse. The project found that high-rise buildings required 49 per cent more embodied energy to construct per square metre, and a stunning 72 per cent more on a per person basis.

“That was astonishing,” says Dr Wood, who undertook the research with Dr Peng Du, China office director and academic coordinator at CTBUH, and a visiting assistant professor at Illinois. “To see that on a square metre basis that the high-rise took up almost half as much energy again to build as low-rise took us, again, by surprise, and we would expect these kind of results to be the same in other cities around the world.”

Traditionally, it’s believed that one of the reasons people move into city apartment buildings is so they don’t have to spend so much time travelling, particularly on a daily commute to work. But here, again, the study delivered another bombshell, showing that downtown residents spent 11 per cent more time travelling a year.

Although they did spend less time travelling to work – 37 per cent of the total travel distance against 62 per cent of the suburban residents – it’s thought the travel times may be longer because city residents walk and bicycle more, and because they are spending a greater proportion of their travel time going to shops, restaurants and entertainment.

In addition, they spend more time visiting friends and family, possibly because those people still live in suburban houses and haven’t made the move to the city with them. “But the whole thinking of the industry is that if you’re living in town, you spend less time travelling,” says Dr Wood. “And that’s not really the case at all.”

High-rise residents were also found to own more cars (0.6 cars per person as against 0.5 in the suburb) and travel longer distances in them, 9 per cent further per year.

On the plus side for city centre high-risers, they were discovered to use less water – 73 per cent of the water used in suburban households, they took fewer separate journeys a year (92 per cent of those taken in the suburbs), and they walked and cycled nearly three times more.

One factor that may have skewed the findings is that high-rise city residents were generally older than those in the suburbs with an average age of 51 compared to 31.8, and were wealthier. 

“With more than a million people moving into cities around the world each year, it’s always been assumed that it’s much more sustainable for them to move into high-rise towers than into suburbia,” says Dr Wood, who is now hoping to conduct a much bigger study, involving more households in different areas.

“But this has shown that it’s not enough to say, yes, we have increasing density, so more sustainability, job done. We need to put more work into understanding how high-rise residents are living, and how their buildings work.”