It's often touted as the solution to housing affordability and the shortage of stock - building up, not out. But is there a downside to living in the air?
A new research project has recently been launched by the Universities of Exeter and Bath to find out just that. The aim of the study is to examine the effects of tall building motion and vibration on their residents.
Tall buildings such as skyscrapers are not rigid - they often sway slightly in the wind, with more movement felt at the top of building than on the levels close to the ground. There's some suggestion this movement and vibration can be linked to symptoms like nausea, tiredness and a lack of motivation.
It's known as "sopite syndrome" - identified in 1976, and characterised by sleepiness, apathy and difficulty in concentration.
Sopite syndrome is triggered by long-term exposure to gentle vibrations, including at levels lower than the current limit specified by the current International Standards Organisation Bases for design of structures.
"Humans spend 90 per cent of their lives in buildings which vibrate non-stop, but there is still very little reliable information about the effect of structural vibration", says Alex Pavic, professor of vibration engineering at the University of Exeter.
Professor Kenny Kwok, from the University of Western Sydney, has been using motion simulators to study the effect of building movement for more than 30 years, beginning at the top of Sydney Tower - then Centrepoint Tower - in the early '80s.
He says the new project will be about understanding the adverse effects of a building on its occupants, and will guide the formulation of acceptability criteria for building in the future.
He describes the effect of sopite syndrome. "You just don't feel well and you don't feel sick. But not quite right. Just on the margin."
While engineers and developers have enabled the construction of taller and lighter buildings that are more wind-sensitive, there is "insufficient research" on how building codes can prevent or limit the effect of subtle motion on a tower's inhabitants.
Kwok says there are "pros and cons" to doing tests in motion simulators. "It's fully controllable. You can shake it at any time you want, at whatever magnitude you want. But you can't control the weather."
Kwok, along with Steve Lamb from the Victoria University of Wellington, worked on a 2014 study that concluded "wind-induced building motion" mostly brought on mild motion sickness, which led to a reduced work performance.
Kwok says that studying the effects of building movement "in situ" is important. "The best test is to test a real building, and to test people. And this is why we decided to research in Wellington," he said.
Their study on CBD workers in the New Zealand capital showed that 41.9 per cent of the workers who felt building motion had trouble concentrating. But he noted building occupants in general almost never make formal complaints about building motion, suggesting the problem goes widely unreported. It also notes that women are more likely to report "adverse responses" to building motions than men.
More research, such as this latest planned study, is needed to document the interplay between the speed, frequency and duration of building vibrations, which can then be used to suggest a better way to design and build skyscrapers.