How a simple idea could help cool urban habitats of the future

Based on United Nations estimates, the global population is growing by 1.18 per cent annually or an additional increase of 83 million people every year. In short, the world’s population is projected to increase by more than one billion people within the next 15 years, reaching 8.5 billion in 2030, and to increase further to 9.7 billion in 2050 and 11.2 billion by 2100.

According to UN Habitat, the number of slum dwellers is estimated at 863 million by 2014 account, compared to 760 million in 2000 and 650 million in 1990. They account for around 33 per cent of urban populations. Combine these two, add increasing global temperatures to the mix, and humanity stands on the brink of global crises: An ever-increasing urban population, the need to meet global housing demands and unprecedented consumption of energy to accommodate the numbers.

The release of Nasa’s mid-year climate analysis concluded that last year could have been the hottest on record (at least based on the first six months). The World Meteorological Organisation confirmed this at the Marrakech Climate Change Conference last November.

If one were to examine the data over the past 50 years, the average global temperature has increased at the fastest rate in recorded history. And, since 2000, experts have observed that the trend is accelerating: All but one of the past 16 years were the hottest years in Nasa’s 134-year record.

The ticking “time bomb” created by global warming and global housing demand (due to population growth) creates an urgency to search for a solution to house people in decent and energy-efficient living quarters in major urban centres, especially in developing Asian countries.

Recognising temperature increases, the global community has recently concluded a landmark deal in Kigali, Rwanda, on limiting hydrofluorocarbons used in, among other things, air-conditioners and refrigerators. This has positive and negative impacts. A New York Times article emphasises how the use of air-conditioning is both a boon and a bane when it comes to saving lives vis-a-vis climate change.

A recent study states that the number of deaths as a result of very hot days in the United States declined by up to 80 per cent from 1960 to 2004, thanks to the adoption of air-conditioning. In contrast, hot days in, for example India, have a significant impact on mortality, especially for each additional day where temperatures rise beyond 35°C.

LEARNING FROM THEHUMAN BODY’S DESIGN

However, given that air-conditioning is also responsible for the release of greenhouse gases, it leaves very little room for developing countries to use critical adaptation tools, like air-conditioning, in an increasingly warming world. As such, the way out of this conundrum for developing countries such as India and China is to search for some form of technological breakthrough to mitigate impacts of global warming.

Studies of how the human body reacts in hot environments could provide some insight into creative engineering design in constructing sustainable dwellings. Normally, the body cools itself by opening pores on the skin and releasing water and salts. As the water evaporates, it transfers the body’s heat to the air. Because water has a high latent heat — which is the heat required for changing liquid to gas — this process usually carries away enough heat to do a good job of cooling the body.

This “technology” has already been adapted in food storage to reduce wastage by the creators of the Evaptainer, a storage device that uses evaporative cooling to store food, without the use of electricity. Similar technology, albeit on a larger scale, may be the solution to installing air-conditioning in homes with minimum energy consumption.

The sustainable home of the future will need to be built in a way that allows it to withstand extreme temperatures. This is especially important when we address housing needs of the millions in Asia who now have no proper dwellings. Cost is an important factor that is difficult to overcome given the number of houses that need to be constructed.

We suggest upscaling the technology behind Evaptainers by incorporating the technology in housing design. Further research is needed to identify appropriate materials. With design modifications, water can even be replaced with other suitable insulating materials to retain heat during winter.

This technology can, without the use of electricity, act as an effective adaptation tool against temperature extremes. Such building design could effectively function like Evaptainers for residential housing.

Meeting housing demands in the urban centres of Asia is a challenge, especially in terms of cost. This particular design attempts to alleviate the cost to some extent, especially in terms of stabilising indoor temperatures, which could very well make the difference between life and death for some in the future. This would be most effective in public housing or in government housing projects for disadvantaged communities who will feel the brunt of climate change.

This technology could potentially be used for larger commercial buildings with the aim of reducing energy consumption or even in automobiles of the future, like driverless vehicles.

There is a need to provide decent energy-efficient housing to help the millions without proper homes. The impact of climate change make this need even more pressing. Evaporative cooling technology has great potential in meeting this challenge, especially where social needs demand solutions from science and technology.

ABOUT THE AUTHOR:

Christopher Lim is Senior Fellow at the Office of the Executive Deputy Chairman and Tamara Nair is Research Fellow at the Centre for Non-Traditional Security Studies, both in the S. Rajaratnam School of International Studies (RSIS), Nanyang Technological University. This piece first appeared in RSIS Commentary.