Reinventing Comfort: The Close Comfort Portable AC
Let’s recap. The global air conditioning industry emerged from the 1960s with an “ideal” comfort temperature for American businessmen, and that mostly explains why office buildings, hotels and so many apartments and homes in tropical countries like Singapore feel so uncomfortably cold.
Recently, building scientists have been rethinking the idea of comfort. Some have been busy measuring the actual temperatures people live with and feel comfortable. Real measurements reveal people living comfortably in temperatures ranging from 10°C to about 33°C. Using appropriate clothing, food, buildings, wood-burning fires, and low-energy cooling appliances like fans, large numbers of people go about their lives without worrying about how cold or hot they feel. Part of this is adaptation: the human body acclimatizes to cold or hot weather in just a few days. Thousands of years of adaptation extends this range: Eskimos and Australian aboriginal people have evolved unique physiological adaptations to their living environments. In even more extreme temperatures, people move to cooler or warmer places in a building. The image below shows a home with a wind tower in Iran - an ancient style of achitecture particularly well adapted for extreme heat in summer and cold in winter.
However, if people live and work in air-conditioned buildings and move in air-conditioned cars in modern cities, they lose their ability to adapt to heat and cold. They even prefer cooler indoor conditions in summer than winter!
Recent physiological evidence is revealing health effects that go far beyond the familiar “sick building syndrome”. People living with near constant air conditioning have reduced metabolic function, significantly poorer cardiovascular health, and less thermal resilience, ability to cope with high or low temperatures. Along with this go significantly higher risks that they will need hospital treatment or even die in heatwaves.
As we become more dependent on variable renewable energy sources like wind and solar, it is becoming more difficult to guarantee the reliability of power grids. Recent architectural trends have resulted in far too many people living in buildings where an extended power failure during a heatwave could result in tens of thousands suffering from heat stress with unacceptable risk of mortality. Even without power failures, the 2009 heatwaves in France caused around 13,000 deaths in Paris alone. We need to reduce the use of traditional fossil fuels and use more renewables. Global temperatures are rising and exceptional heat waves are becoming more frequent. Therefore the health risks from heatwaves are steadily increasing.
Unfortunately, while we know how to design buildings that can provide a safe living environment through heat waves without air conditioning, the knowledge is only spreading slowly among architects and building designers. The newly reconstructed Architecture School at the National University of Singapore uses a new approach for designing public buildings with near zero energy needs. The air conditioning provides air with much of the moisture removed at a much higher temperature than would be considered feasible in conventional buildings, around 28°C. Ceiling fans circulate the air with the result that people feel comfortable in much warmer air. Solar panels on the roof provide most of the energy needed to remove the water from the air using conventional air conditioning machinery. Hopefully a new generation of Singapore architects will build on these ideas in coming decades.
Unfortunately it’s hardly practical to demolish and rebuild hundreds of millions of buildings in cities everywhere. Most of us will be stuck with the buildings we have today as the climate warms in coming decades.
Close Comfort Portable ACsClose Comfort air conditioners can solve many of these problems. Because Close Comfort provides a localized cool microclimate, users are exposed to the prevailing heat from time to time. Experience shows that intermittent exposure to eve extreme heat, 40 - 46°C is quite bearable if one can retreat to a ‘cool corner’ to recover. Therefore, people using Close Comfort are less likely to lose their adaptation to heat, resilience and cardiovascular function. (In time, no doubt, research will tell us just how much adaptation Close Comfort users retain.)
Of course Close Comfort will work fine in existing buildings, whether they were intended to be air conditioned or not.
Modest low-cost solar power systems could provide sufficient power to keep Close Comfort portable ACs running in the event of major power failures. While such systems are becoming common in countries where power interruptions are routine, solar inverters used in developed countries like Australia will not run without mains power to synchronise their AC output: a change in inverter technology and most likely building or sub-district storage batteries will be needed for real energy resilience.
In some regions like South Asia and the Middle East building temperatures indoors remain over 35 - 40°C day and night through the summer. This is particularly the case with buildings constructed in the last few decades. People with the freedom to move to lower floors for much of the day and sleep on the roof at night can avoid extreme temperatures. However many people lose that freedom by moving to modern apartment buildings: a sheer necessity in crowded mega-cities. That explains why demand for air conditioning is growing exponentially in countries like India. It’s simply a necessity to survive the heat. Without enormously expensive batteries to store solar electricity, Close Comfort is currently the only feasible air conditioning solution that provides a path to reduced reliance on fossil fuels. Close Comfort was designed specifically for these conditions. Not only can we reduce greenhouse emissions by switching to Close Comfort, users end up far better off financially. Users in Pakistan tell us their energy bills, just for an air conditioned bedroom, fall from about USD 250 monthly to about USD 15, a huge saving.
Close Comfort Portable ACs represent the future of air conditioned comfort for most of us. Exposure to full-on heat for part of the time not only brings financial savings, but significant health benefits as well. A little discomfort goes a long way.