Air-conditioning: The cold reality

The Earth is running a fever. So with summers growing hotter (and with affluence rising) year by year, our world is becoming more and more dependent on air-conditioning. The possibility that air-conditioning could go universal has, in turn, raised ecological alarms, prompting a scramble for more eco-friendly cooling.

The United States military, for instance, is being praised for aggressively pursuing alternative energy development and energy conservation. The latter has included spraying foam onto soldiers’ tents in Iraq and Afghanistan in order to reduce expenditures on air-conditioning. The foam is credited with saving $1bn worth of the diesel fuel that runs the generators that power the air-conditioners. But how much energy has really been saved by insulating tents in Iraq, when, for at least six years, a solid majority of those in the US have believed that the war there was all a big waste from the very beginning anyway? And what purpose does energy efficiency serve when it supports the war in Afghanistan, a bloody venture that only 27 per cent of US citizens and fewer than one-third of Afghans believe is worthwhile?  

In a more peaceful realm of human endeavour, solar power is being used, or soon will be, to air-condition airport terminals that serve a wide variety of cities big and small around the world, from Munich to Kuwait to Adelaide to Nantucket. This too is said to be saving energy and reducing greenhouse emissions. But what about the net impact? These facilities are enabling air travel, which is the fastest-growing source of emissions from transportation. Passenger volume is expected to continue growing at its current rate of five per cent a year, and that will cancel out both gains from any number of solar-cooled terminals and expected improvements in aircraft fuel efficiency. As a result, overall emissions from air travel are expected to grow at an alarming two to four per cent per year in coming decades.  

The power-hungry air-conditioner

There are many more examples of energy-efficient technologies being deployed across the globe and, paradoxically, bringing with them increased energy use and greenhouse gas emissions. The biggest leaps in energy use come in the summer months. Largely because of increasing use of air-conditioning, electric utilities worldwide have struggled to satisfy record demand through the torrid summers that have become ever more frequent in recent years.

In the United States, consumption of energy for air-conditioning homes and vehicles has more than doubled just since the mid-1990s. In India, total consumption for air-conditioning is projected to climb as much as ten-fold over the coming decade; air-conditioners already reportedly account for a staggering 40 per cent of all electricity consumption in the city of Mumbai. In Brazil, air-conditioning demand has more than tripled in just five years, contributing to a surge in electricity consumption. Unusually steep increases in electricity demand in southern European countries are being blamed on the proliferation of air-conditioning.

The greatest irony, of course, is that by chilling the indoor environment today, we are helping ensure that future summers will be even hotter. Air-conditioning’s massive energy demand is overwhelming efforts to reduce greenhouse gas emissions. Take the output from all of the United States’ renewable electricity sources combined, multiply it by five, and it still could not satisfy current air-conditioning demand – let alone serve other uses. The US department of energy projects that wind, solar, geothermal, and biomass electricity generation will indeed expand almost fivefold, but not until 2030. By that year, if the department’s predictions hold, total electrical generation from all renewable sources will be sufficient to satisfy only 75 per cent of air-conditioning demand. For everything else, there will be no green alternative.

Better energy efficiency alone cannot reduce the weight of an air-conditioned society. US home air-conditioning units in service today are an impressive 28 per cent more efficient on average than they were in the mid-1990s. But we have taken full advantage of that cheaper comfort, and as a result, the number of kilowatt-hours of electricity used for cooling the average air-conditioned household actually increased by 37 per cent over that same period. This carries on a trend that has persisted since before the industrial revolution: more efficient technologies are cheaper to use, so naturally, we use them more.

And because energy efficiency is a powerful economic stimulus, we take advantage of it not by doing the same with less, or by doing more with less, but by doing more with more. Thus we have everything from foam-covered tents to amazing, and amazingly cooled, football stadiums to air-conditioned dog houses. Increases in society-wide energy efficiency are almost always accompanied by rising, not falling, energy consumption.

Chilling encounters at work

In the United States, any suggestion that we reduce our dependence on air-conditioning meets especially strong resistance from the business world. The foremost reason is that almost every one of the country’s office buildings is designed to be largely uninhabitable in summer without artificial cooling. You can have a tightly sealed building with optimum energy efficiency for air-conditioning, or you can have a highly efficient naturally cooled building, but they can’t be the same building. Although the green-construction industry has come up with compromise designs that can shift between natural and artificial cooling, they are optimum for neither.

Writing in 2010, just as an intense heat wave was suffocating the US east coast, I attempted to envision a future Washington, DC, that would be no longer dependent on air-conditioning. I did not expect this to sit well with the business community, and it didn’t. In one of numerous hostile responses, Conn Carroll of the right-wing Heritage Foundation wrote: “Doesn’t the AC-free enviro-dream world sound wonderful? Daily summertime siestas, shorter business hours, even some days completely off!” But, he warned, “as with all enviro-leftist schemes, the heavy costs of their low energy utopian dream are being ignored. Slower workdays mean less productivity. Shorter hours and closed offices mean lost profits for employers.”

Carroll need not have worried quite so much. The scientific literature is brimming with studies showing that increased ventilation with outdoor air, faster air movement, greater control over conditions in employees’ personal workspace, and more contact with the natural environment all improve productivity at both work and school. Nevertheless, there is a widespread belief among employers that their employees are like computer chips, operating most efficiently when kept as cool as possible. Research does indeed show that people work most productively when they’re not feeling excessively hot, but it also shows that the typical office’s too-cool conditions are a drag on productivity.

The standards that are followed in the cooling of most buildings do not account for the fact that the temperatures that we humans find comfortable don’t lie within a fixed range. Rather, our comfort range shifts up and down, and expands and contracts, depending on the indoor and outdoor temperatures we’ve experienced in recent days and weeks. This phenomenon, called the “adaptive model of comfort”, explains why people who typically live and work in air-conditioned spaces have different comfort expectations from those who do not.

Such adaptation was seen, for example, when a group of office employees in Thailand – half of whom worked in air-conditioned spaces and the rest of whom worked without air-conditioning – were surveyed about their comfort under a variety of temperatures under experimental conditions. Eighty percent of non-air-conditioned workers remained comfortable at temperatures as high as 32 degrees Celsius, if ventilation was adequate. Only 20 per cent of typically air-conditioned workers were comfortable at temperatures that high.

The not-so-great indoors

Those countries around the world that still have a low degree of dependence on air-conditioning should think twice before moving toward the United States’ industrial comfort standards. Energy consumption is not the only burning issue. The cool, still, dry atmosphere of the standard US home or office has a variety of other unpleasant and sometimes hazardous side effects.

Obviously, air-conditioning can play an important role during killer heat waves like those that struck Chicago and other parts of the United States in 1995 and much of Europe in 2003. But keeping vulnerable members of our communities alive during heat emergencies is one thing; using that as an excuse for neglecting horrible urban living conditions while at the same time tolerating the routine, lavish deployment of chilled air throughout much of the rest of society is another.

Air-conditioning creates a need for more air-conditioning. Human-physiology studies show that life in the world of “coolth” undermines our natural adaptation to heat and can disrupt endocrine functions. As we primates evolved in hot climates, nature equipped us with heat-adaptation mechanisms. Experiencing high temperatures, especially when we are also exerting ourselves, builds up tolerance to heat, and we are able to function and work for longer periods under higher temperatures. Without such heat adaptation, our bodies are far more susceptible to heat.

Meanwhile, extremely tight, well-insulated buildings often suffer from so-called sick building syndrome. It is estimated that a productivity loss of as much five to 13 per cent is “built into” well-buttoned-up, energy-efficient buildings, even when they adhere to international environmental standards. No single factor, such as buildup of a specific pollutant, accounts for the wide range of problems associated with the air-conditioned environment. The causes are many and varied.

Depending on the extent of outside ventilation, toxins and irritants can be ten to 100 times as concentrated in indoor air as they are outdoors. Researchers in Brazil, the United States, and Europe have found that people who are employed in air-conditioned workplaces visit doctors and hospitals more frequently and generally have a higher risk of poor health than do those who work without air-conditioning.

An air-quality expert commenting on such studies has written: “Occupants of office buildings with air-conditioning systems … consistently report, on average, more symptoms in their buildings than do occupants of buildings with natural ventilation. This has been the finding from many studies over the last 20 years … the symptoms in these studies have included mucous membrane irritation, breathing difficulties, irritated skin, and constitutional/neurological symptoms such as headache and fatigue.”

Meanwhile, ventilation is known to be inadequate in a large share of US schools, which have been a major growth area for air-conditioning in recent years. Volatile organic compounds, moulds, and allergens trapped in classrooms have been fingered as prime suspects in causing respiratory problems for students. A range of studies worldwide have linked poor ventilation and poor school performance.

The range of research findings that favour increased flows of outdoor air is remarkable. Under natural ventilation, people have been found to experience fewer problems with headaches, colds, other respiratory ailments, circulation problems, eye dryness, allergies, and chest tightness. There is lower absenteeism when employees work near windows and can open them.  

When faced with the spring and summer onslaught of pollen, dust, and other allergens, millions of allergy and asthma sufferers take refuge in the climate-controlled indoors. Yet the air-conditioning era has seen rates of allergies skyrocket in Western societies, and the prevalence of asthma has doubled with each decade that passes. The still-evolving “hygiene hypothesis” says that the immune systems of allergy and asthma victims have been disoriented in part by insufficient childhood exposure to bacteria, fungi, nematodes, and/or other organisms. It appears, thanks largely to air-conditioning and electronic entertainment, that youngsters are not getting enough exposure to the more benign microscopic inhabitants of the outdoor environment, especially the rural environment.

If we are ever to gain some control over fossil fuel consumption and greenhouse emissions, a massive worldwide adjustment of thermostats will be required. But most importantly, we’ll need to adjust our own internal thermostats. By taking a more flexible attitude toward comfort and finding alternative ways to make the indoor environment livable, we can not only save energy but also become more resilient human beings. And we will need that resilience. The coming decades will test our ability to adapt and create, and we cannot leave it to technology to bail us out next time.

Stan Cox is a senior scientist at The Land Institute in Salina, Kansas, US and author of Losing Our Cool: Uncomfortable Truths About Our Air-Conditioned World.