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The air-conditioned trap

Henry Miller titled his 1945 book The Air-Conditioned Nightmare, a critique of American culture where "the divorce between man and nature is so complete." Seventy-five years later, air conditioning has become a global trap. Every time you experience discomfort due to the indoor temperature, the reason might be the misuse of air conditioning and the lack of natural ventilation.


Born and raised in a Mediterranean culture – where most of the people's life is spent outdoor – I am used to keeping windows open almost all year long. When I started my life in Japan, I had to get used to a slightly different lifestyle where the people spend most of their time into indoor spaces with artificial climatization. Often, I felt very uncomfortable – and even got sick – due to the temperature shocks. So, I decided to research deep on this topic to understand the motivations and the possible solutions to this issue. A couple of years ago, I even created a joint venture in Japan with the Italian tech company Enerbrain. Together with local partners, I founded Enerbrain Japan in 2018. The company aims to improve financial performance, indoor comfort and environmental sustainability of buildings thanks to deep learning and IoT. I decided to write this article to promote the benefits of natural ventilation against the “aircon addiction” that characterize our present times.


In ancient times, being natural was natural. The definition of “natural ventilation” didn’t even exist because ventilation in the buildings was necessarily natural. Buildings were designed to keep itself fresh in the summer and warm in the winter, thanks to natural ventilation and thermal inertia. Egyptians, for example, hung water-soaked reeds in windows to cool down their homes. Ancient Greeks and Romans used air and water ducts. Chinese invented the fan. Those ancient cultures were the first to develop the principles of “passive solar design”, that is planning the buildings considering their orientation to the sun and their thermal mass. The techniques were practiced for millennia before the advent of mechanical heating and cooling because no other option was available.


Asia was traditionally the cradle of naturally cooling architecture. The Chinese and Japanese house featured multiple sliding walls/doors to change the internal movement of the air, depending on climate situation and needs. Notably, several books and academic publications underline the effectiveness of Japanese traditional cooling techniques. For example, a paper entitled Passive cooling effect of traditional Japanese building's features reveal that natural ventilation, solar shading by a thatched roof and the thermal mass by earthen floor are adequate for interior cooling. Unfortunately, those strategies that have shaped architecture for millennia, today are often ignored. Nowadays, in the majority of the buildings, indoor air is made up of only one-fourth of outside air. The rest is the air breathed the occupants, recirculated and filtered.

“Your building can make you sick or keep you well”, according to a recent article on The New York Times. According to the author Dr Joseph G. Allen of Harvard University, most of the buildings are chronically under-ventilated and can spread diseases. When the outdoor temperatures are extraordinarily high or low, the air in the premises (especially offices and schools) may be all recirculated, thus leading to cross-contamination. To reduce the risk, Dr Allen suggests to dilute airborne contaminants by providing outdoor air ventilation, or at least enhance the level of filtration. Also, the United States Environmental Protection Agency reports that indoor air can contain high levels of pollutants if not regularly exchanged. Experts recommend at least four air exchanges per hour. HVAC systems are used to ventilate, heat and cool the building. The air is filtered and cleaned, but these systems can even act as sources of pollutants in some cases, for example, when the filters become contaminated. To reduce this risk, E.P.A. recommends proper indoor air quality management, including the following:

  • An adequate supply of outside air;
  • Correctly installed and maintained filters;
  • Attentive space planning;
  • Diligent maintenance of HVAC equipment.


During the recent Covid-19 pandemic, people were forced to stay indoors as much as possible. Nevertheless, little consideration has been demonstrated for indoor air quality. Daylight and natural ventilation – as widely demonstrated by scientific publications - can help to stop Coronavirus from spreading indoors, besides lowering energy consumption and supporting human health. “If you want to fight infection, think about opening a window”, reported The Guardian. "Modern hospitals try to kill, remove or constrain pathogens with high-energy systems using air extraction, high-temperature sterilization and ultraviolet, but the low-tech solution of simply opening windows can reduce cross-contamination between patients within, or between, wards". Here is the reason why traditional hospitals were built with high ceilings and large windows. It is demonstrated that infections can be prevented through natural ventilation.

An academic paper titled “Roles of sunlight and natural ventilation for controlling infection: historical and current perspectives” analyzed the so-called "open-air factor" - defined in the 1960s - the lethality of outside air to micro-organisms. "There is some evidence that natural ventilation can be more effective than mechanical systems for preventing transmission. During the 1918 influenza pandemic, sick patients who were accommodated in the open-air survived in greater numbers than those in hospital wards. The highest risk of infection occurred in mechanically ventilated rooms with sealed windows, despite being ventilated at recommended rates. (…) Case studies from China show that cross-ventilation is useful for controlling SARS transmission in hospitals. In addition, isolation wards with a high proportion of operable windows were more effective in preventing outbreaks of SARS among healthcare workers”.

Nowadays, most of the artificial climatization in the buildings is obtained through convective systems.  Air is warmed or cooled and circulated within highly insulated sealed structures. Even though the contemporary buildings offer a better energy performance than the old ones, the lack of natural lighting and ventilation can generate health issues. Before the advent of air conditioning, heating and cooling were simply obtained through natural elements: sun for heating and wind for cooling. Florence Nightingale - founder of modern nursing – supported radiant heating against warm-air heating, because she considered air heated by metal unhealthy.  She believed that convective systems were harmful and prevented or delayed recovery.

With radiant heating, thermal comfort is achieved with lower temperatures compared to convective systems: a significant advantage in terms of energy savings and health benefits. According to the British physiologist Sir Leonard Hill (the 1920s), the human body needs the stimulation of a continually changing environment. Thus he recommended sunlight, fresh air and radiant heating. These recommendations are confirmed nowadays by the theories of biophilic design. Radiant heating is a useful technology for heating indoor and outdoor spaces, and the sunshine is the most common example. The heat is emitted from a warm element (floors, wall or ceiling) and warms the space without heating the air. Humanity has used radiant heating and cooling since very ancient times. Radiant cooling is the opposite. Cooled surfaces are used to remove the heat through the radiant exchange, again without cooling the air.


Besides the health risks described so far, we all need to stop our addiction to air conditioning to slow global warming. To conquer our indoor spaces, manufacturers and electricity corporations convinced us that air conditioning is a necessity rather than a luxury. We wake up every morning in a climatized home, enter in the car, reach the office, go for shopping in a mall and go back home without even notice the world outside and the incredible variability of nature and the seasons. We have become used to live in artificial spaces, with a synthetic "ideal" temperature. Is this acceptable? Or we need to rethink our modern lifestyle?


A recent experiment in Manhattan found freezing temperatures in almost all the luxury stores: the higher the prices, the lower the temperatures. Same in Asia, where several studies have demonstrated the same incredible trend. “Shivering for status: when cold temperatures increase product evaluation” is a recent Japanese academic paper on this topic. The research "propose and demonstrate that physical cold can indeed increase consumers' perceptions of a product's status signalling and luxuriousness." Hong Kong leads this trend with its malls, that make up 60 per cent of the city's energy use in the summer. A book published in 2014 – “The bling dynasty: why the reign of Chinese luxury shoppers has only just begun” – confirm these findings. Author Ewan Rambourg explained that A.C. is "Air conditioning is chic, it’s luxury, it’s a sign of wealth". Besides the ridiculous circumstance of wearing winter clothes in the summer, this insane addiction to cold air creates enormous damages to the environment. An interesting article on The Guardian describes this "air conditioning trap", the vicious circle that is heating the world. The more we use aircon, the warmer it gets outdoor. “It’s not a matter of going back to the past. But before, people knew how to work with the climate,” says Ken Yeang. “Air conditioning became a way to control it, and it was no longer a concern. No one saw the consequences. People see them now.”


What if we all reduce (or altogether avoid) the use of air conditioning in our cities? The natural cooling architecture was typical in traditional Asian cultures. Take Japan, for example. Before the use of air conditioning systems blowout in Japan, traditional buildings were designed to adapt to climate conditions and seasons. Ventilation was simply obtained by opening sliding walls and windows in the summer. Through the use of patterns and spatial layering, Japanese vernacular architecture provided a connection with nature while offering thermal comfort. In my book “Patterns and Layering: Japanese Spatial Culture, Nature and Architecture” – edited with Salvator-John Liotta and Kengo Kuma – I have described how the use of layered boundaries (kyokai), movable walls (fusuma and shoji), and natural materials guaranteed thermal comfort while maintaining a secure connection with nature. 

An interesting academic paper of 2007 - "Thermal comfort in the traditional Japanese house" -  investigated how "a house with large opening surfaces, no thermal insulation and very low environmental impact can become a valuable shelter during cold winters and hot, humid summers", thanks to a high degree of flexibility of the external envelope. The study also underlined that environmental performances of a building are strongly connected to the socio-cultural context in which it is built. Namely, humans can adapt to climate conditions and seasons: human comfort is adaptive, not objective.

Humans can adapt to different temperatures and outdoor climate influences indoor comfort: this concept is the base of the “adaptive comfort model". Researches demonstrated that "occupants of naturally ventilated buildings accept and even prefer a wider range of temperatures than their counterparts in sealed, air-conditioned buildings because their preferred temperature depends on outdoor conditions”. Thermal comfort as a "condition of mind" is related to three different types of adaptations: behavioural, physiological and psychological adjustment. In moderate climate zones, the understanding of the adaptive model for thermal comfort and the use of Personal comfort systems can drastically reduce the use of energy for cooling and warming.


Human behaviours can impact the perception of thermal comfort, as well as simple habits from the tradition can contribute to cool the hot summers without relying on aircon. For example, Uchimizu - the Japanese culture of sprinkling water on roads and in front of homes to cool the air – or wearing cotton yukata while eating kakigori or somen. In the aftermath of the March 2011 earthquake, a national movement called Setsuden was born to encourage the Japanese public to conserve electricity. As always happens when calamities occur in Japan, people reacted with choral enthusiasm and collaboration. The use of aircon was drastically reduced for an extended period, but unfortunately, it fully resumed after a while. During the recent pandemic, the Japanese government called for the adaptation of the"3 C's" concept: avoiding Closed spaces with poor ventilation; Crowded places; and Close-contact settings. Several shops, following the government advice, started to open the doors and windows, thus prompting the people to rediscover the benefits of natural ventilation. 


Could low-tech design prevent climate change-influenced pandemics? It is the question raised in a recent article of the American design company Gensler. Dis-conditioning and natural ventilation are the keywords to rethink the possibilities of building technology and its relationship to nature. Luckily, examples of low-tech design are becoming frequent in Asian countries. Some Japanese architects and design firms are experimenting with low-tech design and recovering traditional techniques to control climate.


Ryuichi Ashizawa – for example – recently designed a house in Okinawa that "characterized by respect towards the natural environment, and maintaining harmony between man and nature." Several traditional techniques are adopted here to create a flexible and responsive environment that use natural elements to guarantee thermal comfort with low energy consumption. Another virtuous country is Vietnam, where young and dynamic offices are recovering traditional techniques to enhance natural ventilation. Vo Trong Nghia Architects - among the most renowned offices in Vietnam – often adopt bamboo as the new ‘green steel’. V.T.N. designed several iconic buildings, incorporating passive solar strategies and flexible partitions to promote or suppress cross-ventilation. Says Trong Nghia, “If all the people on Earth – seven billion people – start to use energy for furious development, the Earth would not be able to sustain nature and human activities any longer. Our mission is to create buildings that consume less energy and can return green to the Earth.”

In modern times, being natural must be natural again.