Using air conditioners only worsens global warming; it is possible to achieve climate benefits with alternative air conditioning systems. That was recently the message in the first part of an interesting series i NRC about the air conditioner: The world can no longer do without air conditioning – soon there will be 4.5 billion (16/7). The article is based on the inevitably increasing demand for the use of air conditioning systems. But much can be done about that issue. Although of course you all want an air conditioning system in areas with prolonged heat of 40°C or higher. However, there are great risks with the use of air conditioning, not only for the climate, but also for our health and resilience.
Over the decades, our indoor climate has become increasingly tight. This applies in winter, but also increasingly in summer. This is partly due to the technical possibilities, such as the availability of air conditioning, but there is also an important role for the comfort models used in the construction. The most widespread comfort model, which dates from the 1970s, assumes that a thermally neutral state (thermoneutral is defined in the model as the perception of the ambient temperature as neutral) provides the most comfort and that this is the same for everyone everywhere in the world. The model is part of international guidelines and has resulted in indoor climate requirements with a narrow temperature range.
There is also the so-called adaptive model. This describes that in naturally ventilated buildings, where individual control of the temperature is possible, one accepts much greater temperature variations and feels even more comfortable than in centrally controlled buildings with air conditioning. In the tropics, for example, much higher temperatures are accepted, while acceptance and comfort in temperate regions depends on the season. In other words, the body adapts.
Question mark at constant temperature
The adaptive comfort model has been reasonably accepted for the last fifteen years and is also included in the standards. Nevertheless, in practice, a constant indoor climate is generally assumed for a so-called average person. This conservative attitude stems in part from the installation industry and building contractors, who have become accustomed to strict regulation. But the building managers and finally the users’ expectations also play a role.
Scientific research into human physiology, health and the perception of comfort questions the usefulness of a constant and fixed setting of the indoor temperature. Results from, among others, Maastricht University show that more variation in temperature and exposure to both cold and heat results in a metabolically healthier body. There are beneficial effects on fat and sugar metabolism and also on the heart and blood vessels. Regular exposure to heat and cold also makes the body more physiologically resistant to extreme heat and cold. The research shows that even mild temperature variations provide these benefits. Acclimatization takes place after a few days to a week. Heat acclimation, for example, increases sweat capacity and allows for cardiovascular adaptations.
A change in the ambient temperature is essential for our resilience and for our health. You can call it a natural temperature training. Since we spend about 90 percent of our time indoors, a dynamic indoor climate is desirable that moves much more in step with the temperature outside.
Also read: Air conditioning? The French have other methods of dealing with the heat
To get used to cooled room
However, we see the opposite happening. We are getting more and more used to temperatures of around 20°C. The use of air conditioning worsens this process in the summer. Over time, you can no longer sleep in the heat or concentrate on your work. It is also nicely described in the article from the air-conditioning series about India, where Nidhy Aneja, a secretary at an IT company in New Delhi, says: “I would rather not even be on the street anymore. I just go from cold room to cold room. Your body gets used to it and then you don’t want to go back.” (NRC7/18)
Very extreme climatic conditions and vulnerable population groups may require air conditioning, but for the Netherlands with the hotter summers as they occur more and more and as we used to love going on holiday to France, our advice is: instead of avoiding heat from use of air conditioning, we should expose ourselves, albeit to a reasonable degree, to heat. In temperate regions, this means that you would prefer not to install air conditioning at home and use cooling very carefully in office buildings. That way, you kill two birds with one stone: healthier and more robust people and energy savings.