Protecting students’ health through thermal environment surveys and implementation of measures for dealing with extreme heat conditions

Date of interview	June 16, 2022
Interviewee	Dr. Takashi Nakaya Assistant Professor, Department of Architecture Faculty of Engineering Shinshu University

Could you give us an overview of your research work?

The original area of my research focus has been architectural environmental engineering, which is grounded in physics. So I have been conducting studies on the thermal environments of building structures and the evaluation of their energy consumption. The study of human behavior to adapt to hot weather has been my primary interest, in terms of how much heat we humans can endure and what types of reasonable behaviors we engage in, depending on the temperature. My research also covered some irrational aspects of human behavior in dealing with high heat conditions. In recent years, the focus of my study shifted to the thermal thresholds beyond which humans would turn on their air conditioning and electrical fans, as measured by temperature and humidity, for both hot and cold.
After that, the scope of my research expanded to include studies on cooling and heating appliances as implemental means of adaptation, and also studies on the thermal insulation and shading performance of buildings as architectural means of adaptation. Meanwhile, as climate change has become such a crucial topic, I’ve always wanted to take on studies that deal with it.
Then, I was invited to partake in a research and development project focusing on the topic, which was supported by the Environment Research & Technology Development Fund FY2019, and started conducting my broadly-based research on building renovation planning and building performance requirements that might be applied in the future.

Could you give us some specific examples of your research activities?

Between FY2019 and 2021, I led a research project involving schools based in Nagano Prefecture that studied the schools’ thermal environments and subjective assessment of high heat conditions, and created a set of criteria that their students could use to determine whether they were suffering from hyperthermia.
While Nagano Prefecture is generally thought of as a place with cold weather, the temperatures here do rise to the levels where the risk of hyperthermia onset arises, in the classrooms of high schools without air conditioning. This indicates that the dissipation of human body heat has its limits only involving natural ventilation, heat radiation, and electrical fans.
Furthermore, while people are able to achieve thermal comfort in the temperature range from 20C to slightly below 30C by putting on or taking off their clothes, social constraints prevent them from taking off more clothes beyond that point. In other words, adaptation to high heat conditions by adjustment of the amount of clothes that one wears has its limits.

So after that, I ran a study involving elementary schools, where a survey was conducted of the students and their teachers that asked them how hot or cold they felt in the room temperatures and analyzed their responses. The analysis then found that the students’ perceived room temperatures and heat conditions varied noticeably by grade and sex, and that the students in the higher grades tended not to report it even when they felt hot.
In this study, the teachers − who were in charge of air conditioning to adequately cool their classroom temperatures − were also asked to predict whether their students were feeling hot or not in the given moments, and it was revealed that the teachers’ prediction and the students’ perception were asymmetrical. One of the likely causes of such asymmetry is the disparity in activity volumes and thermal capacity between adults and young children, and also the fact that the teachers tend to be in the area of the classroom near the blackboard where the temperature is relatively cool. As the area by the windows in particular is where the temperature tends to rise the most, it would be difficult for the teachers to estimate how the thermal perception of their students might be that are there.

What other issues have you identified in your research besides inside the school buildings?

Depending on how they are arranged, schoolyards can have hot spots also. I encountered some cases where the southern edges of the schoolyards had the highest heat conditions due to the direct sunlight to the ground, combined with ground reflection and building reflection.
Meanwhile, as the meteorological observatory being operated by Nagano City is located at a somewhat higher elevation, the temperature data reported by the facility tend to be lower than the temperatures measured at various schools across the municipality. These disparate temperature readings caused by the different elevations of the observatory and the schools, which can occur even on the same premises, indicate the importance of measurement.

Please tell us how climate change is particularly impacting schools and other educational institutions in terms of recent hyperthermia risk trends.

The risk of hyperthermia inside buildings has apparently been rising. According to the standard meteorological data reported by Nagano City, the temperature in August typically fluctuates between the low 20s and low 30s in C, the future prediction (RCP8.5) of the climate for the municipality estimates that the average temperature of the month might increase to the range from 25℃ to slightly below 35C in 2050 while the highest temperature could rise from the current level of around 30C to nearly 40C by then.
As the surface temperature of the human body is about 33 to 34C, if the external temperature surpasses it, the heat dissipation from human bodies could be reversed, resulting in heat transfer to the bodies. To address this risk, it is crucial to implement thermal insulation on buildings and renovate them to improve their shading performance.
In terms of hyperthermia incidences at schools today, roughly 5000 cases of hyperthermia are reported each year, encompassing kindergartens to high schools. Hyperthermia occurs especially during exercise activities. However, as some of those hyperthermia cases get diagnosed with poor physical condition, the actual number should be even higher.

Please tell us about the measures currently being implemented as well as measures that should be implemented in the future to adapt to the effects of climate change.

In terms of mitigative measures, it is desirable to reduce the energy consumption used for air conditioning, so high expectations are placed on the adjustment of human behaviors to better adapt to climate change. But because such approach entails health risks, it is necessary for us to be cognizant of the limits of this type of adaptation and promote the use of air conditioning as needed.
As I explained a moment ago, adults and young children perceive varying degrees of heat differently, and the perceived room temperature changes depending on the area of the classroom. Therefore, it would be ideal if when to turn on air conditioning in classrooms could be managed numerically, using measuring instruments, for thermal environment optimization, instead of relying on the teachers’ subjective determination. This in turn will lead to reducing the teachers’ managerial responsibility.
However, if an alert of any imminent heat risk is issued in the form of a sounding bell, etc. while class is in session, that would be disruptive. To work around this issue, I have developed an IoT device with experts specializing in electronic control that can communicate heat stress signals in a non-disruptive manner. The device is comprised of an LED strip that can be attached above a blackboard, which turns orange when the WBGT exceeds 28C. After our one-year trial of this device, we conducted interviews with the teachers that used it and received generally positive responses, citing instances of its efficacy as a sort of communication tool, with students actively informing the teachers when the temperature rose past 28C.

Meanwhile, as you mentioned a moment ago, the approach to addressing climate change with emphasis on energy conservation is also essential, correct?

For both summer and winter, there is a tradeoff between the reduction of electricity costs by using less air conditioning and heating and the rise in health risks. Therefor, one of the important measures we should consider implementing in the future is thermal insulation of buildings.
In winter, we should take in the solar energy through the windows as much as possible while maintaining the internal air that gets heated during the day, through the enhanced thermal insulation of the walls and windows to save the heating cost. Reversely, to reduce the air conditioning cost in summer, we should reduce the solar energy that comes through the windows and if the room temperature becomes higher than the external temperature, it is advisable to ventilate the room. In other words, the optimal window specifications change diametrically between summer and winter. This poses a challenge that must be overcome through our research.
So to address it, we have been conducting a study that entails calculation of all possible parameters and statistical muti-objective optimization to identify building performance characteristics and operation techniques suitable for each region and season. When elementary school buildings are demolished and rebuilt now, their usable lifespans could possibly reach the year 2100, and the temperatures will likely have risen to significantly higher levels by then. With that in mind, I intend to conduct research on the shapes of buildings that are optimized for keeping the room temperature from rising, which will also incorporate passive building designs and be the main focus of my research.

Please tell us what you think the key challenges are that must be addressed in the coming years as well as your outlook on the future.

For us to develop buildings that are safe and consume only small amounts of energy, we need to extract essential information for the thermal analysis of architectural structures from future prediction data, and apply the obtained insights to develop various building specifications, while researchers in each region must also conduct analyses and studies on their own specific to their local environments. While information processing technology is one of the key issues that needs to be addressed, I believe the use of future prediction data will progressively advance and be applied to building designs in the future.

Please tell us about the source of motivation for your research activities. Also, if you have any message for students aspiring to become researchers in your field, please share it.

Architecture is a study and practice that subsume different disciplines and components, including philosophy, ideologies, designs, structures, equipment, and environment. It is a holistic academic discipline that entails research from wide-ranging perspectives, because the optimal modes of living vary across the age continuum. While each researcher has a duty to pursue mastery in its area of specialty, interdisciplinary research is crucial in architecture as it is related to climate change, global warming, and many other issues that are all interconnected.
While my previous research focused on indoor human behavior and modes of living, my recent involvement in studies related to climate change has broaden my horizons and allowed me to partake in a topic that positively impacts all humanity while communicating with people representing vastly diverse fields. So that’s a great motivation for me. And I would be pleased to see many new researchers join this field of architecture that studies climate change with such grand perspective.