Thermal comfort is a crucial environmental factor that is often overlooked in schools. In fact, officials in a Michigan school district estimated that 60% of schools in their district do not have air conditioning, which required some schools to temporarily adjust their schedules due to extreme heat in 2019. This article explores the impact that poor thermal comfort can have on the health and well-being of students, teachers and staff and why schools must prioritize it.
Why Is Thermal Comfort Important?
Our thermal environment is important not only for our comfort, but also for our health. Our bodies have a basic need to thermoregulate, or maintain a constant internal temperature within a specific range. If the indoor environment is too hot or too cold, this can be a challenge. Below are three key reasons why school administrators need to take into consideration thermal comfort when working to create healthier school environments.
1. Hot/Cold Temperatures and High/Low Humidity Can Be Detrimental to Health
Cold indoor temperatures have been linked to respiratory and cardiovascular problems, including increased blood pressure and asthma symptoms, as well as poorer mental well-being. Hot temperatures can be similarly detrimental. A generally accepted ideal thermal environment ranges between 68-79°F (20-26°C).
Furthermore, high humidity may result in greater thermal discomfort due to increased friction between skin and clothing caused by increased sweat production. Low humidity, on the other hand, has been associated with the development and exacerbation of respiratory symptoms such as asthma and irritation of the eyes, nose and throat. The U.S. Environmental Protection Agency (EPA) recommends that schools keep indoor relative humidity (RH) levels between 30 and 50%, or at minimum, under 60% RH.
2. Children Are More Vulnerable to Temperature and Humidity Extremes
Young children have higher metabolic rates, higher core body temperatures and are less able to regulate their body temperatures compared to adults. Thus, they are more vulnerable to the effects of extreme temperatures and ambient humidity levels.
Additionally, children in pre-K and kindergarten may have difficulty expressing their thermal discomfort and are less able to adapt to their thermal environment by adding or shedding layers of clothing and/or requesting temperature adjustments.
3. Classroom Temperature Affects Student Performance
Both temperature and humidity greatly influence thermal comfort. Students cannot perform at their best if they feel too hot or too cold. Studies have consistently shown that children prefer cooler environments and are particularly vulnerable to the effects of higher temperatures, which in turn can impact their performance in school. In fact, higher classroom temperatures have been associated with lower test scores and reduced cognitive speed.
How Does Temperature and Humidity Impact Thermal Comfort?
Indoor air temperatures can greatly impact the thermal comfort and performance of students in schools. For example, a study of 75,000 high school students in New York City found that students were 12.3% more likely to fail an exam on a 90°F (32°C) day versus a 75°F (24°C) day. Another study linked daily local weather data to the test scores of 10 million high school students across the nation and found that hotter school days were associated with reduced test scores, with extreme heat (temperatures above 90°F (32°C)) being particularly damaging. The study also found that, in schools without air-conditioning, a 1°F (0.56°C) hotter school year was shown to reduce that year’s learning by one percent.
Unfortunately, many schools are not equipped with functioning HVAC systems or operable windows (or lack windows in classrooms altogether) that can help mitigate extreme temperatures. In fact, one study found that student performance on arithmetic and language-based tests were shown to improve significantly, specifically in terms of speed, when classroom temperature decreased from about 77°F to 68°F (25°C to 20°C). Based on these results, the researchers calculated that reducing classroom air temperature by 1.8°F (1°C) could improve student performance speed by about 4%.
Avoiding extreme humidity levels can help control mold, dust mites and pests – along with related health issues – while also providing thermally comfortable conditions for students, teachers and staff.
Students are not the only ones who can benefit from optimal RH levels. Prolonged exposure to high (>50%) or low (<30%) classroom RH has been associated with an increased risk of asthma and cold/allergy symptoms among teachers, suggesting a cumulative effect of indoor RH on health.
2 Ways to Improve Thermal Comfort in Schools
1. Ensure Reliable Heating and Cooling Systems
Investing in reliable heating and cooling systems in schools is essential for creating thermally comfortable environments and improving overall health of students, teachers and staff.
2. Install Humidifiers and Dehumidifiers
Investing in humidifiers or dehumidifiers can help to maintain optimal humidity levels, thereby helping provide a thermally comfortable environment.
Schools should consider installing a whole-building humidification/dehumidification system, which is a (de)humidification unit that is installed into an HVAC system, or the use of portable (de)humidifiers. While opening windows can also help to adjust humidity levels, it may not be feasible during extreme weather conditions such as summer or winter.
Thermal Comfort for Students and Staff
Ensuring that students, teachers and staff are satisfied with their thermal environments is crucial in helping to avoid health-related issues associated with temperature and humidity extremes. Furthermore, the overall discomfort and health-related issues that arise due to poor thermal environments in schools have been shown to greatly impact student performance and health of both students and teachers. Schools must work to identify and address issues related to thermal comfort to ensure that everyone in the school is satisfied and comfortable all year round. Work with us to make your school a healthier and more effective learning environment.
For more information on indoor environmental factors that affect student health, well-being and performance and steps that schools can take to address these factors, make sure to check out our white paper, Healthy Learning Environments.
Contributors: Bing Bing Guo, MPH and Carolyn Swope, MPH