All-year round, your HVAC system is working hard to maintain a steady and comfortable temperature. But, did you ever stop to ask yourself why it matters?
Whether it’s your passengers escaping the weather or the dedicated drivers and staff on board from morning till night – they expect a pleasant indoor environment. The technical term for this is thermal comfort. In this article, we’re explaining what it is and why it’s important to get right on your fleet.
What is thermal comfort?
Thermal comfort refers to temperatures and environments that are comfortable to live or work in. In other words, your employees don’t feel too hot or cold while at work. The opposite of thermal comfort is thermal discomfort. In other words, your employees do feel too hot or cold while at work. While thermal discomfort doesn’t carry health risks like extreme heat or cold, it can lead to issues with productivity and morale. People working in uncomfortable environments are more likely to feel fatigued, lose concentration or be absent from work. Not only can a comfortable environment on your fleet help protect the health and safety of your employees, it also adds to the quality of your service for passengers.
Thermal comfort and WHS laws
You might be wondering if thermal comfort is a legal requirement. While there are no WHS regulations specifically related to thermal comfort, some experts say it falls within the general expectation to provide a safe workplace. A safe workplace is one that minimises risks of physical or mental harm. If an employer identifies a risk, it is their job to remove it; as much as is practical. This might include limiting the risks of hot and cold temperatures, especially when it comes to extreme heat or cold. Prolonged exposure to extreme heat can lead to heat-related illness; such as dehydration, heat stroke or heat exhaustion. Similarly, being in the cold for too long can lead to adverse health effects; like an increased risk of respiratory issues, such as asthma, colds and flus or sinus issues.
How HVAC can support better working conditions
There are 3 key factors that affect thermal comfort: temperature, humidity and airflow. In indoor environments, all of these factors can be controlled. A high-powered HVAC system is considered an effective control measure that can reduce the risks of thermal discomfort; allowing you to adjust temperatures, reduce humidity and increase airflow.
For example, a unit with both heating and cooling can help reduce hot temperatures in summer and increase cool temperatures in winter. A HVAC system with strong airflow helps distribute air evenly and efficiently. Internal mechanisms, such as evaporator and condenser coils, or fresh air intake can help reduce humidity. Coachair’s range of diesel and electric HVAC units have been engineered for Australian conditions – whether it’s cold and wet in Melbourne, hot and humid in Sydney or the dry heat in Perth. Our products offer long life, low maintenance, predictive comfort control and low power consumption. With a philosophy for Through Life Support, you can rely on our team for spare parts, servicing, technical support and more for the lifetime of your equipment.
Ideal working conditions for indoor environments
While there are no official guidelines for a safe and comfortable work environment, research does tell us a bit more about the optimal conditions for indoor environments.
Recommended temperature
The optimum temperature for sedentary work is between 20˚C to 26˚C. However, large changes in temperature can affect how you perceive them. This means this range is a bit flexible. For example, going from 35˚C outside to just 22˚C inside might feel too cold, while going from only 10˚C outside to 22˚C inside can feel too warm. Setting your HVAC temperature to a little above or below the outdoor temperature can help reduce these effects. In general, any temperature above 18˚C is considered safe and comfortable. It’s also important to recognise that age, gender and certain medical conditions can make people more susceptible to heat or cold. It’s a good idea to talk with your employees for a better understanding of their preferred working conditions. Image: Ideal_Indoor_Conditions_For_Thermal_Comfort.png
Recommended humidity
The ideal humidity levels for an indoor environment are between 40%-70%. Anything below 40% can lead to discomfort or health issues, like dry eyes or sinus problems. Humidity levels above 80% are considered extreme and carry higher risks of developing heat-related illness.
Recommended airflow
Too much airflow can create a cool breeze, while too little makes a space feel stuffy or humid. The minimum airflow rate for comfort indoors is between 0.1 to 0.2 metres per second (m3/s). This minimum rate is suitable for small buses and mini vans, but is likely to be too low for larger vehicles. A city bus or long coach may require airflow of up to 1.0 m3/s or more. High-powered airflow can help with faster heating and cooling, better distribution of warm and cool air throughout your vehicle and better air filtration. Compare Coachair HVAC systems Coachair products have set the benchmark for the modern bus and coach air conditioning market. Our range of HVAC units are compatible with both diesel buses and coaches and zero-emission vehicles; like hybrid, hydrogen or electric. Download our product brochures for complete specifications or contact our team on 1300 BUS AIR (287 247) to discuss HVAC options. If preferred, you can also send an enquiry via the website.
References:
SafeWork, Maintaining thermal comfort in indoor work environments, NSW Government, URL: https://www.safework.nsw.gov.au/resource-library/heat-and-environment/maintaining-thermal-comfort-in-indoor-work-environments, accessed 16 July 2025. World Health Organization (2018), WHO Housing and Health Guidelines: Low indoor temperatures and insulation, URL: https://www.ncbi.nlm.nih.gov/books/NBK535294/, accessed 16 July 2025. Safe Work Australia, Working in Heat – Frequently Asked Questions, URL: https://www.safeworkaustralia.gov.au/safety-topic/hazards/working-heat/frequently-asked-questions, accessed 16 July 2025.