Taras Verkhoglyad
Sales Development Representative, Arloid Automation

Thermal Comfort in Buildings – The Importance of Occupant Comfort

People who are thermally comfortable function better and feel happier. That’s why, whether you manage a hospital, a warehouse, or a hotel, providing a positive thermal experience is critical to the success of your space.

At Arloid, we help buildings of all scales and complexities provide the optimum thermal conditions for occupants. Using pioneering AI technology, we enable building managers to take control of heating, ventilation, and air conditioning (HVAC) systems and deliver peak performance whilst simultaneously reducing energy spend.

In this blog, we provide the ultimate guide to thermal comfort in buildings.

What is Thermal Comfort?

Thermal comfort in buildings describes the state of being neither too hot nor too cold. According to the international standard ISO 7730:2005, it is ‘that condition of the mind which expresses satisfaction with the thermal environment’ and can be calculated using predicted mean vote (PMV) and predicted percentage of people dissatisfied (PPD).

However, achieving satisfaction across the board can be tricky, and it cannot be expressed in degrees. Instead, it requires the intricate control of a range of different factors including temperature, humidity, and airflow. More than that, thermal comfort is subjective – and occupants of a building will experience temperature differently depending on their clothing and activity levels.

The thermal requirements will also vary dramatically across the different zones of a building. In hospitals, for example, aseptic operating rooms, recovery wards, staff kitchens, and consulting rooms will all require their own unique thermal settings.  

The UK Health and Safety Executive states that a building can be said to have achieved ‘reasonable comfort’ when 80% of the occupants are satisfied. Even so, making 80% of people in a building happy is easier said than done.

Factors Affecting Thermal Comfort

Thermal comfort or discomfort is influenced by a range of different factors – both environmental and personal.

Air Temperature

Air temperature is expressed in degrees and refers to the temperature of the air that surrounds the occupants of the building. It can be controlled by heating or air conditioning, or even by opening a window. In the UK, it is recommended that workplaces should have a minimum temperature of 16°C or 13°C if the work involves high levels of activity. The upper limit is advised to be no higher than 30°C.

Radiant Heat

When an object is hotter than the air around it, heat will be radiated. It has a big impact on air temperature, and can be produced by a range of sources including heaters, machinery, and ovens. Human bodies also emit heat, as well as absorbing it from surrounding objects. The sun is the greatest source of radiant heat, and can cause a space to overheat if appropriate measures like closing blinds are not taken.


Humidity refers to the amount of water vapour in the air, and it can vary considerably in indoor environments. It impacts thermal comfort because high humidity can prevent sweat from evaporating from the skin, reducing our rate of heat reduction. More than that, clothing can create humidity within the garment itself – for example PPE. In healthcare settings, PPE can make staff thermally uncomfortable extremely quickly.

Air Velocity

The rate at which air is moving in an indoor environment will have a big impact on the thermal comfort of occupants. Air that is too still can make the environment feel stuffy and even result in built-up odour, whereas high air velocity in warm conditions can cool the environment through convection without any actual change in air temperature.

Personal Factors

As we have discussed, thermal comfort is highly subjective, and personal factors are major influences. The amount of clothing worn can make occupants feel too hot or too cold, even if HVAC is functioning at optimum levels. The level of activity also has a role to play. People carrying out physical work are likely to feel hotter than those who are seated.

More than that, physical attributes like height, weight, age, fitness, and even gender can all impact metabolic heat. Sickness can also make someone feel considerably hotter or colder than other occupants. In setting like hospitals, this can pose numerous thermal challenges as the right temperature for staff will not be the same for patients.

The Importance of Occupant Thermal Comfort in Buildings

Our physical environment can have a significant impact on how we feel. And not feeling at our best can have serious repercussions depending on our purpose within the building.

For workplaces, thermal comfort is of paramount importance when it comes to employee productivity. In fact, research into manufacturing in India found that productivity drops by 4% for every degree temperature rises over 27% unless the work is highly automated. A degree increase in 10 day temperature averages also raises the probability that a worker will be absent by 5%.

But it’s not just about productivity. In healthcare settings like hospitals, thermal comfort can improve patient wellbeing, speeding up and improving their recovery outcomes. It also takes the pressure off healthcare workers, enabling sick and injured people to feel cared for, confident, and at ease without too much staff intervention. Despite this, patients are likely to be wearing far less clothing than staff, and carrying out minimal activity. As such, providing the right level of comfort for everyone can be a real challenge.

For some buildings, like hotels and shopping malls, providing good thermal comfort is central to the customer experience – even if it operates subconsciously. Not providing the right conditions can result in lost revenue and a poor reputation. No one wants to stay in a hotel where they don’t feel truly comfortable.

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How Do You Maintain Thermal Comfort in a Building?

Maintaining occupant comfort relies on controlling the thermal environment of your building. In most cases, this control is down to HVAC systems. Despite their prevalence, many HVAC systems are poorly optimised, with manual scheduling and legacy data failing to provide the functionality required to achieve peak conditions. To overcome this problem, building managers all over the world are turning to innovative AI for help.

At Arloid, we train our AI using Deep Reinforcement Learning using a building-specific model that takes into account intricate and highly accurate data. The model is split into microzones, allowing the AI to control areas of the building according to varying requirements. Going back to hospitals, this allows operating rooms to be controlled in one way, and recovery wards in another. The result? An equilibrium of optimum comfort, proactively controlled and maintained.

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Achieve Better Thermal Comfort with Cutting-Edge AI

If you’re ready to discover the power of AI to improve thermal comfort in your building, get in touch with a member of our team! Arloid is transforming the built environment one HVAC system at a time. Our smart solution offers lower energy usage, reduced utility bills, and better performance – all for zero upfront costs. Let’s optimise your comfort today.

Read next: The Power of Deep Reinforcement Learning to Transform the Built Environment

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