Basic Factors that Influence Thermal Comfort

T he thermal environment is one of the main factors related to comfort in any environment. Feeling too hot or cold has immediate repercussions on one’s well-being and comfort, so it’s imperative that you create the conditions your body prefers to feel completely in your element.

A common misconception is that air temperature is the sole factor that influences thermal comfort. However, the truth is as far as it can get. A total of six factors contribute together, four of which are environmental and two personal. So stick with me until the end if you want to learn these six thermal comfort factors and what you can do to control and manage this critical comfort factor. Without further ado, let’s move on to our topic of interest.

The Six Basic Factors of Thermal Comfort

The ASHRAE Standard 55 defines thermal comfort as the condition of mind of an individual that shows satisfaction with the thermal environment. But, of course, since it varies from one individual to another based on personal preferences, it is a subjective form of evaluation.

For you to be able to control and manage thermal comfort, you first need to learn what exactly influences it. There are a total of six factors that are independent of each other but contribute side-by-side to determining thermal comfort. As I mentioned in the introduction part of the article, four are environmental factors, and two are personal factors. So let’s look at each category and learn more about each specific element to give you a better grasp on this topic.

Room Air Temperature Shown on Smartphone Display

The Environmental Factors:

• #1. Air Temperature

  I listed the most apparent factor first since it’s the one influential element you likely suspected from the get-go. Air temperature refers to the temperature of the air surrounding your body. To put it in simpler words, it is the temperature the thermometer indicates in the room or space you sit in.

  If you want to learn how thermal comfort fares when you are outside from this specific point of view, you have to use an indoor-outdoor thermometer that can show you the air temperature values in the external environment. This particular type of thermometer can indicate more comprehensive temperature ranges and works in colder or hotter climates without getting damaged or having its accuracy affected.

  Note: Thermometers show the air temperature in either Celsius or Fahrenheit values. Some models indicate air temperature in both types of readings. If you are keen on a thermometer that only provides readings in one of these measurements instead of both, then opt for a model that shows values in the measurement you are accustomed to.

• #2. Radiant Temperature

  It differs from air temperature because the radiant temperature is the heat that radiates from warm objects. These can include ovens, fires, the sun, hot surfaces, machines, appliances, cookers, electric fires, and more. In short, it is only present when there is a heat source in the environment.

  While air temperature impacts how we feel in a specific environment and how much heat we gain or lose in it, the radiant temperature has a much more significant influence on us than the first thermal factor we discussed. So if you seek a much more potent heating source for balancing thermal comfort, the radiant temperature is the better answer.

• #3. Humidity

  Humidity is an influential factor in indoor air quality, a topic I expand on in this article. And it is just as crucial for thermal comfort. Humidity results when water is heated and evaporates in the environment. Relative humidity, on the other hand, refers to the ratio between the amount of air water vapor and the peak amount of water vapor the air can hold, depending on the temperature.

  With relative humidity, RH for short, studies show that values ranging from 40% to 60% are what we should aim for indoors to protect the building’s construction and our health. There is more to it than this, though. As long as air moisture levels are kept within the parameters above, thermal comfort is not negatively impacted.

  Low humidity isn’t desirable either, but the much greater issue for thermal comfort is posed by relative humidity that exceeds the 60% threshold. In a humid environment, the amount of vapor in the air prevents sweat from evaporating from your skin. However, since sweat evaporation is a primary means of heat reduction, you can see why maintaining proper humidity is a must, especially in summer.

• #4. Air Velocity

  It refers to the speed at which air moves across the individual. Stale air indoors can easily make the environment feel stuffy and uncomfortable. If you are feeling hot, for example, air velocity would help cool you off since the breeze would create that invigorating cooling sensation you seek. This is why fans are so prevalent in offices. They provide a means for air to circulate and make hot people feel comfortable when it comes to thermal conditions, all without reducing the air temperature in the room so that people who prefer warmth won’t be discomforted by their operation.

Woman Dressed in Warm Clothes

The Personal Factors:

• #5. Clothing Insulation

  The amount of insulation provided by clothes is another major influential factor since wearing too many or too few can lead to thermal discomfort. For example, if you wear too many clothes in an already hot environment, you will feel hot, too, and suffer the repercussions of heat stress. On the other hand, if you dress in light layers, you might feel cold and suffer frostbite. Luckily, adapting to conditions from this point of view is easy.

• #6. Metabolic Heat

  Although it is the last factor we discuss, don’t underestimate its role because it is critical for thermal comfort. As you perform physical activities, you start producing more heat. The more our body produces, the more we have to lose to prevent the sensation of overheating. In addition, certain aspects influence metabolic heat greatly, including age, gender, weight, size, and fitness level. These factors majorly affect how warm or cold an individual feels regardless of how much physical activity they do.

Woman Warming Up Near Radiator

How to Control Thermal Comfort

Achieving satisfaction in the thermal environment is quintessential since thermal conditions can be life-threatening under certain circumstances. This happens when the core body temperature reaches hypothermia conditions (when body temperature is below 95 degrees Fahrenheit) or hyperthermia (when body temperature is over the 99.5 to 100.9 degrees Fahrenheit limit).

So the question is, how do you control thermal comfort indoors? Luckily, there are several ways to go about this. Here are a few tactics that you should employ:

• When the air temperature indoors is too low, use heating systems to warm the space up.
• When the air temperature indoors is too high, turn on the air conditioning system to lower the temperature and make it feel cooler.
• Take off clothes if you feel too warm, or put on thicker layers in case you feel cold.
• If you notice condensation or the hygrometer is indicating values exceeding the 60% threshold, turn on a dehumidifier to remove excess moisture from the air.
• If the air feels warm yet dry, you should use an evaporative cooler to solve both issues simultaneously, raising humidity while lowering the temperature.
• Insulate the walls. This will slow heat flow in summer and heat loss in winter, making a significant difference for the better when it comes to thermal comfort. Moreover, proper insulation helps keep the bills low since it makes your home more energy efficient.
• Listen to your body, and don’t strain yourself. If you feel too hot after a particular physical activity, take a break and cool off.
• Turn on a fan when the air feels too stuffy at the office. This way, you cool off without turning on the AC, which is something that not all of your coworkers might feel comfortable with.

The Takeaway

Managing thermal comfort can benefit your morale and productivity, especially at your workplace. But it’s just as important at home or in any other environment. As long as you feel comfortable with the thermal environment that you are in, your body stays at the right core temperature, and there are no potential health repercussions.

Now that you know what the six factors that influence thermal comfort are, it will be a lot easier for you to take control and create proper conditions for you to be in. Remember that thermal comfort differs from one person to another, so when you live with other people, you must find solutions so that everyone feels in their element.