If someone is thermally comfortable within a building, it means they are feeling neither too hot nor too cold. This is important for one's physiological and mental well-being and also promotes productivity, particularly in office environments.
Thermal comfort can only be achieved when the temperature, humidity and air movement within the internal environment are controlled.
The controlled range i.e. the temperatures falling between a set minimum and maximum, is often referred to as the "comfort zone", and establishing this comfort zone involves understanding and combating heat losses and heat gains between internal environments and external environments. Noise and lighting are also considered within the parent issue of human comfort, but not under the more specific heading of thermal comfort.
If we begin with temperature, the level of satisfactory heat will differ amongst individuals for a number of reasons, including activity, diet, genetic make-up, physical build and clothing. The table below helps illustrate this for activity.
Activity
Site Navigation:
Click4Bathrooms
Copyright © 2006 www.click4bathrooms.com
Section:
Thermal Comfort
Created:
20 Oct 07
Updated:
23 Oct 07
This table is from the CIBSE guide – a recognised compilation of data, formulae and principles used throughout the building services and construction industry. The table shows heat emissions dependent on activity for a typical human male. The more heat they are generating, the warmer they will feel. This illustrates how, for example, a sitting office clerk may feel colder than another office clerk that is clearing out bookshelves.
Diet
Diet also affects our body temperatures. Eating foods low in energy or eating nothing at all leads to lower values of heat emission. The break down of food is an exothermic reaction i.e. it produces heat energy as well as energy that can be used in the cells of the body for sustenance. Skipping breakfast in the winter will make you feel colder than if you had eaten something.
Genetics
Regardless of what we actually do or what we consume, some people have higher metabolisms than others and generate more heat. They generally feel warmer in a given environment than people with slower metabolisms. This is an almost impossible factor to control in isolation. Other factors/variables of thermal comfort must be controlled to control this one in turn.
Aside from metabolism, some people are simply more sensitive to temperature change. This is an issue with the central nervous system and is again impossible to control in isolation. Still on the note of genetic make-up, some people have disabilities and internal abnormalities leading to increased or decreased temperatures and temperature sensitivity. Again, this is impossible to control in isolation.
Physical build
A person’s physical build is usually due to lifestyle and long term diet and exercise patterns. Those who are carrying a few extra pounds of fat are more insulated and as a result generally feel warmer than slimmer, less-insulated individuals. This is simply a law of physics and biology. Marine animals such as whales and seals are able to withstand huge pressures and extremes of temperature by deliberately storing up fatty tissues, referred to as blubber. We can also see where many of modern-day insults thrown at overweight people come from in this context.
Clothing
We humans are adaptive animals. We have conquered a vast range of environments by using clothing. Clothing traps heat generated by the human body and is the human form of insulation.
Two people performing the exact same task may both feel uncomfortable. Take two individuals running in a sports hall. One is wearing swimming trunks and one is wearing an arctic jacket. One would feel too cold and the other would feel too hot. This would be a combination of activity and clothing, but clothing is the variable in the example, not activity (they are both running).
Click here for a more in depth look at thermal comfort from a building services engineer's viewpoint.
