THE THERMAL ENVIRONMENT

THE THERMAL ENVIRONMENT

Just thought I'd create a post about what I've been learning regarding the architectural side of things during my day release to college...

Basically, thermal comfort is defined as "the condition of mind which expresses satisfaction with the thermal environment and is assessed by subjective evaluation" (ASHRAE STANDARD, 55-2004)

There are three broad categories for the thermal environment:

Thermal Comfort

Thermal Discomfort

Thermal Stress

Thermal Comfort refers to where there is broad satisfaction with the thermal environment. This means that most people are neither too hot or too cold - there is an absence of discomfort.

Thermal Discomfort refers to when people start to feel uncomfortable. They are too hot or too cold, but not made unwell - they do not suffer medical symptoms beyond irritability, chills or shivering.

Thermal Stress occurs when the thermal environment causes clearly defined potentially harmful medical conditions such as dehydration or heat exhaustion if it is too hot, or frost bite if it is too cold. Respiratory problems may occur. There is also a risk of hypothermia - a fall or rise in body core temperature can be harmful and potentially fatal. In a working environment, thermal stress can lead to Sick Building Syndrome.

There are six basic factors which can affect thermal comfort. The first four of these are referred to as environmental factors; air temperature, mean radiant temperate, air velocity/speed and relative humidity. The final two factors are more personal; clothing insulation and metabolic heat.

Metabolic heat can relate to age, gender or activity level; some studies show that women actually feel the cold more than men. Drafts on the ankles or back of the neck can instantly make you feel cooler.

Cold Stress/Thermal Shock can also be experienced. This occurs when there is a quick change in temperature which your body is unable to adjust to immediately. An example of this could be if you are on holiday in a hot location and walk into an air-conditioned hotel; the change in temperature is quick and sudden.

The thermal environment is extremely important, and can have an impact on both health and safety; people who are working in uncomfortably hot or cold environments are more likely to behave unsafely because their ability to make decisions and/or perform manual tasks deteriorates. People employ adaptive strategies to cope with their thermal environment; people may take shortcuts as they want to spend less time in the uncomfortable environment, they may not wear PPE correctly or their ability to concentrate on a given task may start to drop off, thereby increasing the risk of errors occurring.