THERMAL COMFORT Introduction
Humans seek and want thermal comfort, even at work in industrial settings. Clothing, activities, posture, location, and shelter are chosen, adjusted, altered, and sought consciously and unconsciously to reduce discomforts and enable us to focus more on the other tasks of life. Discomfort can contribute to mistakes, productivity decreases, and industrial accidents.1-^ Thermal discomfort results from the physiological strain of thermoregulation. The strain can be in the form of altered body temperatures, sweating and excessive skin moisture, muscle tension and stiffness, shivering, and loss of dexterity. A small
Amount of discomfort can sometimes enhance concentration and productivity by heightening arousal but too much discomfort is clearly detrimental.
Thus, thermal comfort is clearly desirable and important to the well-being and productivity, and thereby the financial health, of industry. An understanding of the principles of thermal comfort and discomfort can help guide a designer’s efforts in creating and operating industrial environments that are both energy-efficient and thermally acceptable to the occupants.
A commonly expressed definition5 is: “Thermal Comfort is that condition of mind that expresses satisfaction with the thermal environment.” The definition implies that the judgment of comfort is a mental process that results from physical, physiological, and psychological factors and processes. Dissatisfaction can lead to complaints and other undesirable side effects.
Manufacturing engineers, operators, and owners, of course, want to mini mize complaints. A goal in the design process should be to recognize this objective and work to minimize discomfort from the outset. In general, designs that provide satisfying or acceptable environments will be financially more successful for the designer. That is, individual productivity will not be impaired by the environment, resulting in fewer accidents and lost time, fewer complaints, reduced employee turnover, and lower insurance costs.
Why Is One Comfortable? What Affects Our Comfort?
Both primary factors and lesser secondary factors affect our sense of satisfaction with the thermal environment. The primary factors have significant reproducible effects and directly affect heat transfer and the occupant’s thermal state. Secondary factors that may affect one’s sense of satisfaction with a space are conditions such as color and ambiance, local climate, age, physical fitness, sound, food, and illness. These secondary factors have smaller to negligible effects on one’s thermal state and will not be discussed here, but such information is available.6
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