Summary of Thermal Comfort

Summary

This chapter has considered the many facets of thermal comfort. It is important that you are aware that the air temperature at the thermostat is not always a good indicator of thermal comfort. The design of the space and individual clothing choices can have major influences on thermal comfort.

Section 3.1 Introduction – What is Thermal Comfort?

Standard 55 defines comfort as “that condition of mind which expresses satisfaction with the thermal environment; it requires subjective evaluation.”

Section 3.2 Seven Factors influencing Comfort

You have personal experience of the seven factors that affect thermal comfort: personal comfort, including activity level and clothing; individual characteristics, including expectation; environmental conditions and architectural effects, including air temperature, radiant temperature, humidity, and air speed.

Section 3.3 Conditions for Comfort

This section focuses on the factors that influence thermal comfort in normal living environments and office-type environments with occupancy periods in excess of 15 minutes. These include occupant operable windows and naturally conditioned spaces, and mechanically conditioned spaces. Mechanically conditioned spaces are arranged into three classes: Class A – high comfort; Class B – normal comfort; Class C – relaxed standard of comfort. The Standard provides a psychrometric chart showing 80% acceptable conditions for a Class B space for activity between 1.0 and 1.3 met; clothing 0.5 to 1.0 clo; air speed below 40 fpm; with the added condition that the person is not in direct sunlight. To calculate comfort conditions for Classes A and C, the designer uses a BASIC computer program.

Section 3.4 Managing Under Less Than Ideal Conditions

Non-ideal conditions include: elevated air speed, draft, vertical temperature difference, floor surface temperatures, cyclic temperature changes, and radiant temperature variation.

Section 3.5 Requirements of Non-Standard Groups

Most of the research for Standard 55 was based on the responses of healthy adults. When designing for non-standard groups, consider their additional needs for comfort.