Hvac Thermal Comfort

What's the number one customer complaint about their facility? "The office is too cold." What's a close number 2?

"The office is too hot." If you outsource your system and H/C (hot-cold) calls, or are the service provider for them, it

is important to understand the issues behind these complaints. FMs and suppliers know that H/C calls cannot be

handled quickly and uniformly with one technical solution. Solving H/C calls requires an in-depth understanding of

technical HVAC systems, of the factors contributing to human thermal comfort, and of the unique physiological

needs of building occupants.

Indoor thermal comfort is dictated by the building and its occupants. The building has specific design criteria and

limitations based on outdoor conditions, space usage and system capabilities. Occupant comfort is influenced by the

tasks performed, metabolism, age and other personal and physiological factors. Occupants expect the building's

HVAC system to provide continuous thermal comfort, allowing them to do their jobs. Between the building and

the occupants, a facility manager must continually strive to provide thermal comfort in a seamless, invisible manner

to let workers be productive and uninterrupted by thermal discomfort. There are two main sides to thermal comfort the technical (1) and the practical (2) side.

THE TECHNICAL SIDE

The technical standard for thermal comfort comes from ASHRAE (American Society of Heating, Refrigeration and

Air-conditioning Engineers). According to ASHRAE the acceptable operative temperature range from 68 to 74

degrees in the winter and 73 to 79 degrees in the summer. Other considerations are how metabolic rates and clothing

impact thermal comfort. ASHRAE considers a number of mechanical equipment operating conditions to impact a

thermal environment.

THE PRACTICAL SIDE

While the technical side provides an insight into the system requirements and human needs for thermal comfort, in

the practical daily operation of...