Testing Thermal Comfort - A.D.A.M. - The Right Man for the Job
Copyright (c) 2010, Robert Bean, All rights reserved, originally published in HPAC Canada
(A.D.A.M. = Advanced Automotive Manikin used for thermal comfort research)

Sit down with a group of contractors, distributors or designers to discuss HVAC instrumentation and inevitably it will come around to thermography, blower doors, moisture meters, carbon monoxide testers and combustion analyzers. Surprisingly for an industry based on comfort, rarely if ever does thermal comfort instrumentation become a topic simply because outside of academia nobody knows the tools exists.

Instrumentation to measure thermal comfort has been around in various forms for decades. The types similar to those employed in Canada’s NRC-IRC test house (2004/5) are useful when mounted to robotic systems or in portable systems like those developed by The College of Environmental Design, U of C, Berkeley (1990). Such tools measure radiant asymmetry, operative temperature (average of the mean radiant temperature and dry bulb), air velocity, humidity, and thermal stratification. Sensor feedback coupled with understandings of human physiology including core and skin temperatures and sensible and latent exchanges at various metabolic rates wearing different clothing, allow researchers to make reasonable predictions of thermal satisfaction within the built environment.

Beyond the history of instrument carts or sensor trees is the evolution of thermal manikins which has served researchers for more than 60 years. They are widely used to studying the thermal properties of clothing and in the evaluation of human comfort in occupied spaces like vehicles and offices. Recent developments of sweating manikins and breathing manikins allow more realistic simulations of the human interaction with various environments.

History

During the 1930's, thermal resistance in clothing was tested with flat plates and heated cylinders. In 1939 the first ever thermal manikin was built by General Electric to test an electric blanket leading eventually to the development of the clo unit in 1941 by Gagge, Burton, and Bazett and the early beginnings of instrumented studies of man, clothing and his environments. It was in this period, which Dr. Harwood Belding commissioned (1941/42) the fabrication of a manikin constructed from copper (Built by General Electric). A civilian contractor working for the military at the Harvard Fatigue Laboratory, Belding was testing protective clothing and equipment using human volunteers at the time. As noted by Measurement Technology Northwest, “In September 1945, General Electric was asked to build the next generation thermal manikin for the Climatic Research Laboratory. General Electric combined its previous manikin expertise along with detailed data from an anthropometric study of nearly 3000 Army Air Force cadets to construct another electroplated copper shell manikin with a total of six separate electrical circuits and based on the average physical dimensions of a young U.S. military recruit. “

In the next two decades following WWII, the Aero Medical Research Laboratory at Wright Air Field in Dayton, Ohio, the Climatic Research Laboratory in Lawrence, Massachusetts and ultimately the new U.S. Army Research Institute of Environmental Medicine (also known as "USARIEM") located at Natick, Massachusetts did extensive testing using manikins. In 1964, an aluminum unit was produced in the U.K followed by a French made model in 1972. This unit could be cooled to study heat gains and heat protective clothing. Denmark produced the first plastic version in 1973 followed by Germany in 1978. These units were the first moveable types and the last of the analogue versions. Digital moveable units came out of Sweden between 1980 and 1984. The U.S. then produced a model to be used in intense radiative and convective heat application with Canada working on a water immersion type in 1988. A Scandinavian consortium and a Japanese group both introduced models to study heat exchange by evaporation with sweating manikins in the same decade. Also in 1988, a Finnish product was created as well as the first female plastic manikin developed by the Danes. This product was the forerunner to many of modern thermal comfort manikins used today and later was advanced in 1996 with a breathing simulation feature. The Swiss in 2001 took the sweating types to a new level by introducing a multi zone unit comprising of 30 dry zones and 125 sweat zones. Between 2000 and 2002, the Chinese, British, Swedes and Japanese all worked with virtual computer units with numerical geometric zones for simulation studies in heat and mass transfer. China also built in this period a single segment water heated product for studying sweating. This was followed in 2003 by an American made air heated self contained sweating manikin with 126 zones fabricated of metal and another model constructed of a breathable windproof fabric. Today’s modern manikins like those engineered by Measurement Technology Northwest are completely self-contained carrying a water reservoir for the sweat glands, batteries for segment heating and all the circuitry needed for regulation and data acquisition. Their human shapes measures convective, radiative and conductive heat losses in all directions over the whole surface or a defined, local surface area.

Over the years Manikins have been used to test such well known fabrics as Gore-Tex^(tm), Thinsulate^(tm), and Primaloft^(tm) and have found themselves in research projects testing flight suits, cold water survival suits, combat gear and thermal comfort in automobiles and office environments. Though these comfort tools tend to fall way outside the affordability range to be considered part of the service contractors test instruments, the ones used by NRC or the University of California are becoming more attractive for basic models.