ASHRAE Journal - April 2020 - 6

INDUSTRY NEWS

PRINCETON, N.J.-Standard comfort

measurements used to design
buildings' heating and cooling
systems share a common flaw, says
new research published in Scientific
Reports, a Springer Nature Journal.
Princeton researchers said this
could mean designers have relied
on inaccurate measurements for decades when building their systems.
A globe thermometer and associated formulas that calculate comfort
based on the sensor's readings do
not properly account for free convection, according to the research.
This failure led to temperature
errors of more than 2°C (3.6°F) in
experiments.
In thermal comfort research,
globe thermometers have becoming the de facto tool for mean radiant temperature measurement.
The tools are a quick means to
survey a space's radiant environment with nearly a century of
trials to reassure researchers, says
the research. But, as built envi-

ronments become more complex,
the industry needs to reassess the
tool's accuracy.
"Mean radiant temperature is
an established, recognized and
researched metric in the thermal
comfort field and has a large impact
on occupants' perception of the
thermal comfort in a space," said
researcher Eric Teitelbaum, Student
Member ASHRAE. "And while the interaction between the human body
and its surroundings via thermal
radiation is very well understood,
we have demonstrated the basis for
a systematic mechanism that could
under-represent the importance of
radiation relative to air conditions,
such as temperature, humidity and
speed."
Teitelbaum said the researchers do
not make definitive claims, but the
study could help explain why there
are existing studies with simulations
that are far from the measured air
temperature and surface temperature measurements.

Using Virtual Tech to Study
Thermal Effects on Occupants

BATON ROUGE, LA.-To analyze how humans and buildings interact during the building design phase, a
Louisiana State University research team is using
immersive virtual environments (IVEs) to measure
people's sensation and comfort due to changes in
temperature, humidity and airflow. Sensors measure the participants' physiological responses as the
experimental facility's environment changes.
LSU Construction Management Professor Yimin

ASHRAE JOURNAL

ashrae.org

APRI L 2020

Eric Teitelbaum

Study: Measurements Flaw Could Lead
To Heating, Cooling Design Errors

Researchers found millions of mean radiant temperature
measurements made using globe thermometers could
be systematically flawed, affecting thermal comfort research, building controls and modeling.

"We hope that engineers will read
this study and rethink the potential
impact of mischaracterized radiant environments in their work," he
said.
Teitelbaum said the research
team is now conducting a precise
validation of its methods in a
highly controlled climate chamber.
To read the study, visit http://tiny.
cc/thermalcomfort.

Zhu, the research team's leader, said researchers have
said not being able to observe human-building interactions contributes to buildings' performance gaps.
"While the (IVE) technology is increasingly being
used in design and engineering, such as in design
validation, the potential of using it for understanding
thermally driven behaviors is not known," said Zhu.
"This is because the technology itself cannot effectively provide thermal stimuli."
By integrating IVE with an external heating/cooling source, the researchers hope to develop a reliable
experiment and data collection method for designers.

http://tiny.cc/thermalcomfort http://tiny.cc/thermalcomfort https://www.ashrae.org

ASHRAE Journal - April 2020

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