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2.1 T
O
HE
PERATING
By microclimate is meant those environmental parameters that influence the heat exchange between
the person and the surrounding spaces, and that determinate the so-called " thermal well-being".
The microenvironment climatic factors, together with the type of work performed, generate a series
of biological responses linked to thermal well-being (Comfort) or uneasiness (Discomfort).
The human organism, indeed, tends to maintain a thermal balance so that the body temperature is
optimum.
The HD32.1, Thermal Microclimate, through its operating program A: Microclimate Analysis
measures the following quantities:
• t
: natural ventilation wet bulb temperature
nw
• t
:
globe thermometer temperature
g
• t
:
environment temperature
a
• p
:
atmospheric pressure
r
• RH: relative humidity
• v
:
wind speed
a
In addition to the direct measurements performed with the probes connected, the instrument can
directly calculate and display the following well-being data:
• WBGT index
• Tu index
• WCI index
• Average radiation temperature t
2.1.1 WBGT Index
WBGT (Wet Bulb Globe Temperature) is one of the indexes used to determine the thermal stress of
a person in a hot environment. It represents the value, related to the metabolic output linked to a
specific work activity, that causes a thermal stress when exceeded. The WBGT index combines the
measurements of the natural ventilation wet bulb temperature t
temperature t
and, in some situations, with the air temperature t
g
following:
• Inside and outside buildings without solar radiation:
• Outside buildings with solar radiation:
where:
t
= natural ventilation wet bulb temperature;
nw
t
= globe thermometer temperature;
g
t
= air temperature.
a
The measured data should be confronted with the limit values prescribed by regulations; when
exceeded you have to:
HD32.1
2. WORKING PRINCIPLE
P
A: MICROCLIMATE ANALYSIS
ROGRAM
r
WBG
enclosed spaces
WBGT
outdoor spaces
= 0.7 t
+ 0.3 t
nw
g
= 0.7 t
+ 0.2 t
+ 0.1 t
nw
g
- 8 -
with the globe thermometer
nw
. The calculation formula is the
a
a
V2.1
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