HD32.3TC
- 9 -
V1.1
•
Energetic waste = 1 ÷ 4 met
•
Clothing thermal impedance = 0 ÷ 2 clo
•
Wet bulb temperature = 10 ÷ 30 °C
•
Mean radiant temperature = 10 ÷ 40 °C
•
Air speed = 0 ÷ 1 m/s
•
Vapour pressure = 0 ÷ 2.7 kPa
The PMV index is therefore an index particularly suitable for the evaluation of
working envi-
ronments with moderate microclimate
, such as houses, schools, offices, laboratories, hos-
pitals, etc.; it is useful in detecting limited degrees of thermal discomfort in residents of such
environments.
ISO 7730 standard suggests PMV values b0.5 and -0.5 for the thermal comfort, which
corresponds to a percentage of dissatisfied with the thermal conditions (PPD) less than 10% (see
the following table).
Table 3.2
: thermal sensation scale
PMV
PPD (%)
THERMAL SENSATION
+3
100
Very Hot
+2
75.7
Hot
+1
26.4
A little bit warm
+0.85
20
Acceptable thermal environment
-0.5…+0.5
< 10
Thermal well-being
-0.85
20
Acceptable thermal environment
-1
26.8
A little bit cold
-2
76.4
Cold
-3
100
Very Cold
For the calculation of PMV and PPD indices it is necessary to know:
•
The working charge (energetic waste);
•
The thermal impedance of clothing.
The working charge
can be quantified using the following units of measurement:
•
kcal/h (1 kcal/h = 1.163 W):
with this unit it is expressed the average power per hour
supplied by an individual during the working activity;
•
MET (1 MET = 58.15 W/m
2
):
with this unit it is expressed the total power per hour
supplied by an individual during the working activity divided by the body surface of the
individual.
Clothing thermal impedance:
The clothing thermal impedance is measured in CLO.
1 CLO = thermal gradient of 0.18 °C on a 1 m
2
area crossed by 1 kcal/h thermal flow.
The following tables can help to establish the thermal impedance values of the clothing and the
working charge (metabolism).
Summary of Contents for Delta OHM HD32.3TCA
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