Thermal confort

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ASHRAE Standard 55 (ASHRAE, 1992)
ISO Standard 7730 (ISO, 1994)

That condition of mind which expresses satisfaction with the termal environment
4 Environmental factors:
_ Air temperature
_Radiant tempertaure
_ Air velocity
_ Humidity
2 Personal factors:
Clothing insulation
Metabolic heat
Some extra factors:
_ Health,
_ psychology
_ sociology

Clothing level estimation: clothingis classified according to its insulation value
(1 Clo = 0.155 m²°C/W)

The metabolismo: The metabolism is the energy released in by oxidation processes in the human body which depends on themuscular activity.
(1MET=58 W/m² of body surface).
A normal adult has a surface of 1.7 m², and a person in thermal comfort with an activity level of 1 Met will thus have a heat loss of approximately100 W.

Mean radiant temperature:
Thermal indoor climate: man does not feel the room temperature, he feels the heat loss from the body.
Parameters that must be measured: Air Temperature, MeanRadiant Temperature, Air
Velocity and Humidity

Influence of humidity on thermal comfort


3.Measurement of thermal conditions

WBGT – Heat Stress Monitor

Heat Stress Monitor takesreadings from, and calculates WGBT by:
- Dry Bulb Thermometer
-Wet Bulb Thermometer
-Globe Temperature

Effective Temperature


C. Wet-Bulb Globe Temperature Formula (WBGT)For indoor or shaded environments:

WBGT = 0.7 x Tnwb + 0.3 x Tg
Tnwb = natural wet-bulb temperature
T = globe temperaturT e g temperature

Fordirect sunlight exposure:
WBGT = 0.7 x Tnwb + 0.2 x Tg + 0.1 x Tdb
Tdb = dry-bulb temperature

ISO 7730 Thermal environment

PMV (Predicted Mean Vote) is thesensation of: +3 hot, +2 warm, +1 slightly warm, 0 neutral, -1 slightly cold, -2 cool, -3 cold.

PPD means Predicted Percentage Dissatisfied with the thermal environment.

DR, Draught is an...
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