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MS Topic 5 Thermal Comfort - Coggle Diagram
MS Topic 5 Thermal Comfort
Introduction
Body loses heat through - radiation, convection, evaporation and conduction
Radiation (Aircon)
Temperature will noticeable increase in non-airconditioned room with more people
Airconditioner helps to lower room temperature and body to lose heat
Skin Temperature is higher than environment, body lose heat through radiation
Factors Affecting Thermal Comfort
Personal Factors
Office work - 140w
Factory assembly work - 265w
Sleeping - 70w
Heavy lifting work - 440w
Clothing - act as thermal insulator to maintain at comfort thermal level
Environmental Factors
Relative humidity - humidity caused by moisture in the air
High RH - Moist air and feel oppressive
Air temperature
Low RH - Dry air and skin feel dryness
High RH slows down evaporation, ones will feel humid and uncomfortable as sweat remains on skin
Air movement - Increases heat loss through convection
Surface Temperature - Radiation, air condition
criterial for Ideal Thermal comfort
Room temperature kept at 24 to 26 degree - Radiation
Relative Humidity 50% -70% - Lose heat through evaporation
Minimum 1.0 air change per hour
Air movement not exceed 0.2ms/s or below 0.05m/s - Create air circulation of enclosed area to reduce stuffiness
Convection (Fan)
Fan/ natural wind cool off body - Convection
Amount of heat loss depends on airflow over the skin
Process of losing heat through movement of air across skin
Conduction (Metal chair)
Process of losing heat through contacting object
For example, sit on metal chair body will lose heat to the cold metal chair
Evaporation (Sweat)
When clothing gets wet from sweating, liquid evaporate and result in cooling effect
Subjective Characteristic of Thermal Comfort
Short duration of extreme condition may not cause discomfort
Individual might not feel discomfort under hot sun on beaches, but may feel discomfort on street with same condition
Woman, elderly and young children require higher air temperature
Effect of Solar Radiation
Orientation of building - West facing windows will receive more solar radiation
Season of the year - cooler weather on dec-Jan
Geographical latitude of site - Countries near equator will receive high level of solar radiation and experience frequency thunderstorm
Local cloud condition - More cloud coverage reduce level of solar radiation
Types of window glass - tinted or clear glass
Material of roof and external walls - Material that are better conductors will attract more radiation
Selection of material can determine amount of solar radiation. Some are better conductor while some are better insulators
Larger window allow more lights to transmit into building hence increase temperature - Use of tinted glass or solar film glass can reduce heat