94. Subjective methods for complex microclimate evaluation.

10 + 11) methods for complex microclimate evaluation – subjective, objective and integral methods

-microclimate: consists of 4 main parts: temperature, air velocity, humidity and IR radiation

-subjective methods and objective methods

-subjective: questionnaire method of subjective thermal sensation (7-bale scale of Bedford), effective temperature index (ET), corrected effected temperature index (CET), fanger’s comfort criteria of thermal comfort

-objective: physical and physiological methods

-thermal comfort interacts with productivity, amount of errors and accidents, health…

• Thermal comfort: condition of mind which expresses satisfaction with the thermal environment (also with light, quality, noise level…) -> could be maintained when heat production of the body is equal to the heat loss of the body

SUBJECTIVE METHODS

1. Questionnaire method of Bedford (7-bale): very hot, hot, warm, comfort, slightly cool, cool, cold (thermal sensation which depends on personal features: age, gender…)
2. Effective temperature (ET) index: can be obtained from air velocity (m/s), dry bulb temperature (°C) and wet bulb temperature (°C) -> effect of temperature, humidity and air movement combined into a single value for sensation of warmth or cold

• Comfort zone: 17,2 – 21,7°C; comfort line: 18,1 – 18,9°C

3. Corrected effective temperature index (CET): is like the ET just that it also takes a heat radiant (if present) into consideration (-> so 4 factors, not 3), substitution of dry bulb temperature for globe temperature
4. Fanger’s comfort criteria for prediction of thermal comfort: 4 physical (relative humidity, air temperature, air velocity, mean radiant temperature) and 2 personal variables (clothing insulation and activity level) => predicted mean vote (PMV); 7-point scale (cold(-3), cool, slightly cool, neutral(0), slightly warm, warm, hot(3))

OBJECTIVE METHODS

-Physical methods

1. Resulting temperature (RT): give information of thermal state of a room (especially with great heat radiation; when surrounding temp is higher than skin temp OR when surrounding temp is lower than air temp) -> thermal comfort sensation form normal dressed man: RT = 17-19°C
2. Wet bulb globe temperature index (WBGTi): similar to RT but takes into account also the work/rest regimen, acclimatization, type of work clothing… (for indoor and outdoor) -> WBGToutdoor = 0,7 tg + 0,1 tdb + 0,2 twb AND WBGTindoor = 0,7 tg + 0,3 twb

• tg = globe thermometer temp.; tdb = temp. of dry bulb; twb = temp. of wet bulb
• also work/rest regimen and thermos resistance clothing should be taken into account

-physiological methods

1. Pulse frequency
2. Dynamics of blood pressure