1. Environmental Controls I/IG Lecture 6 Thermal Comfort

2. Terminology Abbrev.Units Psychrometrics------ Relative Humidity RH(%RH) Dry Bulb Temperature DBT(ºF) Wet Bulb TemperatureWBT(ºF) Dew Point TemperatureDPT(ºF) Standard Comfort Zone------

3. Psychrometrics Measurement of moisturecontent and air temperature.

4. Relative Humidity Quantity of moisture held in the air relative to the maximum amount that can be held (%). Warm air holds more moisture Moisture condenses from the air as it cools

5. Relative Humidity What is 100% RH? Fog

6. Dry Bulb Temperature Air temperature as read from a standard thermometer Dry Bulb Temperature ºF

7. Wet Bulb Temperature Air temperature as read from a moistened thermometer Wet Bulb Temperature

8. Dew Point Temperature ºF Dew Point Temperature Temperature at which RH is 100%

9. Dew Point Temperature For air at 75ºF/65% RH, what is the dew point temperature? Dew Point Temperature ºF 60ºF

10. Standard Comfort Zone Conditions where the typical occupant is comfortable for the given intent of a space. [L: p. 65, fig. 4.8a]

11. Influenced by Metabolism Migration Heat flow Clothing Thermal Comfort Factors

12. Metabolism Metabolism affects perception of thermal comfort Muscular activity Digestive process Daily cycle Health Age Gender

13. Migration Body attempts to maintain core temperature (98.6ºF) by shifting blood flow Vasodilation Vasoconstriction

14. Heat Flow Multiple mechanisms Convection Conduction Radiation Evaporation

15. Heat Flow – Convection Air movement caused by pressure and density changes Wind is formed by air moving from high to low pressure areas Warming air rises Cooling air falls

16. Heat Flow – Conduction Caused by direct contact between two objects of different temperature Heat always flows from warm to cool

17. Heat Flow – Radiation Radiant heat is exchanged by two objects of different temperatures Heat always flows toward cooler object Surface temperature controls interaction Seasonally variable

18. Radiant Heat Flow Season variations can change direction of radiant heat flow

19. Mean Radiant Temperature (MRT) MRT approach is used in Europe as a means to lower operating temperatures

20. Heat Flow – Evaporation Water changes from liquid to gas and this phase change extracts heat Respiration Perspiration

21. Compounds and/or mitigates the effects of other mechanisms Clothing