Presentation is loading. Please wait.

Presentation is loading. Please wait.

Environmental Controls

Similar presentations


Presentation on theme: "Environmental Controls"— Presentation transcript:

1 Environmental Controls
Lecture 6 Thermal Comfort

2 Terminology Abbrev. Units Psychrometrics --- ---
Relative Humidity RH (%RH) Dry Bulb Temperature DBT (ºF) Wet Bulb Temperature WBT (ºF) Dew Point Temperature DPT (ºF) Standard Comfort Zone Mesa Verde: vernacular, passive solar, sun angles, thermal mass

3 Psychrometrics Measurement of moisture content and air temperature.
BH061

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 Relative Humidity

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 Temperature at which RH is 100%
Dew Point Temperature ºF

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

10 Standard Comfort Zone Conditions where the typical occupant
[L: p. 72, fig. 4.8a] Conditions where the typical occupant is comfortable for the given intent of a space. BH048

11 Thermal Comfort Factors
Influenced by Metabolism Migration Heat flow Clothing BH040

12 Metabolism Metabolism affects perception of thermal comfort
Muscular activity Digestive process Daily cycle Health Age Gender BH024

13 Migration Body attempts to maintain core temperature (98.6ºF) by shifting blood flow Vasodilation Vasoconstriction BH024

14 Heat Flow Multiple mechanisms Convection Conduction Radiation
Evaporation BH030

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 BH030

16 Heat Flow – Conduction Caused by direct contact between two objects of different temperature Heat always flows from warm to cool BH030

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 BH030

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 BH030

21 Clothing Compounds and/or mitigates the effects of other mechanisms
BH049


Download ppt "Environmental Controls"

Similar presentations


Ads by Google