air temperaturerelative humidityair movement surface temperatures air quality (iaq) lighting quality...
TRANSCRIPT
Air temperature Relative humidity Air movement
Surface temperatures
Air quality (IAQ)
Lighting
•quality
•quantity
Acoustics
Security
Building Envelop -The Third Skin
The 3rd. skin moderates the differences between the
natural environment and the built environment
75 degrees
65 degrees
+100
- 5
The combined affects of environmental conditions on comfort
•Air temperature
•Relative humidity
•Air movement
•Surface radiation
Dry Bulb Temperature Reading
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The psychrometric chartCharts the combined affects of air temperature and moisture content
50% RH
Psychrometric ChartDefinition of Relative Humidity
The amount of moisture in the air expressed as a percentage of the maximum amount of moisture the air can hold at the given temperature.
Example: at dry bulb temp. of 77 and wet bulb temp. of 63, the air is holding 50% of it’s maximum capacity at 77 degrees.
Enter dry bulb reading
Enter wet bulb reading
warmingcooling
drying
Adding moisture
warmingcooling
drying
Adding moisture
Warm & Dry
Cool & Humid
Winter
Summer
Energy efficient zonesWinter: higher humidity off-sets lower furnace thermostat setting
Summer: lower humidity off-sets higher AC thermostat setting
50% RH
Air is 100% saturated with moisture and condensation begins
The saturation curve
50% RH
Air is 100% saturated with moisture and continues to cool
Moisture removed by condensation
What if cooling continues ?
50% RH
Air is 100% saturated with moisture and continues to cool
Moisture removed by condensation
Same air is reheated to 70 degrees and no moisture added – RH of the room goes down (dryer)
Dry Bulb Temperature Reading
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Chart ExercisesWhat is the RH in the classroom?
Dry bulb ________
Wet bulb _________
RH = _________
Dry Bulb Temperature Reading
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Chart ExercisesBased on the current room RH, how cool would the walls need to get to start noticing condensation ?
Dry bulb ________
Wet bulb _________
RH = _________
Chart ExercisesAssume the room is at pt. “A” when class begin and we are comfortable, which direction would room condition tend to move toward as a response to our presents ?
Mechanically: (Summer)
we need to (add or remove heat)
we need to (add or remove moisture)
A - Room starts out here
B
C
D
E