Air temperatureRelative humidityAir movement Surface temperatures Air quality (IAQ) Lighting quality quantity Acoustics Security Building Envelop -The Third Skin The 3 rd. 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 Change in quantity of water in the air The psychrometric chart Charts the combined affects of air temperature and moisture content
50% RH Psychrometric Chart Definition 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
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 Change in quantity of water in the air Chart Exercises What is the RH in the classroom? Dry bulb ________ Wet bulb _________ RH = _________
Dry Bulb Temperature Reading Change in quantity of water in the air Chart Exercises Based on the current room RH, how cool would the walls need to get to start noticing condensation ? Dry bulb ________ Wet bulb _________ RH = _________
Chart Exercises Assume 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
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