Psychrometry Study of air-water mixtures

Psychrometric ChartRelationships between

temperatureabsolute humidity or humidity ratio W in [grain]=[1 lbm/7,000]

or in [lbmwater/lbmair]

relative humidity RH = ratio of actual water content to maximum

possible moisture content at a given temperature [%]

100% RH = saturated air

HVAC System Comforts

Temperature Air quality: no dust, toxic gases, odors Humidity Radiation Air Flow Noise

HVAC Systems

Heating Ventilation Air Conditioning

Who Defines Requirements?

Occupants and their activity, expectations, health Equipment Season (acclimatization) Economics & Market Offering

Celcius vs. Fahrenheit

Celcius 0°C = freezing of ice 100°C = boiling of water at 1 atm

Fahrenheit 0°F = freezing of seawater 100°F = melting of butter 212°F = boiling of water

t [°C] = (T [°F] – 32°F) * 5/9 °C/°For

T [°F] = 1.8 °F/°C * t [°C] + 32 °F

Temperature

Dry bulb Wet bulb evaporative cooling

[Bradshaw 1993]