1. Psychrometry
Study of air-water mixtures

2. Psychrometric Chart Relationships between temperature
absolute 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

3. HVAC System Comforts Temperature
Air quality: no dust, toxic gases, odors
Humidity
Radiation
Air Flow
Noise

4. HVAC Systems
Heating
Ventilation
Air Conditioning

5. Who Defines Requirements?
Occupants and their activity, expectations, health
Equipment
Season (acclimatization)
Economics & Market Offering

6. Celcius vs. Fahrenheit Celcius Fahrenheit
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/°F or
T [°F] = 1.8 °F/°C * t [°C] + 32 °F

7. Temperature
Dry bulb
Wet bulb 
evaporative cooling
[Bradshaw 1993]