Lecture 3 - Thermal Comfort

Question 1

What are the Physical variables of thermal comfort?

Answer 1

• air temperature
• mean radiant temperature
• air velocity
• humidity

Question 2

What are the Personal variables of thermal comfort?

Answer 2

• activity (metabolic rate)
• clothing
• age
• gender

Question 3

Explain the Mean Radiant Temperature

Answer 3

The temperature of the surrounding SURFACES can affect thermal comfort as much as the temperature of the air.

The MRT should be kept as close as possible to the air temp, but not more than 3 degrees below it.

Question 4

What are 4 examples of causes of thermal discomfort?

Answer 4

1. Local convective cooling of body caused by draughts
2. Cooling/heating of parts of the body caused by radiation (radiation asymmetry)
3. Cold feet and warm head at the same time (vertical air temp difference)
4. Hot or cold feet caused by uncomfortable floor temperature

Question 5

What are acceptable thermal conditions in occupant-controlled naturally conditioned spaces?

Answer 5

1. No mechanical heating/cooling systems installed
2. Occupants with metabolic rates between 1-1.3 met
3. Occupants free to adapt clothing within a range of 0.5 clo
4. Mean outdoor temp between 10-35 degrees

Question 6

What are the comfortable temperature ranges for summer and winter?

Answer 6

Summer: 24-26 degrees
Winter: 18-20 degrees

Question 7

What is the recommended thermal resistance of floors, walls, windows, and roof in Zone 1 & 2?

Answer 7

Floors: 1.3
Walls: 1.9
Windows: 0.26
Roof: 2.9

Question 8

What is the recommended thermal resistance of floors, walls, windows, and roof in Zone 3?

Answer 8

Floors: 1.3
Walls: 2.0
Windows: 0.26
Roof: 3.3