environmental comfort

Question 1

variables that affect comfort in building?

Answer 1

-room temp
- airflow
- humidity
- radiation
- indoor air quality

Question 2

what temps does body feel most comfortable?

Answer 2

• winter: 22.2 - 25.5
• summer: 22.2 - 24.4

Question 3

what is humidity?

Answer 3

• moisture in the air
• high humidity less heat absorbed from body
• low humidity more heat absorbed from body

Question 4

airflow?

Answer 4

• rate of air motion
• increased air flow increases heat evaporation from body keeping it cool

Question 5

radiation?

Answer 5

• heat flows from hot to cold surface
• comfort can be increases by directing warm air towards cold surfaces, why most heating elements are located under windows

Question 6

HVAC designed for?

Answer 6

• thermal conditioning
• adequate count of outdoor air

Question 7

two types of humidity?

Answer 7

• absolute humidity
• relative humidity

Question 8

dry air?

Answer 8

no water vapour

Question 9

moist air?

Answer 9

some water vapour

Question 10

saturated air?

Answer 10

max amount of water vapour

Question 11

how is relative humidity measured?

Answer 11

hydrometer

Question 12

how to dehumidify air?

Answer 12

cool it

Question 13

what is the dew point (DPT)

Answer 13

temp of air/water vapour mixture when fully saturated

Question 14

frost point temp?

Answer 14

when dew point is below freezing creating frost instead of dew

Question 15

condensation?

Answer 15

process of removing liquid from air

Question 16

effect of temp on humidity

Answer 16

• moisture holding capacity
• warm air holds more than cold air

Question 17

dry bulb temp (DBT)

Answer 17

temp of the mixture of air and moisture at rest, measured with thermometer

Question 18

wet-bulb temp?

Answer 18

• by comparing the dry and wet bulb temperatures we can determine the temp and humidity of air

Question 19

specific volume?

Answer 19

ratio of unit volume of air per weight of dry air

Question 20

enthalpy

Answer 20

quantity of heat contained in air under specific conditions

Question 21

psychrometric chart

Answer 21

graphical representation of thermodynamic properties of moist air

Question 22

what is relative humidity

Answer 22

ratio of actual water to max amount of water at the same temp and pressure

Question 23

what two ways does air contain thermal energy

Answer 23

• temperature
• water vapour

Question 24

sensible heat?

Answer 24

heat is associated with temp change

Question 25

temperature is a measurement of what

Answer 25

sensible heat

Question 26

what are all the material states

Answer 26

- solid - liquid -gas

Question 27

latent heat?

Answer 27

release or storage of heat associated with change in phase of substance

Question 28

water vapour is measurement of what?

Answer 28

also latent heat

Question 29

heating cooling is change of what

Answer 29

change od sensible heat

Question 30

humidification and dehumidification is change of what

Answer 30

is a change of latent heat

Question 31

sensible heating (cooling)

Answer 31

when temp of air water mixture is raised, but moisture remains the same

Question 32

cooling and dehumidification

Answer 32

lowering temp and humidity ratio

Question 33

evaporating cooling

Answer 33

sensible heat converts to latent heat in the added vapour

Question 34

heating and humidification

Question 35

desiccant dehumidification

Answer 35

chemical or physical absorption of water vapour to dehumidify air

Question 36

what fluids does the HVAC system carry to transport heat and cold

Answer 36

- air - water - steam - refrigereant

Question 37

what is heat measured in

Answer 37

british thermal units (BTU)

Question 38

what is 1 btu

Answer 38

the heat to raise 1lb of water 1F

Question 39

heating loads?

Answer 39

how much heat is lost and must be made up

Question 40

cooling loads?

Answer 40

how much heat must be removed

Question 41

what is critical condition design

Answer 41

- outside weather - solar effects - inside temp - humidity - status of building operations

Question 42

critical deasign for heating occurs when

Answer 42

with super cold weather

Question 43

critical design for cooling is when

Answer 43

with super hot conditions

Question 44

what does the amount of ventillation depend on?

Answer 44

- type of occupancy - number of occupants