AE 211 Quiz 1 Flashcards
IEQ
Indoor Environmental Air Quality, the impact of indoor environment parameters on building occupants, subjectively evaluated, aim for 80% satisfaction
Four components of indoor environmental air quality:
thermal environment
air quality
light
sound
Heat balance
metabolism work convection radiation evaporation respiration storage Equation: Metabolic rate – Work = Convective Heat Gain + Radiative Heat Gain + Evaporative Loss + Respiration sensible/latent heat + Storage of energy
Net Heat Gain Responses
YOU ARE HOT
sweating, vasodilation (veins closer to skin surface)
Net Heat Loss Responses
YOU ARE COLD
piloerection, shivering, vasoconstriction (veins farther from skin surface)
TDB
dry bulb temperature, normal F or C temperature, controls convective heat temperature
RH
Relative Humidity, At any given atmospheric pressure and air temperature, there is a maximum amount of moisture a unit of air can hold, this is a percentage of that, sweat can’t evaporate at 100% RH, Sling psychrometer measures at lower than TDB, TDB-TWB on a pressure chart reads RH
MRT
KELVIN, average of all radiant surfaces, measured by globe thermometer and then adjusted for convection, equals the fourth root of (TG^4)+(.247*10^9)(V^.5)(TG-TDB), all temps in Kelvin and V for air speed
TOP
Operative Temperature, average of MRT and dry bulb temperature, involves both convective and radiative heat transfer
Air Speed
high velocity improves heat transfer (feel cooler)
Metabolic rate
Rate at which body consumes energy, depends on activity level, measured in mets, 1 met=58.1W/m^2
DuBois Surface Area
how much skin you have, function of kg weight and m height, =.202(m^.425)(L^.725)
Clo
clothing, insulation value, summer usually .5, winter usually 1
PMV-PPD Heat Balance Method
goal is thermal neutrality, universal applicability
chart is a version of the psychrometric chart
Adaptive Comfort Method
comfort is combination of heat balance, behaviors, and psychological expectations
justifies wider temp range in passive buildings
comfort range varies with “prevailing” outdoor temperature
Thermal Response Scale
-3 (cold or very dissatisfied) to 0 to 3 (hot or very satisfied), satisfied is considered between -1.5 and 1.5 on temperature scale or 0 or above on satisfaction scale
PMV
Average response to an environment of a large group of people using the ASHRAE thermal sensation scale
PMV
Average response to an environment of a large group of people using the ASHRAE thermal sensation scale
IAQ
indoor air quality, gases, particles, microorganisms, part of indoor environmental quality
PMV Comfort Chart
x axis is operative temperature, y axis is humidity ratio, curved lines are wet bulb temperature (RH), version of psychometric chart
Draft effect
within certain ratios can cool people down, but can also reduce thermal comfort, should be less than 1.2m/s
Acceptability
usually minimum of 80% satisfaction
Where does Adaptive model apply?
Building has no mechanical cooling system and heating system is not operating
1.0 – 1.3 met activity level
Prevailing outdoor temperature between 10 and 33.5 degC
0.3 m/s default air velocity
Occupants can adapt clothing level at least within 0.5 – 1.0 clo
Occupants can adjust behavior
Prevailing mean outdoor temperature
average outdoor temperature in a particular location over 7-30 days
80% acceptability limits specified between 14.3 and 21.3 degC above 0.31 times the prevailing temperature
Humidity not considered
Adaptive Comfort Chart
more linear, with prevailing mean outdoor temperature on x axis and indoor operative temperature on y axis
Secondary Factors Affecting Comfort
Day-to-day variations Age Adaptation Sex Seasonal and circadian cycles
