Humid Air
Water vapor in air
Oxygen 21%
Trace Glasses 1%
Argon (A)
Water vapor (H2O)
Carbon dioxide (CO2)
Neon (Ne)
Helium (He)
Krypton (Kr)
Hydrogen (H)
Ozone (O3)
Nitrogen
78%
Image by MIT OCW.
Humid Air
Water vapor in air
ƒ
ƒ
ƒ
ƒ
ƒ
saturation humidity (SH) (= max AH)
moisture content (absolute humidity AH) = kgvapor / kgdry air
(partial) vapor pressure [Pa]
relative humidity (RH)
GAZE
wet-and-dry bulb psychrometer
ETHER
Image by MIT OCW.
Humid Air
Water vapor in air
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
saturation humidity (SH) (= max AH)
moisture content (absolute humidity AH) = kgvapor / kgdry air
(partial) vapor pressure [Pa]
relative humidity (RH) in [%]
wet-and-dry bulb psychrometer
enthalpy (H) in [kJ/kg]
­ Sensible heat vs. Latent heat
ƒ specific volume
Humid Air
Psychrometric chart
absolute humidity AH and saturation line
relative humidity RH
wet bulb temperature
enthalpy
specific volume
e
lin
n
tio
tu
ra
16
12
4
0
10
20
40
30
0
bu
l
b
te
g)
J/k
(k
m
pe
ra
tu
re
(
C)
30
80
10
20
30
40
75
0
50
50
00
30
20
40
Dry bulb temperature ( oC)
25
60
50
0.8
70
25
90
0.8
10
0.9
100
P
00
W
et
110
0.8
10
20
60
120
0.9
40
15
50
130
0.8
10
20
70
130
50
0.93 /kg)
(m
25
120
110
100
90
80
0
0
50
0%
10 %
80
%
60
40%
20%
Dry bulb temperature ( o C)
o
5
20
8
30
0
24
Absolute humidity (g/kg)
28
Sa
ƒ
ƒ
ƒ
ƒ
ƒ
(kJ/kg)
Image by MIT OCW.
Humid Air
50
of
nd
ou
35
.018
.016
More Latent
No Change Heat
in Total
Heat
25
Less Sensible
Heat
20
15
.014
More Sensible
Heat
%
20
45
50
55
60
65
70
75
80
o
Temperature F
85
90
95
.010
.006
.004
0%
40
.012
.008
No Change
in Total
Heat
Less Latent
Heat
35
.020
100
105 110
.002
Pounds of Moisture Per Pound of Dry Air
40
%
.022
Absolute Humidity (Humidity Ratio)
10
0%
60
%
ir
.024
Dr
yA
.026
40
30
De
.028
Pe
rP
U
BT
To
t
al
He
at
(
En
th
alp
y)
45
Cooling P Heating
on
ati
c
i
if
id
m
u
h
P
Dew Point Temperature
Temperature Increase (Vapor to Liquid) or Decrease (Liquid
Humidity Increase
Relative Humidity
Dew Point
Amount of condensation
heating and cooling
dew-point then condensation
(de)humidification (adiabatic)
enthalpy increase
Moisture removed by sorbent or
added by evaporation
ƒ
ƒ
ƒ
ƒ
Latent Heat Content Increase
Psychrometric processes
Vapor)
Image by MIT OCW.
Feeling comfortable
Bruits
Noise
Couleur
Color
Eclairage
Lighting
Pureté
l'air
Airde
purity
Humidité
de l'air
Air humidity
Rayonnement
solaire
Solar radiation
Drafts
Courants
d'air
mpérature
des surfaces
Surfaces temperature
Température
de l'air
Air temperature
0
1
2
3
Factors of thermal comfort
Air temperature (sensitive to ΔT > 1°C)
180
160
Heat flux (W)
140
120
100
80
Radiation
60
Conduction
40
Convection
Evaporation
20
0
10
12
14
16
18
20
22
24
26
28
30
32
34
36
o
Temperature ( C)
Image by MIT OCW.
Factors of thermal comfort
Air temperature
ΔT between air and building surfaces (MRT) (keep < 3°C)
Direct Sunlight
Thermal Discomfort
Radiant Energy
Exchange
Direct
Sunlight Glare
Cold Drafts
Image by MIT OCW.
Factors of thermal comfort
Air temperature
ΔT between air and building surfaces (MRT)
Air movement (keep < 1.5 m/s unless overheated)
Image by MIT OCW.
Factors of thermal comfort
Air temperature
ΔT between air and building surfaces (MRT)
Air movement
Relative humidity
(30% to 65%)
Comfort zone
Standard Effective Temperature (SET)
ƒ SET isotherms on psychrometric chart
ƒ neutral temperature Tn = 17.6 + 0.31 x Tmonth (±2.5°C for comfort)
10
0%
85
AH
80
30
25
75
70
35
40
DBT ( o C) 5
45
50
55
60
15
HOT AND
HUMID
65
COLD AND
HUMID
COLD AND
DRY
10
20
20
15
10
COMFORT
ZONE
HOT AND
DRY
5
DRY
25
30
35
40
45
50
Image by MIT OCW.
Comfort zone
Standard Effective Temperature (SET)
ƒ SET isotherms on psychrometric chart
ƒ neutral temperature Tn = 17.6 + 0.31 x Tmonth (±2.5°C for comfort)
ƒ comfort zone depends on climate
30
40
%
Darwin
o
0C
10
20
30
40
50
30
15
0%
2
·
0
SET
30
Budapest
10
20
30
40
50
g/kg
20
·
30
22.3 24.8 27.3°C
40
11.5
10
8.5
g/kg
5
·
ET 25
o
0C
ET 20
-10
0
·
0
SET 3
20
%
10
35
·
10
ET 40
-10
g/kg
10
%
20
50
0
Images by MIT OCW.
Comfort zone
Standard Effective Temperature (SET)
ƒ SET isotherms on psychrometric chart
ƒ neutral temperature Tn = 17.6 + 0.31 x Tmonth (±2.5°C for comfort)
ƒ comfort zone depends on climate
40
%
.022
.020
75
.018
70
.016
65
35
ET
64 o
FW
SUMMER
55
WINTER
40
45
50
.014
68 o
FW
60
ET
BU
LB
%
20
BU
LB
.010
.008
.006
.004
0%
35 40 45 50
.012
55 60 65
70 75
.002
Pounds of Moisture Per Pound of Dry Air
%
.024
Absolute Humidity (Humidity Ratio)
.026
60
80
.028
85
80%
10
0%
Relative Humidity
80 85 90 95 100 105 110
o
Temperature F
Image by MIT OCW.
Comfort zone
Standard Effective Temperature (SET)
SET isotherms on psychrometric chart
neutral temperature Tn = 17.6 + 0.31 x Tmonth (±2.5°C for comfort)
comfort zone depends on climate
shift with MRT and air movement
.018
70
.016
65
.014
Original Location
60
55
35
40
45
%
20
50
.012
.010
.008
.006
.004
o
95 100 105 110
%
%
.018
.016
65
.014
60
%
20
55
35
40
45
35 40 45
.022
.020
70
Original Location
50
.012
.010
.008
.006
.004
10%
Temperature F
.024
60
80%
0%
10
75
.002
35 40 45 50 55 60 65 70 75 80 85 90
.026
50 55 60 65
70 75
80
o
Temperature F
85 90
Absolute Humidity (Humidity Ratio)
.020
80
.028
85
40
%
40
75
.022
Pounds of Moisture Per Pound of Dry Air
%
.024
Absolute Humidity (Humidity Ratio)
.026
60
80
Relative Humidity
.028
85
80%
0%
Relative Humidity
10
ƒ
ƒ
ƒ
ƒ
.002
10%
95 100 105 110
Image by MIT OCW.
Humid Air, Thermal Comfort
Reading assignment from Textbook:
ƒ “Introduction to Architectural Science” by Szokolay: § 1.1.3 +
§ 1.2
Additional readings relevant to lecture topics:
ƒ "How Buildings Work" by Allen: Chap 7 + pp. 58 - 60 in Chap 8
ƒ "Heating Cooling Lighting" by Lechner: Chap 4