Handbook of air conditioning and refrigeration / Shan K

The inward heat flow from the inner surface of the indoor glass, from Eq. (3.74), is given as
Q RCi
A s
Selection of Glazing
� U � � o I t
h o
� 0.400 � 46.9
4.44
2. From Eq. (3.82), the temperature of the outdoor glass is
and the temperature of the indoor glass is
3. From Eq. (3.79), the transmittance for both panes is
and from Eq. (3.81), the solar heat gain coefficient for the double-glass window is
Then, from Eq. (3.84), the shading coefficient of this double-glass window is given by
4. From Eq. (3.80), the total heat gain admitted through this double-glass window per square
foot of sunlit area is
Q wi
A s
� � i I t 1
h o
SHGC oi � � oi � U� o
h o
� 0.135 �
HEAT AND MOISTURE TRANSFER THROUGH BUILDING ENVELOPE 3.39
� oi �
� 1
h a
� o� i
1 � � 2� 3
�� U
h o
0.40 � 0.189
4.44
� T o � T r�
� 33.5 1
4.44 � 1.75 � 100 � 76� � 40.29 Btu / h�ft2 (127.1 W/ m 2 )
Tgo � To �� �o It � �i It � QRCi A �� s
1
�
ho Rg 2�
� 100 � (46.9 � 33.5 � 40.29)� 1 0.035
�
4.44 2 � � 109.7�F
Tgi � Ti � QRCi A � s
1
�
hi Rg 2�
� 76 � 40.29 � 1 0.035
�
2.21 2 � � 94.9�F (34.9�C)
� U
h a � � i
SC � SHGCoi �
SHGCDSA 0.259
� 0.297
0.87
� SHGC oi I t � U(T o � T i) � 0.259 � 248 � 0.40(100 � 76)
� 64.2 � 9.6 � 73.8 Btu / h�ft 2 (233 W/ m 2 )
�
0.8 � 0.16
1 � 0.08 � 0.68
� 0.135
�� 0.40
� 0.40 � 1.75� 0.135 � 0.259
4.44
During the selection of glazing, the following factors should be considered: visual communication,
use of daylight, thermal comfort, summer and winter solar heat gain, street noise attenuation, safety