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Solar Heat Transmission through Windows

Solar heat gain through windows with roller shades, vertical blinds and Venetian blinds

Sun Radiation through Windows

Heat gain from sun radiation through windows can be controlled with shades or blinds.

Solar Heat Transmission through Windows

Type of Shading

Transmitted Solar Energy
Reflected Solar Energy
Absorbed Solar Energy
Single or double glass without shading 75 - 80 10 - 20 10 - 20
Vertical Blinds 5 40 - 60 35 - 55
Venetian Blinds 0 23 77
Roller Shades < 25 15 - 80 20 - 65

Effect of Shading compared with unshaded Window

Solar Heat Transmission through Windows vs. Shading
Types of ShadingFraction of Gain through Unshaded Window
Unshaded Window 1.00
Inside roller shade - half-drawn 0.80
Inside roller shade - fully-drawn 0.62
Inside venetian blind 0.65
Canvas awning 0.30
Outside shading screen - solar altitude 20o 0.38
Outside shading screen - solar altitude 30o 0.25
Outside shading screen - solar altitude 40o 0.18

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    Design of Air Conditioning systems - heating, cooling and dehumidification of indoor air for thermal comfort.

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