Radiant energy not passing trough a laminated glass

[canticorum]

Dear friends:


A glass dealer is selling the following laminated glass:
4 mm Solex glass + ice color pvb + 4mm claer glass,
featuring that radiant energy does not pass across the glass. (this glass only permitts transmission heat gain as a solid wall).

Always I have believe that radiant energy travels across any glass.

Have me been wrong for many years?
Thanks for your answer.

Canticorum

 

[IRstuff]

Depends on which radiant energy you're talking about. Obviously, the glass must still pass the radiant visible energy. However, window glass does not pass much beyond 2um. Solex:

http://www.ppg.com/gls_residential/share/hom_soltint.htm#solexia

supposedly only passes about 1/2 of the near-infrared radiant energy and should pass essentially no energy above 2 um.

TTFN

 

[GMcD]

You also have to consider the heat transferred by conduction through the glass/laminate material/glass sandwich. If the glass is exposed to the sun, the outside surface temperature of the glass will be hotter than the ambient air temperature, and this heat will conduct through, and heat up the inner pane of glass. If the inner pane of glass has a surface temperature more than 6C higher than the room ambient temperature, then the glass will start acting like a radiant heating panel to the occupant. Same thing happens in winter. The glass has to be selected for both the thermal insulation properties as well as the light transmission properties (infra-red to ultra-violet range). It may be likely that the laminated glass product will filter out the infra-red long wave spectrum, but it will have poor insulating/thermal resistance properties without an air gap.