When evaluating the thermal insulation performance of a glass product,we usually know that clear& tinted single piece glass is 5.84,Single silver low-E insulated glass 1.8,and double silver low-E is 1.55-1.65.The lower the value,the better thermal insulation performance the glass has.
But What does the value mean and the measurement unit?
Actually the measurement unit is W/M2.k,which means watt/square meter/Kelvin,it’s under same confirmed air condition,the heat transfered throught the glass products.
While even this measurement unit,there’re many different conditions depend on different client.
insulated glass-heat transfer-morn bm
The most widely used condition is American LBNL Ashare NFRC 100-2010 SUMMER standard:
Room temperature: 24°
Outside temperature: 32°
Glazing oriented windward, wind speed: 2.75 m/s
Sky temperature: 32°
Sky emissivity: 1.0
Incident solar power: 0 W/m2
NFRC 100-2010 winter standard:
Room temperature: 21°
Outside temperature: -18°
Glazing oriented windward, wind speed: 5.5 m/s
Sky temperature: -18°
Sky emissivity: 1.0
Incident solar power: 0 W/m2
While in European areas,they use another standard:EN673,there’s no summer and winter difference as there’s not big difference between winter and summer temperature.
Despite W/M2.K,there’s another measurement unit that shows the thermal conductivity :ft2•h•°F/BTU ,which means hour/square foot/°F.
It’s quite different unit.Sometimes clients mentioned glass unit is 0.3,many sales don’t believe this and think it must be incorrect and the glass U v value couldn’t be this low.While what the client mentions is hour/square foot/°F,not W/m2.k.
To transfer the unit, 1hour/square foot/°F =5.68w/m2.k,so don’t make mistake.
Morn is your turnkey architectural glass manufacturer supplying all kinds of tempered glass,laminated glass and insulated glass,welcome contact us for more info.
Download this article here:What’s the thermal conductivity measurement unit?
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