KEEPING OUT THE CHILL U-VALUE STABILITY IN 2 VS. 3 GLASS UNITS

摘要

The development of low-e coatings with lower and lower emissivity have led to a situation where the methods for declaration of U-values can be discussed, questioned and may have to be amended. The standard EN 673 is not sensitive enough for units with extremely low emissivity where the heat radiation loss is almost eliminated. The calculation of U-value is then much more dependent on how conduction and convection within the units are calculated. There is a risk that the current standard will mislead consumers in their choice between double and triple glazing when the units get similar declared U-values.