What is BS EN 12898 - Emissivity of Glass in building about ?
BS EN 12898 is a European Standard on glass in buildings.
BS EN 12898 specifies a procedure for determining the emissivity at room temperature of the surfaces of glass and coated glass.
The emissivity is necessary for taking into account heat transfer by radiation from surfaces at the standard temperature of 283K in the determination of the U value and of the total solar transmittance of glazing.
The procedure given in BS EN 12898 is based on spectrophotometric regular reflectance measurements at near nominal incidence on materials that are non-transparent in the infrared region. Thus, it is not applicable to glazing components with at least one of the following characteristics:
- With rough or structured surfaces where the incident radiation is diffusely reflected
- With curved surfaces where the incident radiation is regularly reflected at angles unsuitable to reach the detector using regular reflectance accessories
- Infrared transparent
However, the method given in BS EN 12898 can be applied with caution to any glazing component, provided its surfaces are flat and non-defusing, and it is non-transparent in the infrared region.
Who is BS EN 12898 - Emissivity of Glass in building for ?
BS EN 12898 that explains determination of emissivity of glass in building can be used by:
- Glass manufacturers
- Engineers working on determining emissivity
- Constructors
- Building safety and control bodies
- Researchers
Why should you use BS EN 12898 - Emissivity of Glass in building ?
BS EN 12898 that explains determination of emissivity of glass in building takes account of Fourier Transform Infrared (FTIR) spectrophotometers where the spectral range is limited.
BS EN 12898 describes a method whereby spectrophotometers can be used to determine emissivity if they are able to measure up to the 24th ordinate point and if they satisfy a noise criterion for this spectral range. It allows the inclusion of data from the 25th ordinate point up to the 30th ordinate point.
By using BS EN 12898 best practice guidance, you will be able to effectively assess emissivity of glasses in buildings and reduce or increase heat transfer, as per requirement.
What’s changed since the last update ?
BS EN 12898:2019 is the UK implementation of EN 12898:2019. It supersedes BS EN 12898:2001, which is withdrawn.
The main changes compared to the previous edition are the following:
- Introduction of a method to determine the emissivity using Fourier Transform Infrared (FTIR) spectrophotometers where the spectral range is limited
- Provision of a new method for the calculation of corrected emissivity
- Clarification of rounding rules for normal emissivity