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Insulation classification for various types of construction

Requirements for maximum heat loss

NS-EN 12828: 2012 (*) specifies rules for maximum heat loss. The requirements are given in six insulation classes depending on operating time and the difference between operating and ambient temperature.

A spill factor can also be considered, so that one takes into account that the heat loss from insulated pipes through heated rooms contributes to the heating of these. One should then be aware that reducing the insulation thickness on this basis can lead to not having full control over the heat dissipation in all parts of the system. The consequence may then be too high a temperature in some areas.

Calculation programs

Calculation programs and tables 

The table below provides an overview of which insulation classes will normally apply to different types of systems and parts. The current class can be found from the diagram. Depending on the installation type and part, the relevant product is then selected.
Based on the given assumptions, the Rocktec program can calculate both the insulation class and the required thickness.

Heating system


Distribution cables and equipment in heated rooms

Klasse 3

Distribution cables and equipment in unheated rooms

Klasse 4

Hot tap water


Distribution and circulation pipes in heated rooms

Klasse 4

Distribution and circulation pipes in unheated rooms

Klasse 5

Ventilation system


Air ducts in heated rooms

Klasse 1

Air ducts in unheated rooms

Klasse 3


(*) The guide to TEK 17 refers to NS-EN 12828 for dimensioning of thermal insulation for technical installations. The standard was revised in 2012, but no changes were made to the insulation requirements.

(Kilde: Rockwool)