What is ISO 11855-3 about?
ISO 11855-3 is the third part of multiple series that establishes a system design and dimensioning method to ensure the heating and cooling capacity of the radiant heating and cooling systems.
Who is ISO 11855-3 for?
ISO 11855-3 on embedded radiant heating and cooling systems is useful for:
- Construction industry
- Civil engineer
- Architect
- Manufacturer installer or supplier of building material
- Building contractor, operator, investigator, manager
Why should you use ISO 11855-3?
The floor heating system saves space as it is installed underfloor and it’s safe. ISO 11855-3 helps you determine heating surface area, type, pipe size, pipe spacing, supply temperature of the heating medium, and design heating medium flow rate.
To ensure the heating and cooling capacity, ISO 11855-3 specifies the design and dimensioning methods of radiant heating and cooling systems.
What’s changed since the last update?
BS EN ISO 11855-3:2021 supersedes BS EN ISO 118553:2015, which is withdrawn.
This second edition cancels and replaces the first edition (ISO 118553:2012), which has been technically revised.
The main changes compared to the previous edition are as follows:
- The Scope clause was modified, series-related information has been moved to the introduction section
- Normative references were modified
- Informative references have been moved to the Bibliography
- Annex A was added for the calculation of the thermal resistance of the insulating layers

