ISO 11855-2:2021

This document specifies procedures and conditions to enable the heat flux in water-based surface heating and cooling systems to be determined relative to the medium differential temperature for systems. The determination of thermal performance of water-based surface heating and cooling systems and their conformity to this document is carried out by calculation in accordance with design documents and a model. This enables a uniform assessment and calculation of water-based surface heating and cooling systems. The surface temperature and the temperature uniformity of the heated/cooled surface, nominal heat flux between water and space, the associated nominal medium differential temperature, and the field of characteristic curves for the relationship between heat flux and the determining variables are given as the result. This document includes a general method based on finite difference or finite element Methods and simplified calculation methods depending on position of pipes and type of building structure.