DIN EN ISO 11855-2:2026-05

DIN EN ISO 11855-2 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. This document includes Amendment 1 approved by CEN on 2023-05-14. This document EN ISO 11855-2:2021 + A1:2023 has been prepared by Technical Committee ISO/TC 205 "Building environment design" in collaboration with Technical Committee CEN/TC 228 "Heating systems and water based cooling systems in buildings", the secretariat of which is held by DIN (Germany). Since November 2024 the EN ISO 11855 series of standards at CEN has been assigned to CEN/TC 130 "Space heating and/or cooling appliances without integral thermal sources", the secretariat of which is UNI (Italy). The responsible national standardization committee is Working Group NA 041-01-69-15 AK "Integrierte Flächenheizungen und -kühlungen (SpA CEN/TC 130/WG 9 und ISO/TC 205/WG 8)" ("Integrated surface heating and cooling (Mirror committee CEN/TC 130/WG 9 and ISO/TC 205/WG 8)") at DIN Standards Committee Heating and Ventilation Technology and their Safety (NHRS).