DIN EN ISO 11855-4:2026-05

DIN EN ISO 11855-4 allows the calculation of peak cooling capacity of Thermo Active Building Systems (TABS) - Type V according to ISO 11855-1, based on heat gains, such as solar gains, internal heat gains, and ventilation, and the calculation of the cooling power demand on the water side, to be used to size the cooling system as regards, for example, the chiller size, fluid flow rate. This document defines a detailed method aimed at the calculation of heating and cooling capacity in non-steady state conditions. It is part of the ISO 11855 series of standards. This series describes an embedded system that is incorporated into the building structure. Therefore, surface heating and cooling systems with open-air gaps that are not incorporated into the building structure are not covered by this series of standards. The ISO 11855 series of standards apply to water-based embedded surface heating and cooling systems in buildings. It applies to systems that use not only water but also other liquids or electricity as heating and cooling media. The ISO 11855 series is not applicable for testing of systems. The methods do not apply to heated or chilled ceiling panels or beams. This document includes Amendment 1 approved by CEN on 2023-05-14. This document EN ISO 11855-4:2021 + 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). This document includes Amendment 1 approved by CEN on 2023-05-14. 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).