This part of ISO 11855 specifes the basic defnitions, symbols, and a comfort criteria for radiant heating and cooling systems.The ISO 11855 series is applicable to water based embedded surface heating and cooling systems in residential, commercial and industrial buildings. The methods apply to systems integrated into the wall, foor or ceiling construction without any open air gaps. It does not apply to panel systems with open air gaps which are not integrated into the building structure.The ISO 11855 series also applies, as appropriate, to the use of fuids other than water as a heating or cooling medium. The ISO 11855 series is not applicable for testing of systems. The methods do not apply to heated or chilled ceiling panels or beams.