ISO 18566-3:2017 specifies the design of ceiling mounted radiant panels. ISO 18566-3:2017 is applicable to water-based heating and cooling panel systems (free hanging) in residential, commercial and industrial buildings. The methods apply to systems mounted to the ceiling construction with an open air gap. ISO 18566-3:2017 applies to all types of prefabricated radiant panels that are part of the room periphery. ISO 18566-3:2017 does not cover panels embedded into ceiling, wall or floor structures without open air gap and hybrid (combined thermal radiation and forced-convection) ceiling panels.