Large panels are used to control the indoor temperature, by cooling as well as by heating, in several types of buildings. The panels are made out of two corrugated stainless steel foils, seam welded on the perimeter and spot welded at many places on the area. Water at controlled temperature circulates in this cushion. These panels are either installed as conditioning ceilings or on walls. In well-insulated buildings, the power required to control indoor temperature is rather low, and a small temperature difference between the panel and the indoor environment suffice to deliver or absorb the required heat. The paper presents the panel itself and its use in residential and non-residential buildings, as well as some industrial and research implementations.