In order to achieve maximum transparency in their building projects architects plan larger facades and larger window areas. These glass surfaces have the disadvantage that in winter they form a cold surface and in summer the sun heats the room. Therefore, they have the potential to be used as a surface heating and cooling. To be able to use an IGU as a heater, the temperature must be distrib-uted over the surface of the glass. Existing solutions rely on heating wires between the panes of a laminated glass but these are visible for the user. To create an invisible system, the cavity can be used. By filling the cavity with helium instead of argon or krypton, temperatures can be distributed over the pane due to the good thermal conductivity of helium. Content of this paper is the gas tightness and interaction of helium in an IGU with standard edge seal and the first functional tests for heating and cooling with helium.