Internally replenished gas-containing enclosures are described. Such enclosures include a replenishing gas source internal to the enclosure, wherein the gas source comprises a gas contained within a permeable membrane. Exemplary gas sources include a plurality of bubbles and pouches. Materials useful for the permeable membrane include glass, glass ceramics, metals, metal oxides, polymeric films, as well as combinations of such materials. The gas source may be located within the enclosure or it may be incorporated into a resin (e.g., an adhesive or a gasket) positioned between sections of an enclosure. Methods of internally replenishing an enclosure are also described.