Abstract: An energy-saving cover apparatus for use in homes, mobile homes or any building in general, having room air registers. The cover apparatus is intended to solve the problem of losing heated room air through inadequately closed louvers of the conventional room air register when another heating system is being used to heat up the room. The apparatus is of inexpensive construction and can be quickly attached to the face of the conventional room air register. The apparatus is comprised of a cover means and a register attachment means. The cover means is described in two embodiments, firstly, a closed cell cellulose fibrous material is adhesively attached to a solid material on the frontside and suitably sized to fit the face of the conventional room air register. The register attachment means for this construction is a latching mechanism having a cover latching shank portion and a register attachment portion.