No, its not a cream to make green roofs grow faster. In the UK, DuPont has introduced Energain(R), a panel that mounts on the interior face of a building envelope and which uses phase change energy sorption and release in a wax-like medium to "slow down temperature increases within a room, reducing temperature peaks by as much as 12 degrees F or 7 degrees C, providing greater comfort for consumers and reducing the need for air conditioning. Conversely, as temperatures drop, the absorbed heat in the panels is released, slowing down the cooling of rooms and lessening the need to resort to heating systems."
The product takes the form of a "5mm aluminium-laminated panel, containing a copolymer and paraffin wax compound. It is installed on the interior walls and ceilings of a building, behind the plasterboard lining, together with a mechanical ventilation system. The rigid panel is similar in dimension to an ordinary plasterboard panel, ..."
Via:Dupont. Image credit::Dupont also (OK the pic looks like a commercial; but it's really difficult to come up with an interesting graphic of a thin shiny panel.)