A Revolutionary Lighting Technology... 15%-35% Return on Investment: Nature's Lighting daylighting systems pay for themselves several times over in bottom line energy costs - both in lighting and air conditioning savings. People and Building Performance: Natural light improves morale, safety and productivity while reducing errors. People are better able to distinguish object details, location and color. Preserve the Environment: At just one of its stores, Wal-Mart helped cut an estimated 618,200 pounds of atmosphere-warming carbon dioxide, 1,793 pounds of nitrogen oxides and 1,076 pounds of sulfur dioxide from being produced by electric generating stations annually.