According to this article, an emphasis on evaluating whether a building is "green" and sustainable has been developing since 2000. Some green buildings have achieved 40 per cent energy reduction and 30 per cent water reduction over similar non-green buildings. Some green building employees are more productive because out-gassing from building materials is reduced. A green building is estimated to increase costs by 0.8 per cent. Green concepts must be integrated in building design for the greatest savings. For example, building orientation can reduce lighting needs and the cooling needed to remove heat generate by these lights. Older buildings need to be upgraded to be green in order not to lose value.