LPS and HPS lamps are the most efficient and are the best choice for residential street lighting when fitted within shielded fixtures. These bowl lenses can be refitted with flat lenses that will improve downward illumination and reduce glare. We know to our cost the fallacy of this ideology when we became aware of the more well known types of pollution such as air and water and foods. Light pollution is another dimension of the same problem that can be remedied for less than the cost of the wasted light itself. Any light beyond this distance is effectively being wasted as side-light and therefore causing glare and skyglow.
Any light emitted upwards is of course being wasted completely.
However, there are very few lighting manufacturers willing to release measurements of the lighting intensity patterns of their products to the public. And virtually no-one, it seems, even thinks of measuring how much light is emitted upwards. In 1997 nearly five million dollars worth of the electricity used for public lighting in South Australia was wasted. Since then the problem has got worse. Collectively paid for by us.