The same floodlight fixture, the one on the left pointing out and the one on the bottom pointing down.  Which illuminates the area better?  

 

 

 

 

 

Glare from things like street lights actually makes it harder for some people to see, since it causes eye pupil constriction—leading to unsafe driving conditions, especially among older people, the resolution says. The AMA estimates that “40 percent of the light emitted from standard streetlights” is glare light—or completely wasted electricity. “This contributes to excess carbon dioxide production and possibly global warming,” the group declares. 

More than $10 billion could be saved if cities around the country used eco-friendly streetlights instead, the medical group concludes. One solution—adopted by an increasing number of cities—is to enact outdoor light laws and replace old-fashioned streetlights with non-glare or “fully shielded” streetlights, which shed light where it’s needed.

And business owners who pump a lot of money into outdoor signage insist that increased wattage is frequently all that sets them apart from the competition.  In the pictures below, notice that the amount of light on the ground is about the same, but without the glare.

 

But there is such a thing as shining too much light on a subject. The Illuminating Engineering Society of North America studied commercial lighting and concluded that "many companies use five times the amount of light necessary for effective marketing." "Business lights are out of control," says Nancy Clanton, a lighting designer who helped the I.E.S. draft new guidelines recommending that outdoor lighting be reduced as much as 80%.

 

Street lights that shine down only (called Full Cutoff) put as much light on the ground as do the Cobrahead lights.