Targeted
LIGHT SHOULD BE DIRECTED ONLY TO WHERE IT IS NEEDED
Use shielding and careful aiming to target the direction of the light beam so that it points downward and does not spill beyond where it is needed.
FROM IDA FIVE PRINCIPLES OF RESPONSIBLE OUTDOOR LIGHTING – https://www.darksky.org/our-work/lighting/lighting-principles/
While much is to be said for computer aided design, I have found most outdoor lighting and street lighting requires a verification and confirmation to assure the light is properly targeted and the source is controlled for glare and intrusion and safety. Choosing the proper luminaire for the setting is an incredibly important part of this. In addition, assuring the aim and shielding is correct will yield a reduction in the wattage required because the shield is made to redirect light from the source onto the target area. No light is wasted. If you are concerned about energy, carbon emissions, and climate change then common sense says targeting a light and choosing a well designed luminaire will be very important. How much energy can be saved with the proper light design? I measured it at about 75%. Pretty low hanging fruit in the fight to reduce energy use, yes? Proper targeting also controls the intrusion into the environment from the blue spectrum, which is confirmed by science to cause 2-3 times the damage in the environment than the red end of the spectrum. Be cautious though, excess light at night, from any part of the spectrum is unnatural. The amount of light AND the spectral emissions both matter. Common sense and science meet!
Night Lights 