This is also true for residential street lighting - when properly beamed to the ground , the street will be lit sufficiently, with little light wasted on lighting up our bedrooms and homes. Unshielded rural lighting is simply wasted light - light travels miles in all directions instead of illuminating the farm grounds. The same can be said for most billboard lighting - the vast majority of that light is simply beamed into the sky . Properly shielded overhead lighting could do the same job with fewer lumens and thus at a lower cost. This excess lighting appears mainly as glare, causing eye fatigue and diminishing the human eyes' ability to see in darkness.
Safety is compromised.
Unshielded, glaring illumination often shines into homes. It is also difficult to see someone standing underneath a bright, outwardly directed, light. That same light directed downward to the door and its immediat e surroundings would provide far better security . Glare defeats both safety and security. The long-term savings in money and energy demands are obvious.