The Problem: Common residential exterior light fixtures that allow light pollution, light trespass and energy waste. Replacement of such fixtures (especially multiple exterior fixtures) can be prohibitively expensive.
The Solution: A light bulb with louvers designed into the sealed bulb envelope to keep light directed below the horizontal plane to meet modern full cut-off light fixture standards. When this louvered full cut-off bulb is placed in an older, exterior light fixture, light is directed towards the ground where it is needed rather than the sky where it is wasted.
19 U.S. states(1) have or are in the process of addressing light trespass and light pollution with requirements for full cut-off light fixtures on new or replacement structures. Many municipalities and counties independently address light pollution issues with standards exceeding those of the state. Most zoning/ordinances pertaining to light trespass and light pollution have grandfathered older, non-conforming exterior light fixtures due to the significant costs to replace these older fixtures with newer, full cut-off fixtures. With the louvered full cut-off light bulb, many of these older fixtures can meet newer lighting ordinances simply by changing out the light bulb rather than changing out the light fixture. Ordinance requirements and benefits are met at a much lower cost with light bulb replacement rather than light fixture replacement.
The louvered full cut-off light bulb is built around existing light bulb technology - either compact fluorescent (CFL) or light emitting diode (LED). The design shown the accompanying figure is based upon a CFL bulb. Opaque, non-reflective plastic louvers are stacked around the light source with a geometry that insures that no direct light escapes the bulb above the horizontal plane. The light source and louvers are then sealed in a transparent plastic envelope above the bulb base. The sealed unit simply replaces a standard bulb in a non-conforming light fixture.
The market potential for this louvered full cut-off light bulb design is significant. Most residential units have multiple exterior light fixtures with few of those fixtures currently meeting the newer light pollution/trespass standards. As zoning regulations pertaining to light pollution, nighttime glare and light trespass expand, the market potential should only grow.