As mentioned in the outdoor lighting post, according to the U.S. Department of Energy, commercial lighting can account for 15% to 50% (with a median of 35%) of a building’s annual energy consumption. Indoor lighting accounts for a majority of that statistic and also has a more diverse variety of lighting fixture types, lamp types and lighting design requirements. With that being said, a lighting retrofit designer must be well versed in available lighting retrofit options and design tools to make a lighting retrofit successful. The most common and cost effective retrofits in commercial applications are linear fluorescent lamp(s)/ ballast replacement with hi-lumen lamps and electronic ballasts, de-lamping, retrofit kits and relighting kits.
Re-lamping an existing fluorescent fixtures still using older 48” length T-12 lamps and magnetic ballasts can consume as much as 46 watts per lamp (40 watt T-12 with a 2-lamp magnetic ballasts), increase summer cooling costs and reduce occupant comfort due to humming noise and low frequency flickering. This is the easiest retrofit that can provide the quickest payback and can be performed with the existing fixture in place, from the room side of the ceiling and consists of removing the existing lamps, magnetic ballast(s) and installing an instant start or program rapid start ballast with hi-lumen T-8 lamps, such as the 25, 28 or 32 watt super T-8 lamps. For example, a four lamp fixture originally consuming 184 watts can now provide equal to increased lighting levels at 92-104 watts and can eliminate the heating load, low frequency flicker and humming noise of the old lamp/ ballast system (based on 25, 28 or 32 watt hi-lumen fluorescent lamps with a normal ballast factor of 0.89). If we also reduce the number of lamps in this example by de-lamping or permanently removing lamps from the fixture we can save a tremendous amount of energy as compared to the original system. Once again, our four lamp fixture originally consuming 184 watts can now provide slightly less or equal lighting levels, depending on lamp choice, at 46-52 watts per fixture. That is a 50-75% reduction in energy consumption utilizing the original fixtures with only lamp and ballast changes but no improvement in fixture efficiency.
The other retrofit option available is a retrofit kit which is available in many configurations but I am going to cover two main types, the recessed troffer retrofit kit and relighting kit. Both kits are more expensive than just re-lamping an existing fixture but offer the added benefit of improved fixture performance, improved light distribution and new fixture components. These can also be installed in the existing fixture from the room side of the ceiling. A retrofit kit reuses the existing fixture housing, lens door frame and lens and consists of a new semi-specular or highly reflective white reflector, lamp holders, electronic ballast and mounting hardware. Specifying a specular reflector will improve vertical distribution of a fixture and is a better choice for higher ceiling heights while the white reflector has a wider horizontal distribution and is a better choice for low to medium ceiling heights. To retrofit an existing fixture the installer would remove the internal parts of the existing fixture leaving only the exterior housing, lens and lens door frame and its original mounting. Next, the ballast is installed, lamp holders on each end of the fixture, then the new reflector is snapped into place with new lamps and finally the original lens is closed. On the other hand, a relighting kit reuses only the existing fixture housing and original mounting and includes a new reflector, ballast with mounting tray, lamp holders, lens door frame and lens. The installation is similar to the retrofit kit except the installation of the new lens and lens door frame. Both kits can offer the same energy savings as the de-lamping example above but with improved fixture efficiency that in conjunction with a new layout can reduce the number of fixtures and the energy consumption even more. The relighting kits offer a refreshed look to the interior with new lenses and are also available in LED with dimming options and integrated controls.