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HEM November/December 1994 - Home Energy Magazine Online November/December 1994

Home Energy Magazine Online November/December 1994

MARKETPLACE

Fixing the Fixtures

Dedicated fixtures designed explicitly for the compact fluorescent lamp offer an effective and permanent solution for energy-efficient residential lighting.

by Michael Siminovitch and Evan Mills

Michael Siminovitch is a staff scientist with the Lighting Systems Research Group and Evan Mills is assistant director of the Center for Building Science, both at Lawrence Berkeley Laboratory, in Berkeley, California.

With U.S. sales approaching 50 million lamps per year (and 250 million globally), compact fluorescent systems are increasingly popular. However, efforts to promote their use in the residential market have mostly been limited to utility rebate programs for screw-based lamps. Concerns about performance and economics suggest that integral screw-based (as opposed to modular pin-based) technologies are, at best, a short-term approach to the ultimate, widespread residential application of the CFL.

The fundamental reason that screw-based CFLs are only a temporary solution is the so-called "snapback" effect: When these units burn out--or perhaps even sooner--they can easily be replaced with the inexpensive and inefficient incandescent lamp, eroding the conservation potential. This occurs in part because consumers generally will not keep $10-$15 screw-based CFLs in their home inventory, and because of the likelihood of unacceptable performance for this type of a CFL strategy.

The push for affordability has led to the availability of some inexpensive screw-based CFL products that have marginal quality, leading to premature failures and consumer dissatisfaction. Some CFLs are now being made smaller so that they fit into more existing home fixtures (see "Downsizing the CFL," HE Jan/Feb '94, p. 5). But reducing dimensional characteristics can result in constricted ballast compartments, compromising quality and operation of the electronic components.

Part of the problem stems from the fact that most existing home fixtures are designed for the incandescent A-lamp, which has a very different luminous distribution than the more linear and non-symmetrical CFL. Replacing an incandescent A-lamp with a CFL noticeably changes the optical distribution of the overall fixture, sometimes reducing perceived brightness. Efficiency should be assessed using the total lumen output and light distribution of the fixture system where the lamp is installed, not just the output of the screw-based assembly by itself.

Since consumers are interested in the total light output and the quality of the illumination, component efficiency (for instance lamp efficacy, measured in lumens per watt) is not as important as actual system performance characteristics--how well a lamp system works when inserted into a fixture. When retrofit into existing fixtures, some CFLs perform dramatically differently from others.

Pin-based lamps in dedicated fixtures, on the other hand, allow for easy re-lamping with maximum lifetime energy savings and economic benefits. Dedicated fixtures can be designed to optimize the optical performance and appearance of the CFL.

Taking Advantage of Technology

Screw-based retrofit systems typically combine a lamp, a ballast and a familiar threaded "Edison" base for "quick-and-dirty" connection with existing incandescent sockets inside fixtures. The lamp may be integral with the ballast or removable for re-lamping (see Figure 1).

Dedicated systems include a fixture whose elements (electrical connections, ballasting, and optical control) are integrated. A separate, replaceable pin-based lamp can be positioned appropriately to maximize optical distribution and maintain an optimum thermal environment (lamp overheating can result in up to a 25% reduction in light output). As in a commercial fixture, the pin-based lamp plugs into a socket within the fixture.

Fixture geometry can be designed to maximize the optical distribution of the unique compact fluorescent shape, thereby maintaining high fixture efficiency. When the lamps burn out, the fixture can be re-lamped only with a pin-based CFL, for continued savings. A pin-based compact fluorescent lamp is much cheaper than the more complicated screw-based system, so consumers are more likely to stockpile a few. Another benefit is that less solid waste is produced upon disposal, and mercury recovery is less expensive (approximately 50cents for the bulb alone, versus $1 for an integrated lamp).

Other advantages of pin-based systems include greater ability to address power quality issues in the ballast, and easier implementation of dimmable ballasts.

Moving the Market

The only way to ensure that CFL technology's conservation potential is realized is to replace both the incandescent lamp and socket with a dedicated fixture system. Looking at the history of lighting reveals several successful examples of this approach; one is the lighting of commercial interiors. Consider the way pin-based long fluorescent lamps displaced incandescents in the commercial sector in the 1940s, and pin-based halogen lamps swept into popularity in homes in the 1980s.