Energy-Efficient Torchieres for Residential Applications

Figure 1. Infrared thermograph of a CFL fixture left) and a halogen fixture.

Over the past 5 years, the Center's Lighting Lab has been pioneering the effort to replace standard residential lighting fixtures with hardwired compact fluorescent lamp (CFL) fixtures. One type of fixture under development is a novel torchiere indirect uplight using a CFL. Preliminary studies measured these CFL torchieres photometrically and compared their performance to that of standard tungsten halogen sources. Measurements made of these systems include goniophotometry, infrared thermography and power quality analysis. Goniometric data and power assessments indicate that using compact fluorescent lamps instead of standard tungsten halogen sources can result in significant lighting energy savings. The Lighting Lab is in the process of setting up a consortium between large lamp, ballast and fixture companies to produce a dedicated CFL torchiere which uses only 55 Watts of power, but produces more light than its 300 Watt halogen counterpart.

Major Savings Opportunities
There has been a significant increase in sales of imported torchiere systems in the American market. These indirect lighting systems use tungsten halogen sources in the 300- to 500- Watt range. Imports of torchiere systems have resulted in one of the largest increases in residential lighting energy use and represent a significant challenge to energy-efficiency programs throughout the country.

The 300-Watt halogen torchiere fixture is currently one of fastest selling portable fixture types in the United States. Recent studies have estimated that halogen torchieres are now consuming more energy than CFLs are saving in the U.S. To counter this erosion of the progress obtained by years of demand-side management programs and related governmental and utility conservation activities, we need to rapidly develop energy-efficient alternatives to this fixture using compact fluorescent systems. We have produced a set of torchiere systems using efficient CFL sources and are optimizing them photometrically. Manufacturers hope to have production of prototype fixtures on the market early next year. While the initial price of the CFL torchiere will be around $35 more than halogen fixtures, the total payback over the life of the fixture from energy savings will nearly $200 (for a 300W halogen vs. a 55W CFL assuming a fixture life of 10,000 hrs and an energy cost of $0.08/kWh).

New Designs and Results
In the first phase of this study, we measured the performance of a standard dimmable torchiere system using a 300-Watt tungsten halogen source. The system was characterized using a goniophotometer, which generates total lumen output and candlepower distribution data [Summer 1995, p.4]. Efficacy, fixture efficiency, power factor and total harmonic distortion were obtained over the entire dimming range. In the second phase, we will modify a standard torchiere to accept a range of CFL sources and reflector systems.

Photometric data shows that the standard halogen torchiere has an efficacy ranging from 2 to 12 lumens per watt (LPW) depending on the dimming level. Preliminary results indicate that the efficacy for compact fluorescent systems is 5 times that of the halogen torchiere at full power and increases to nearly 30 times the halogen efficacy as dimming occurs. This is because halogen efficacy drops off dramatically over its dimming range while the CFL efficacy is fairly constant. Effective lumen matches have been achieved using a variety of CFL sources. The power quality, as compared to the dimmed tungsten halogen, improved significantly with a CFL. The dimmed tungsten halogen yielded power factors less than 0.2 and a THD approaching 200%. An infrared thermograph camera was used to compare the CFL prototypes to the standard halogen torchiere (see Figure 1). The IR photo not only illustrates how much energy is wasted on heat in the halogen fixtures, but also indicates the potential fire danger of these fixtures when placed next to combustibles such as drapes.

--Michael Siminovitch and Erik Page

Michael Siminovitch
(510) 486-5863
Erik Page
(510) 486-6435
Building Technologies Program
(510) 486-6940 fax

This research is supported by DOE's Office of Building Technologies, State and Community Programs.