CFLs in Recessed Downlights: Technical Challenges
Recessed downlights are the most popular residential lighting fixture in the United States representing about 12 percent of installed residential lighting fixtures and 15 percent of total lighting energy use nationwide. We estimate 400 million recessed downlights are currently installed in American homes, almost all using incandescent light sources. In the year 2000, only 0.44 percent of recessed cans sold were hard-wired for using pin-based CFLs. Recessed downlights consume energy in three ways. First, their incandescent light sources use energy directly, drawing 65 to 150 watts. Second, they consume energy indirectly by adding heat from their light sources to air-conditioning loads. Third, since most are not airtight, they also consume energy indirectly by allowing conditioned air to escape into unconditioned areas above the downlights, such as attics. PNNL calculated potential energy savings and found that if a 65W incandescent non-airtight downlight is replaced with a 26W CFL ICAT downlight operated at 3 hrs per day savings will be 126 kWh/yr. Early reflector CFLs have had high return rates primarily because of failure due to thermal related stress. A PNNL laboratory test of ten commercially available R-CFLs selected from retail store shelves showed almost all operated above their manufacturer rated maximum operating temperatures when they were installed and tested in ICAT downlights in a simulated insulated ceiling apparatus. DOE asked PNNL to investigate the development and introduction of both pin-based and screw-based CFLs for use in ICAT fixtures. PNNL invited manufacturers to submit lamps to a procurement program. PNNL conducted short- and long-term thermal testing of the lamps to measure performance parameters affected by elevated temperatures. 8 out of 10 R-CFLs (secrew-based lamps) failed the long-tem testing. Five out of nine CFL-ICAT (pin-based CFL) fixtures passed the long-term test, surviving a full year of operation in a simulated insulated ceiling apparatus, while maintaining at least 80% of initial lumens at 40% of rated life. Of those five products, two were withdrawn from the market due to poor sales, probably because of the high prices on the products. Three remain on the market. PNNL plans to initiate another R-CFL technology procurement in the winter of 2004/2005 to bring more high-quality R-CFL models to market. PNNL developed a number of design ideas for improving the thermal performance of pin-based CFL ICAT downlights for use in future activities.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 965624
- Report Number(s):
- PNNL-SA-43941; BT0303000; TRN: US200919%%654
- Resource Relation:
- Conference: Right Light 6, 6th International Conference on Energy Efficient Lighting, May 9-11, 2005, Shanghai, China., Paper No. RL6 #029
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AIR CONDITIONING
ATTICS
DESIGN
LIGHT BULBS
LIGHT SOURCES
MANUFACTURERS
MARKET
PERFORMANCE
POTENTIAL ENERGY
PRICES
PROCUREMENT
SALES
TESTING
THERMAL TESTING
Compact fluorescent lamp
CFL
recessed downlight
reflector compact fluorescent lamp
R-CFL
airtight
insulated ceiling
ICAT
technology procurement
thermal testing
lighting fixture
recessed can
residential lighting