advanced search

It's Not Easy Being Green

Jul 1, 2008 12:00 PM, By Carla Gallina, Lighting Designer

When evaluating lighting performance, it's crucial to look at the operating conditions of the system as a whole and not focus on the performance of individual components, such as the lamp, ballast, transformer, or luminaire. In this article, MR16/IR and 42W PL-T lamps are installed in representative downlights — each with a respective integral transformer and ballast supplied by the luminaire manufacturer. Independent Test Lab (ITL) reports for each downlight along with published manufacturer's lamp performance data are used for the comparison shown in (click here to see Table 3). The 50MR16/IR/FL35/C lamp installed during test ITL58960 is not the lamp of choice. A candela ratio from the lamp manufacturer's data provides a look at how the luminaire would likely perform if the 37MR16/IR/FL35 lamp were installed in its place.

The 37W MR16/IR downlight outperforms the 42W PL-T downlight on many levels. In summary, the halogen system consumes less energy, and its initial candlepower is much higher, even though the CFL system efficacy is greater. At 40% of rated lamp life, the total candlepower of the halogen system remains somewhat constant at 9,169, whereas the CFL total candlepower is reduced to 7,485. When trimmed to 90%, the MR16/IR lamp operates at 33.6W, providing similar light to the PL-T. Lamp life is also extended to 20,000 hours. Dimming a CFL will reduce the consumed energy and light output, but it will not extend its lamp life beyond 12,000 hours. CFLs contain about 4 milligrams of mercury. Halogen lamps do not contain mercury. The halogen lamp provides better color quality than the CFL, is less expensive to dim, and is easier to control.

The best application for reflector lamps in general and for the MR16/IR lamp in particular is installed in a simple track-mounted lamp holder or mono-point used for accent lighting in retail and commercial spaces. In the following, the performance of the 25W Integrated PAR 38/CDMI/FL25 (25W CDMI) is compared to the 35MRC/IRC/NFL24 halogen lamp. Refer to the article in the October 2007 issue of EC&M, “Using State-of-the-Art Screw-Based Lamps,” for a description of retail accent lighting and a summary of the 25W self-ballasted ceramic M-H (CDMI) lamp.

In this comparison, the 37W MR16/IR used in the downlight evaluation is replaced with a 35W MR16/IRC, because it is from the same manufacturer as the 25W CDMI. It's assumed that lamp data provided from a single manufacturer will be consistent due to similarities in testing methods, test equipment, and performance documentation — and will result in a more reliable comparison than lamps from different manufacturers. The 25° narrow flood distribution was selected because it is the most common and versatile lamp used for retail and commercial accent lighting ( (click here to see Table 4)).

At first glance, this might be considered a dubious comparison, because the 35W MR16 has a lower CBCP, lower total candlepower, and higher wattage than the 25W CDMI. But as in any green analysis, it's important to consider all of the life-cycle operating characteristics and power requirements before formulating a conclusion.

At 40% of rated lamp life, the CDMI delivers 69% of its initial light output, which continues to degrade prior to end of life. If, as in the downlight example, we extend the MR16/IR lamp life to 20,000 via high end trim, then at 40% of rated life (4,200 hours of burn time) the halogen lamp will operate at 31.5W — and the total candlepower is only slightly less than the candlepower of the CDMI.

Want to use this article? Click here for options!

© 2012 Penton Business Media, Inc.

---

Acceptable Use Policy blog comments powered by Disqus

Browse Back Issues Select an Issue November 2011 October 2011 September 2011 August 2011 July 2011 June 2011 May 2011 April 2011 March 2011 February 2011 January 2011 December 2010 November 2010 October 2010 September 2010 August 2010 July 2010 June 2010 May 2010 April 2010 March 2010 February 2010 January 2010 December 2009 November 2009 October 2009 September 2009 August 2009 July 2009 June 2009 May 2009 April 2009 March 2009 February 2009 January 1, 2009 December 2008 November 2008 October 1, 2008 September 2008 August 2008 July 2008 June 1, 2008 May 2008 April 2008 March 2008 February 2008 January 2008 December 2007 November 2007 October 2007 September 2007 August 2007 July 2007 June 2007 May 2007 April 2007 March 2007 February 2007 January 2007 December 2006 November 2006 October 2006 September 2006 August 2006 July 2006 June 1, 2006 May 1, 2006 April 2006 March 1, 2006 February 2006 January 2006 December 2005 November 2005 October 2005 September 2005 August 2005 July 2005 June 2005 May 2005 April 2005 March 2005 February 2005 January 2005 December 2004 November 2004 October 2004 September 2004 August 2004 July 2004 June 2004 May 2004 April 2004 March 2004 February 1, 2004 January 1, 2004 December 1, 2003 November 1, 2003 October 1, 2003 September 1, 2003 August 1, 2003 July 1, 2003 June 1, 2003 May 1, 2003 April 1, 2003 March 1, 2003 February 1, 2003 January 1, 2003 December 1, 2002 November 1, 2002 October 1, 2002 September 1, 2002 August 1, 2002 July 1, 2002 June 1, 2002 May 1, 2002 April 1, 2002 March 1, 2002 February 1, 2002 January 1, 2002 December 1, 2001 November 1, 2001 October 1, 2001 September 1, 2001 August 1, 2001 July 1, 2001 June 1, 2001 May 1, 2001 April 1, 2001 March 1, 2001 February 1, 2001 February 1, 1995 January 1, 2001 December 1, 2000 November 1, 2000 October 1, 2000 September 1, 2000 August 1, 2000 July 1, 2000 June 1, 2000 May 1, 2000 April 1, 2000 March 1, 2000 February 1, 2000 January 1, 2000 December 1, 1999 November 1, 1999 October 1, 1999 September 1, 1999 August 1, 1999 July 1, 1999 June 1, 1999 May 1, 1999 April 1, 1999 March 1, 1999 February 1, 1999 January 1, 1999 December 1, 1998 November 1, 1998 October 1, 1998 September 1, 1998 August 1, 1998 July 1, 1998 June 1, 1998 May 1, 1998 April 1, 1998 March 1, 1998 February 1, 1998 January 1, 1998 December 1, 1997 November 1, 1997 December 1, 1996 November 1, 1996 October 1, 1996 September 1, 1996 August 1, 1996 July 1, 1996 June 1, 1996 May 1, 1996 April 1, 1996 March 1, 1996 February 1, 1996 January 1, 1996 December 1, 1995 November 30, 1995 November 1, 1995 October 1, 1995 September 1, 1995 August 1, 1995 July 1, 1995 June 1, 1995 May 1, 1995 April 1, 1995 March 1, 1995

browse e-newsletters