Princess Alexandra Hospital NHS Trust, Harlow, Essex, is currently carrying out a large LED lighting project within the hospital. As Bill Dickson, the trust’s environment Manager, explains: “The trust will be replacing most of the lighting in corridors, as these are the highest usage of energy, as they are used 24/7, so the lighting is on all the time. |
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| “The first corridor to be done and monitored was the children’s ward corridor, as families are in and out of the ward at all times of the day. On average this corridor was using 53kw per day - it is now using an average of 5kw. Even before this project the corridor lights would be turned off during day light as there is plenty of natural light coming through the windows. |
| “All the lift lobbies have been completed, together with the outpatients department and X ray corridor.” Bill adds: “The cost of this project is £165,000, with an 18-month payback.” Other recent healthcare contracts by Armadillo LED include: Addenbrookes Hospital, Cambridge, Colchester Hospital, Bedford Hospital, and health centres in Peterborough and Gloucester. For more, call Armadillo LED on 0845 060 4000 or visit www.armadilloled.com |
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| ArmadilloLED have been providing and involved in creative, cost effective LED design solutions for over 25 years and by amalgamating its expertise from all fields, offering a complete package to meet the increasing demand for innovative electronic and solid state lighting products. LED lighting Source (Light-Emiting Diode)is more than just a replacement for traditional light sources. Not only is it more energy efficient, virtually maintenance-free, much longer lasting, and great for meeting your carbon reduction goals: it is also a professional solution for lighting designers, offering an infinite combination of colours for imaginative interior and exterior lighting, including finely controlled colour changing effects. With the recent addition of amazing new lighting fittings, general room lighting is now achievable purely with LED technology - an application that until very recently has only been practical and effective with assistance from traditional light sources. Of course, the same fine control applies, with options for variable colour temperatures from cool, crisp whites that are great for task lighting, to warm, relaxing whites that work well in relaxed areas and in the home or work place. |
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| Armadillo's extensive resources and experience allow us to support you throughout your lighting project, from initial concept through to completion. Our additional support for major projects provides full in house DIALux light planning from Armadillo upon request. In short, Armadillo offers you a combination of innovative technology, aesthetic appeal and manufacturing excellence that opens up opportunities to create stunning interior and exterior lighting. |
| Designed to embrace the future for lighting solutions delivered for you today by Armadillo LED. Energy efficiency as standard and huge light performance with up to 85% savings, long life and massive maintenance savings. Products already delivering >85LPW and a development road map to >138LPW, without the need to go past 350Ma to achieve these impressive light outputs. See our full LED Light Exterior Range |
| LEDs are the future lighting platform for all designers and architects. Armadillo LEDs are now used in mood lighting, accent lighting, landscape lighting, building illumination and so many other applications. Armadillo LEDs are economic, aesthetically pleasing, environmentally friendly, along with providing huge energy savings and provide flexibility for your design, but, above all our LEDs are controllable! See our full LED Light Interior Range |
| Using Armadillo's Street Lighting can save operational charges of more than 75%. Dimmable technology also adds to the savings, to enable lighting scenes to be set throughout the hours of darkness for increased savings. Four Lens types have been developed to provide focus of light for Motorways, Gantry Signs, Streets, Pathways, Tunnels, Car parks, Martialling yards, Vehicle Inspection areas and every where a high quality of external daylight is required. See our full LED Street Lighting Range |
| Quality Assurance |
| ArmadilloLED are committed to provide educational information so you can cut through competitive manufacturer claims and separate fact from fiction. We want to help you find products that meet your expectations. We’d be happy to discuss your Lighting requirements and offer guidance for you to make fair comparisons on LED. |
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| 1. Performance Delivery at Application Level 2. Ask for certified Photometric Data 3. Establish Lumen depreciation 4. Look at Light loss Factors 5. Evaluate Lifetime Luminaire ROI |
| Total Solution Approach |
As you begin investigating LED lighting for your specific applications, keep in mind that you're buying an integrated system, not just individual components. An effective LED lighting fixture is only as strong as its weakest link. Look for features that provide the key benefits you expect on every installation – performance, longevity, efficiency, style and reliability. |
| Not all LED luminaires are created equal |
ArmadilloLED understand and add value for providing educational information so you can cut through competitive manufacturer claims and separate fact from fiction. Armadillo use tools for light modelling that all can understand by using freely available Dialux software tools to guide you in making informed buying decisions. Plus, our application engineers and product representatives are well-trained and will help you objectively consider your options. |
Use Measurable Performance DataSpec Sheets and IES Photometric files Case study installations Product Data Sheets ISO Certification WEEE Lifetime Recycling programmes CE CertificaitonRoHS Compliance BS EN Standard Compliance |
| 1. Performance Delivery at Application Level |
| Do not be lead by data only. Many claimed manufacturers supply data from other lighting components and one time lab results. Conduct "in field" application level performance evaluations using IESNA recommended practices and standards. Utilise available design software and application engineering practices to predict application level performance. Evaluate relevant and credible case studies. (case studies link) |
| 2. Ask for Certified Photometric Data |
| Make sure the LED luminaire manufacturer provides a certified photometric report (per IESNA LM-79) from an approved DOE lab to validate the manufacturer's photometric performance claims. |
| 3. Establish Lumen Depreciation |
| Obtain lumen depreciation (life) data for the LED luminaire supported by the LED chip manufacturer's IESNA LM-80 test data, directly correlated to luminaire level performance. Along with thermal characteristics to maintain light levels. |
| 4. Look at Light Loss Factors |
| When a light fixture is activated, it produces light which must leave the lamp, then the fixture, then reach the work plane where it is needed. Along the way, a number of operating and environmental conditions interfere with the transmission of light, resulted in wasted lumens. |
| As an example, a typical outdoor dusk-to-dawn application may be evaluated at a 50,000 hour (11 – 12 year) application life. Based on this example, you would conduct an evaluation based on each manufacturer's 50,000 hour lumen depreciation values. See Benefits of LED (link) |
| 5. Evaluate Lifetime Luminaire ROI |
| Analyse initial investment versus lifetime value by considering all LED fixture benefits such as lighting performance, total power consumption, maintenance and warranty. The entire luminaire must be built to last for the length of the application life. |
| CQS - Colour Quality Scale |
| The purpose of this article is to solicit comments from the solid state lighting (SSL) industry onthe Colour Quality Scale (CQS) developed by National Institute of Standards and Technology (NIST). The CQS is being discussed as one of the proposals in the International Commission on Illumination (CIE) Technical Committee (TC) 1-69 and final discussions are in progress in the TC toward selecting a new metric. Since the SSL industry is not well represented in the TC, we hope to convey the opinions of the SSL industry to the committee members. The colour quality of SSL products is critical and is the subject of increasing attention. The CIE Colour Rendering Index (CRI)[1] has been widely used for many years. However, the CRI is 40 years old and various problems with the CRI when used for light-emitting diode (LED) sources have been identified, as reported in many publications [2-7]. In particular, the report from CIE Technical Committee TC 1-62 "Colour rendering of white LED light sources" [8] summarizes several problems of the CRI when applied to white LED sources. The CRI score does not correlate well with visual evaluation in many cases. In response to the conclusions of TC 1-62, a technical committee TC 1-69 (Colour rendition by white light sources, Chair: W. Davis) was established in 2006 to develop and recommend a new CIE metric. The new metric is intended to eventually replace the CRI (not immediately after publication of the new standard). It should work well for both traditional lighting technologies and SSL sources. At NIST, we have developed the CQS [9-11], which addresses the problems of the CRI for SSL sources yet maintains good consistency of scores with the CRI for traditional sources, and proposed it to TC 1-69. Our spreadsheet to calculate CQS has been distributed to many users in the SSL industry and continues to gain support in the USA. However, the CQS is currently not gaining good support in the TC. The TC is inclined to adopt a different metric, which is a pure fidelity metric very similar to CRI. The traditional lamp industry also has concerns that the concept underlying the CQS deviates from the CRI. We are concerned that another pure fidelity metric will not solve the problems for SSL sources, and we believe that a new concept metric, such as the CQS is needed for the SSL industry. |
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| Fixing the problems of the CRI is critical for the SSL industry |
| Traditional lamp companies have known about the problems of CRI for a long time and have found ways to work around these problems. The SSL industry is different. It is young and consists of numerous small companies. These companies often do not have expert knowledge on colour rendering and colorimetry. They tend to design products that simply maximize the lumens per watt and the score of the colour rendering metric. As products are optimized for the metrics, standards are important. For those who would like to review the issues, we explain below the problems of CRI and how CQS works to solve the problems. We'd appreciate it if you could write to us your comments on the CQS and any experiences you have with CRI and/or CQS for SSL products. Please contact bart@armark.com. |
Colour fidelity is only one aspect of colour quality |
| The CRI assesses the fidelity of colour rendition (colour fidelity) by calculating the colour differences of a set of pre-defined test samples under illumination by a test source and a reference illuminant. It has long been known that colour fidelity cannot serve as a sole indicator of colour quality of white light. There are other aspects of colour quality; in particular, object colour shifts that increase colour saturation can enhance visual preferences, colour discrimination ability, and visual clarity [12-15], improving the subjective rating of colour appearance of the illuminated objects. It is also known that perceived colour saturation of objects is reduced at lower illuminance levels (Hunt Effect). Therefore, it seems that sources that enhance colour slightly in indoor lighting may achieve higher colour fidelity to real daylight [16]. There have been attempts to account for these effects by various proposed metrics such as the Flattery Index [12], the Colour Preference Index [13], the Colour Discrimination Index [14], the Feeling of Contrast Index [15], the Colour Rendering Capacity [17], and the Gamut Area Index [5]. None of them, however, has been accepted as a standard, probably due to the fact that CRI has been so widely used (regardless of the problems) and that the industry refuses to use more than one metric to rate colour rendering of products. The CQS is basically a fidelity metric, producing one number like Ra, but the CQS has improvements including the ability to account for the direction of object colour shifts. The CQS thus agrees well with visual ratings for colour-enhancing sources, while it works as an accurate fidelity metric for non-colour-enhancing sources. The CQS score works to represent the overall colour quality of products (perceptual colour fidelity) for all types of light sources. |
A good CRI score does not guarantee good colour quality |
| One problem with the CRI is that it can give fairly high scores to sources that render some saturated object colours very poorly. An example below shows a case of a red-green-blue (RGB) white LED simulation optimized for highest luminous efficacy of radiation (LER, lm/W) at CRI Ra=80. This light would qualify for Energy Star and achieve high luminous efficacy, but the actual colour rendering is very poor. With R9 = -114, skin tones under this light look pale and unhealthy. The CQS lowers the score of this lamp by seven points from CRI, making it ineligible for Energy Star (LED luminaires). The other leading proposal within the CIE TC, CRI-CAM02UCS, gives this light a score of 81, one point higher than the CRI. Read more in report Development of a Color Quality Scale by Wendy Davis and Yoshi Ohno - National Institute of Standards and Technology |
References
Rationale of Color Quality Scale Yoshi Ohno and Wendy Davis, NIST June 8, 2010 [1] CIE 13.3:1995, "Method of measuring and specifying colour rendering properties of light sources," (1995). [2] N. Narendran and L. Deng, "Color rendering properties of LED sources," Proc. SPIE, vol. 4776, pp. 61–67, 2002. [3] P. Bodrogi, P. Csuti, P. Horv´ath, and J. Schanda, "Why does the CIE color rendering index fail for white RGB LED light sources?," in Proc. CIE Expert Symp. LED Light Sources: Phys. Meas. Visual Photobiol. Assess., 2004, pp. 24–27 [4] Y. Ohno, "Spectral design considerations for white LED color rendering," Opt. Eng., vol. 44, no. 11, pp. 111302-1–111302-9, Nov. 2005. [5] M. S. Rea and J. P. Freyssinier-Nova, "Color rendering: A tale of two metrics," Color Res. Appl., vol. 33, no. 3, pp. 192–202, Jun. 2008. [6] A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevicius, P. Vitta, M. Shur, Statistical Approach to Color Quality of Solid-State Lamps, IEEE Journal of Selected Topics in Quantum Electronics, Vol. 15. No. 6, 2009. [7] W. Davis and Y. Ohno, "Approaches to color rendering measurement," J. Modern Optics, Vol. 56, No. 13, 1412-1419 (2009). [8] CIE 177:2007, "Colour rendering of white LED sources, 2007. [9] W. Davis and Y. Ohno, "Toward and improved color rendering metrics," Proc. SPIE, vol. 5941, pp. 59411G-1–59411G-8, 2005. [10] Davis, W. and Ohno, Y., "Development of a Color Quality Scale (CQS)," Sixth International Lighting Research Symposium on Light and Color, Orlando, FL (2006). [11] W. Davis and Y. Ohno, "The Color Quality Scale", Optical Engineering, 49(3):033602_(2010). [12] D. B. Judd, "A flattery index for artificial illuminants," Illum. Eng., vol. 62, pp. 593–598, Oct. 1967. [13] W. A. Thornton, "A validation of the color-preference index," J. Illum. Eng. Soc., vol. 4, pp. 48–52, Oct. 1974. [14] W. A. Thornton, "Color-discrimination index," J. Opt. Soc. Amer., vol. 62, no. 2, pp. 191–194, Feb. 1972. [15] K. Hashimoto and Y. Nayatani, "Visual clarity and feeling of contrast," Color Res. Appl., vol. 19, no. 3, pp. 171–185, Jun. 1994. [16] Davis, W. & Ohno, Y., "Studies on the effect of illuminance on color rendering," Proc. CIE 2009: Light and Lighting Conference, Budapest, Hungary (2009). [17] H. Xu, "Color-rendering capacity of illumination," J. Opt. Soc. Amer., vol. 73, no. 12, pp. 1709–1713, Dec. 1983. [18] Miller, C.C., Ohno, Y., Davis, W., Zong, Y., and Dowling, K., "NIST spectrally tunable lighting facility for lighting vision science experiments," CIE peer-reviewed Paper publication from CIE 2009 Light and Lighting Conference, Budapest, 2009. [19] Y. Ohno and W. Davis, "Visual Evaluation Experiment on Chroma Enhancement Effects in Color Rendering of Light Source", submitted to CR&A (being reviewed). [20] Report by Japanese national committee of TC1-69, submitted to the TC on Jan. 15, 2010. Also, private communication from Philips in USA. [21] CIE135/2:1999, Colour rendering, TC 1-33 closing remarks, CIE Collection in vision and colour and in physical measurement of light and radiation (1999). |
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