Alliance for Lighting Information

Table of Contents

What's New
Technical terms
About ALI

What's New

Circadian Stimulus and S/P Ratios
discusses the directly proportional relationship between a light source's S/P ratio - used widely now in marketing - and its corresponding stimulus to the human circadian system.
Some Inconvenient Truths About CFLs
include the lack of energy savings from "normal power factor" CFLs, the difference in life and savings from frequent switching, and disposal issues.


is a complex and important issue in outdoor lighting, and some topics are discussed here along with links to more information.
are involved in outdoor lighting design and maintenance decisions. This page introduces the issues and provides links to more information within the ALI website.
Environmental Effects
from outdoor lighting are evident and hidden. This page presents some of the signfiicant issues and links to more information in the ALI website.
Health Effects
from lighting are varied - from sunburn to neurotoxin pollution - and in particular, recent research is showing that light can have a very significant health effect on melatonin and our diurnal cycle.
Legislation and Ordinances
are being proposed and adopted in many areas, from local jurisdictions up to states (so far). This page cites some of the issues and provides links to information with the ALI website that may be relevant to lighting legislation and ordinances.
Light Pollution or Skyglow
is a growing concern and to some extent depends on choices made when lighting systems are designed. This page introduces the issues and provides links to more information within the ALI website.
Older Eyes
work differently under outdoor lighting levels and conditions, particularly driving at night. This page provides brief information about the most important effects of aging on vision, and includes links to more information within the ALI website.
back to the top

Technical terms

Efficacy of Metal Halide and High Pressure Sodium Sources
End-of-Life Lamp Lumen Data
Foveal, Para-foveal and Peripheral Vision
Initial and Maintained Conditions
Lamp Lumen Depreciation (LLD)
Light Loss Factor (LLF)
Luminaire Cutoff Classification by the IESNA Roadway Lighting Committee
"Mean" for Metal Halide and High Pressure Sodium Sources
Photopic Sensitivity Functions
Rated Life of Metal Halide and High Pressure Sodium Sources
Rated Lumens and Initial Efficacy
Rated Lumens for Various Outdoor Sources
Rayleigh Scatter Index (RSI)
Relating Intensity and Flux using Solid Angle and Zonal Multipliers
RSI Data for Sources
Retinal Ganglion Cells and Melanopsin
Scotopic Sensitivity Function
Uniformity Ratio
Unit Power Density (UPD)
Unit Uplight Density (UUD)
back to the top


Color Contrast
discusses how contrast has both luminous and chromatic aspects, and what that means about contrast calculation methods and results.
Color Rendering Index Values for MH
discusses the "chromatic difference" metric DC in the CIE's Colour Rendering Index calculation (CIE 13.3-1995) and why CRI values for MH sources are at best "less accurate".
Errors in the Eley Outdoor Lighting Research Report
includes information about problems in the document used as the sole technical basis for the outdoor lighting portion of the CEC's proposed legislation.
A Misleading Example of Outdoor Lighting
discusses the use of the Ferrari of Denver auto dealership as an example of quality outdoor retail lighting - even though it fails to meet the IESNA requirements (in RP-20-98) for parking lot lighting!
Melanopsin, Melatonin and Human Health
presents recently developed information on the relationship between retinal ganglion cells and melanopsin, melatonin and effects on human health.
Mesopic Vision and Outdoor Lighting Criteria
discusses the mesopic range and the luminances that correspond to outdoor lighting design criteria.
PIER Review
by Jefferey Knox discusses his findings in a review of the Public Interest Energy Research (PIER) program's Outdoor Lighting Baseline Assessment Final Report on behalf of the California Energy Commission. Additional discussions on specific issues include:
Recurring Errors in Ordinances: Site Uniformity and Property Line Limitations
discusses the problems that misunderstood and misapplied elements in ordinances can produce.
Roadway Lighting Research
discusses the findings from research into Unit Power Density (UPD) and Unit Uplight Density (UUD), published in four papers by David Keith in the Journal of the IESNA from 2000 through 2003.
Some Inconvenient Truths About CFLs
include the lack of energy savings from "normal power factor" CFLs, the difference in life and savings from frequent switching, and disposal issues.
There is More to Lighting Quality Than What Meets the Eye
presents the issues involved in outdoor lighting quality, recognizing that the visual appearance and performance of a lighting system are only part of the complete story.
Uniformity Ratios in Ordinances
discusses the way such ratios are defined and implemented in lighting ordiances, along with problems that occur when the implications of uniformity ratios are not undestood.
What Blue Skies Tell Us About Light Pollution
is a introduction to the issues of skyglow and particularly evaluation of relative contributions by different light sources.
Why MH Systems Cost More Than HPS Systems
discusses the relative costs - in monetary and environmental terms - of choosing Metal Halide or High Pressure Sodium sources for outdoor lighting.
Xenon Headlights
are a nuisance (or worse!) for many drivers and this discussion includes review of the relevant standards and reasons why these headlights are such a pain in the eye.
back to the top


Legislation, Ordinances and Energy Codes: the Future for Outdoor Lighting
- an outline of the the presentation made to the IEEE 2003 Regional Conference in Denver, CO in March. The Powerpoint presentation (255 kB) is available here.
IESNA Street and Area Lighting Committee 2001
conference included this Powerpoint presentation about research into Unit Power Density (UPD), with special emphasis on the potential reduction of uplight.
Sources, Surfaces and Eyes: Calculational Procedures Incorporating Spectral Distribution Information
is the Powerpoint presentation (pdf format, 1.6 MB) made in August 2003 at the IESNA Annual Conference.
Sources and Surfaces: Evaluating Spectral Distribution Interactions Using Roadway Signage
is a 2004 presentation to the IES Roadway Lighting Committee on the results of using spectrally informed calculation procedures to evaluate the contrast of roadway signage surfaces under diffferent sources (pdf format, 0.3 MB). The corresponding paper is available here (in .pdf format, 59 kB).
Sources, Surfaces and Scatter
is the Powerpoint presentation made to the International Dark-sky Association 2003 Annual Conference in Tuscon, AZ in March The abstract is available here.
The Spectra of Choices in the Choice of Spectrum
is the Powerpoint presentation (pdf format, 2.7 MB) made to the 2004 IESNA Street and Area Lighting Conference. Links to additional information about the topics discussed in the presentation are here.
back to the top


Roadway Unit Uplight Density (UUD) Calculation Examples
includes information about calculating UUD with references and examples.
Scientific Method in Research
is the topic of this paper by Professor Gifford, part of a discussion on Full Spectrum Lighting.
Sources' Spectra, Roadway Surfaces and the Potential for Uplight Scattering
is the paper submitted to the International Dark-sky Association 2003 Annual Conference in Tuscon, AZ in March. The abstract is here.
Technical Summary of Research into UPD and UUD
is (the browser version of) a discussion of the work, results and conclusions published in four papers by David Keith in the Journal of the IESNA since 2000 (and the document in pdf format is here.)
back to the top


2005 Update Residential & Nonresidential Energy Efficiency Building Standards
has been developed by the California Energy Commission, based on the Eley Outdoor Lighting Report and the PIER Outdoor Lighting Baseline Assessment. Proposed measures are outlined in this presentation.
Colorado Jurisdictions
which have been posting lighting standards or ordinances on the web are linked to the IESNA's Rocky Mountain Section's website.
Full Spectrum Lighting
is discussed in this website, including Professor Gifford's paper on scientific method.
Lance Hahn's Retina Reference
is an excellent discussion about the retina and eye - detailed, technical and comprehensive - based in part on the highly recommended book "Color Science" by Wyszecki & Stiles.
Links about Color
are available on the ALI Color page.
Additional ALI links can be found here
and corrections or contributions are welcome, please send to David Keith
back to the top

For more information, or to send along comments, suggestions or contributions, please contact David Keith by email at

This site is provided as a service by resodance publishing co. and no guarantee is implied or provided. For more information, contact resodance publishing co.

This page is served & maintained by &
last changed on 1 Jun '12 by

free hit counters
free hit counters