Alliance for Lighting Information

Errors in the CEC's Eley Outdoor Lighting Research Report

by David M. Keith

The California Energy Commission (CEC) is developing proposed legislation that will include restrictions on outdoor lighting. The CEC commissioned the Eley Outdoor Lighting Research Report to be the technical basis for its proposed sections on outdoor lighting in the 2005 Energy Efficiency Standards.

The report has a section on parking lots. The following figure is shown in the Eley Report (2002-06-06) as Figure 4 and clearly shows the elements used in the calculations that are the entire basis for the proposed requirements for parking lots for the upcoming state-wide legislation - and how entirely wrong those calculations are.

Figure 4 shows the location of the "minimum illuminance" incorrectly at a point between luminaires instead of in the corner of the lot, where it will certainly occur given the other restrictions for this calculation. The figure also shows that the area used for the denominator of the Lighting Power Density (LPD) calculation includes the entire square within the "border of lighted area" line in the figure. The Eley Report says the recommended values meet the relevant IESNA recommended practice, RP-20-98. However, while the values reported from the erroneous calculations do meet the criteria of RP-20-98, the correct values are not even close. As a result, all of the data in the Eley Outdoor Lighting Research Report about parking lots is wrong, does not refer to designs meeting the referenced standard, and provides no reliable technical basis for the CEC's proposed legislation.

Of course one error may be just a mistake - but in this case it is very hard to let it go with an "oops!" because this report is purchased by public funds from reputedly professional sources with the intent of using it as technical support for state-wide legislation effecting every parking lot in the state of California. If the CEC's Eley Outdoor Lighting Research Report can contain such an obvious error in such a significant part of the text, it seems reasonable to ask what other errors may be included, even if less visible.

An answer to that is found in the section on roadways in the Eley Report. In Table 38, the models used for establishing LPD values for roadways are described, with such examples as LZ3/Expressway-MediumConflict roadway as "6 @15' drive lanes, 2 @ 12' 'breakdown' lanes (outer), 2@8' 'breakdown lanes' (inner), 20' median, 2 @20' grading zone at edges". The discussion says the calculation is based "only on the traveled way square footage for each roadway .. This includes the breakdown lanes and parking lanes on roads, but does not include the median or grading edges." The traveled way defined in the referenced recommended practice (RP-8-00) does not include breakdown lanes or parking lanes - but the calculations here apparently do. So which is it? Since no example calculation is shown, it is impossible to tell if this is a different (and unique) definition or an erroneous calculation. It is impossible to know what area is used to calculate the LPD values either - the travelled way or the "travelled way" that includes "the breakdown lanes and parking lanes on roads" - but the difference is tremendous. At the very least, the language is confusing, and a simple cross-section of a roadway could have shown the basis for the calculations. However if areas that are not lighted to meet RP-8-00 - such as "breakdown lanes or parking lanes" - are included in the denominator of the LPD calculation, then the proposed LPD values are meaningless because the effectively lighted areas in the numerators do not correspond to the areas in the deonominators.

There are many other technical problems in this section on roadways. For example, there is the assignment of roadway and pedestrian conflict classifications in accordance with the LZ value. The results in Table 41 for LZ1 and LZ2 are entirely skewed by this unwarranted assumption. There is no reference or basis for such assignments, that would allow roadways in LZ1 areas to be lighted to only the level of local-low pedestrian conflict (0.036 W/ft2) regardless of the actual roadway type. Within the section, the Lamp Lumen Depreciation value is noted, but the overall Light Loss Factor - a much more important and useful number - is not mentioned. As another example, the program cited (LitePro v1.02) can not do calculations in accordance with the referenced ANSI/IESNA practice RP-8-00, because no veiling luminance calculation is available in that program. There are entries in Table 40 - Roadway Lighting Calculation Results - for Veiling Luminance Max/Avg Ratio, so either another program was used or these results are not part of "the results".

Finally all the recommendations about roadways are in error because they ignore the most basic point of all - that roadway LPD values need to correspond not only to the LZ and roadway classification but to the number of lanes. The IESNA publication Unit Power Density for New Roadway Installations IESNA LEM-6-87 and recent research into roadway Unit Power Density (similar to LPD) published in the Journal of the IESNA [Keith, JIES v29n2, v31n2 and v 32n1] clearly show the fundamental technical relationship between the number of lanes and roadway UPD. However neither these nor any other references are cited. Instead calculations are made using software that does not meet the recommended practice, for roadways that are of undefined width and unrealistic classifications, meeting criteria that seem to be arbitrarily redefined.

As a result, the recommendation in Table 41 is for all roadways in LZ1 to be limited to 0.036W/sqft (about 0.39 W/m2) which according to published research (in the JIES v32n1 p18) is barely enough to light a two lane local-medium roadway and not enough to light any other roadway of any size or classification to meet the current recommended practice (assuming that the definition of travelled way is consistent with RP-8-00). Apparently this energy standard is attempting to overrule the American National Standard Practice for Roadway Lighting, ANSI/IESNA RP-8-00 by re-classifying roadways without citing any other reference, and mandate that for everyone.

Another difficulty with the Eley report is that the use of terminology about rated mean lumens seems - at least - confusing. No definition of mean is specifically provided in the report, but repeated mention is made of "rated lumens: output at 40% of rated lamp life" although this definition is for MH lamps only because the definition of mean for MH is different from the definition of mean for every other light source presently available. All the other sources discussed in the report have mean lumens at 50% of rated life - consistent with the meaning of "mean" - but this is not mentioned even when rated life and mean lumens per Watt are shown for different sources.

There is a recurring problem with criteria. Throughout the report, references are made to using or meeting IESNA criteria, but in places the criteria for the Eley Report calculations were simply made up or not met. In the section on sidewalks, following Table 15 the report says "The results in Table 15 indicate that it is possible to meet the illuminance criteria, but not the uniformity criteria . . ." but then proceeds to propose LPD values based on these calculations that do not meet the criteria set in the report. Therefore from this section on sidewalks, the proposed LPD values are based on a model of lighting that does not meet IESNA criteria.

The same inattention to criteria appears in the roadway section and parking lot section. In the roadway section, the calculation results are shown in Table 40 for a Local - Low Conflict roadway - and this is the only calculation for any roadway in LZ1. However, Table 41 shows LPD values for Expressway, Major, Collector and Local roadways in LZ1 - but they are all the same - the value for the Local roadway. The "n.a." used elsewhere in the same table would be more appropriate, and avoid the implication that the LZ1 LPD values are appropriate for any roadways other than 2 lane local low conflict roadways.

In the parking lot section, the note to Table 7 indicates that the LZ1 parking lot criteria are for "periods of non-use" and not the criteria listed in the referenced standard for parking lots that are actually lighted at night (in any case the use of the erroneous "minimum" values discussed above means the calculated values do not meet the referenced criteria.) This inattention to criteria appears to be a problem throughout the report.

As an additional check, the values for lamps used in the canopy calculations were investigated. Once again the report fails to provide reliable information. Table 29 shows the Lamp Performance Data - Outdoor Canopies information, followed by a statement that "Fifty-five mean lumens per Watt (MLPW) is the recommended source value for calculating allowed LPD" (a criterion that is repeated throughout the report.) Table 29 shows the MLPW values for MH sources to be between 45 and 56, but only one general reference is given for all of the numbers shown in Table 29. From that reference, for 150W MHPS lamps, only two product numbers (47102 and 47615) were found - and both ballasts use 185W (not 180W shown in Table 28), corresponding to MLPW of 54. Values from other lamp manufacturers are lower than those reported here, sufficient to make no MH 100W or 150W source meet the 55 MLPW target. Even so the Eley report cites these values throughout. This is an even more significant error whenever applications use horizontal position lamps (the case for most outdoor area lighting, but not canopies) because the difference between the rated lumens and mean lumens of horizontal and vertical MH lamps is ignored, disregarding the fact that horizontal MH lamps typically provide 90% or less of the output from similar vertical MH lamps. The values in Table 28 for the rated lumens and life of the 100W and 150W MH lamps exceed those listed by other maunfacturers for horizontal MH lamps. Typical MLPW for MH pulse start lamps burning horizontally would be closer to 45. Finally, Table 29 shows two HPS sources (which are speciality versions with reduced mercury content) that have rated life reduced to 20,000 from the HPS typical rated life of over 24,000 hours - so the presentation of HPS lamps seems incomplete at least. In summary, the values and information presented in Table 29 are not reliable in themselves.

From the discussion of the calculation for the canopies, Figure 7 from the report shows the results - only six of the eight pumping locations meet the 20 fc target. The asymmetry of the countours shown is entirely unexplained and, according to the description of the components of the model, should not occur.

From this partial review of the CEC's Eley Outdoor Lighting Research Report there are good reasons to question the information provided about lighting for parking lots, canopies, sidewalks and roadways, that may be offered in support of proposed legislation on outdoor lighting, because it is repeatedly confusing, misleading, incorrect or simply wrong.

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