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Home My WebLink About1979-12-04; City Council; 6091; Conversion Street Lights Mercury to Sodium Lamps^DEPARTMENT: • CITY OF CARLSBAD AGENDA BILL NO. _ DATE: _ '-___ _ ^December 1979 Engineering Initial: Dept. Head C. Atty C. Mgr. SUBJECT:CONVERSION .OF STREET LIGHTS FROM MERCURY VAPOR LAMPS TO HIGH PRE-SSURE SODIUM LAMPS STATEMENT OF THE MATTER The rising concern fo a revision of City po r-ent City policy call acteristic bluish whi .to require.the use of 1: i gh t . The h i gh p'res energy efficient at p It' is al so1'suggests d. ; examine the possibi 1 i lights to 'high pressu session. -/The cost fo lights would be in th current electric rate pendent upon whether Taking into considera replacement costs, th ,,a)p p roximately six to the Sa n Diego.Gas & El a,T 1 of their street 1 h'.igh pressure sodium early as next January r energy conservation has brought about the need for licy and practice on street light installations. Cur- s for the use of mercury vapor lamps with their char- te light.- 'Staff feels this policy should be changed h\ gr\: pressure sodium lamps with their golden orange, sure sodium lamps are si ightly more than twice as reducing, light than the existing mercury vapor lamps, by staff that the City Council direct.the sta f.,f • to ty of converting all of the City's existing street re. sod i urn lights for submission at the next budget r converting the approximately 1,200 City-owned street e neighborhood -of $210,000. The annual savings at s would be somewhere between $k5,500 and $25,000 de- existing lighting 1. e v'-e Is are reduced or in cr eased . tion all the various expenses involved, including lamp e City could expect a payback on its capital outlay in seven years. As a final comment, it should be noted that ectric Company is presently working on a plan to convert ights (of which 650 lie within the City of Carlsbad) to lamps within the next three years beginning perhaps as EXHIBITS ' ' Memorandum to City Engineer dated November 13, 1979- RECOMMENDATI ON As a visible means of demonstrating to the community the City's desire to conserve energy and as a means of saving the taxpayers' money, staff makes the following recommendations: 1. That the City institute a new policy requiring the installation of high pressure sodium lamps at all new street light insta 1 1 ations un1ess an alternate type is specifically approved by the City Engineer; and That the City institute a plan for the conversion of all City-owm streetlights to high pressure sodium lamps within a time, frame as determined by the City Counc i 1 arid ' wi thi n exist i ng budc ty-owned rat ng budgetary constraints. C o u n c ii 1 Action: 12-4-79 Council approved staff recommendation as set forth above. MEMORANDUM TO: City Engineer FROM: Engineering Design DATE: November 13, 1979 SUBJECT: CONVERSION OF EXISTING STREET LIGHTS FROM MERCURY VAPOR LAMPS TO HIGH PRESSURE SODIUM LAMPS High pressure sodium (HPS) lamps can be distinguished from mercury vapor lamps by the distinctive golden orange light they produce as compared to the bluish white light of the mercury vapor lamps. HPS lamps have one great advantage over mercury vapor lamps in that they are twice as energy efficient as the latter. HPS lamps produce about 100 lumens per watt while mercury vapor lamps produce only 50 lumens per watt. The lumen is a standard unit for measuring light output. Mercury vapor lamps are generally available in 7,000, 10,000 and 20,000 lumens while HPS lamps are available in 5,800, 9,500, 16,000 and 30,000 lumens. Due to these differences in luminosity ratings, the energy savings will be dependent on which particular luminosity rating is used. On newly in- stalled street lights, the energy use can be cut in half as the distance between street lights can be adjusted to compensate for the higher or lower street light luminosities. However, the conversion of existing street lights presents a more complicated problem'. It will have to be decided whether the lighting should be increased or decreased over the present lighting levels. It is our recommendation that the City pursue a policy of decreased lighting to increase the energy savings and en- hance the nighttime visual effect of the City. This is the approach taken by the City of Los Angeles in their attempt to reduce the energy consumption of their street lights by 25% as reported in the Law Enforce- ment Assistance Administration Emergency Energy Committee Energy Report No. 2, titled Street Lighting, Energy Conservation and Crime, dated March 1, 197^- The report did recommend that discretion was advised and,that police officials and area residents be consulted prior to mak- ing any reduction in street lighting levels within a given area. There are two primary disadvantages in the use of HPS street lights. The first is the relatively shorter life span of the HPS lamp. The manu- facturers' recommended replacement life for a.HPS lamp is 20,000 hours versus 24,000 hours for mercury vapor/lamps. :Assuming an average use of 12 hours per day, this translates into a replacement life of approxi- mately 4.5 years versus 5-5 years respectively. The relative economic importance of this will be considered later in this report. The second disadvantage of HPS street lights occurs with the citizens' initial ob- jection to the lights' .characteristic golden orange coloring. It should be noted that this objection is generally short-lived. Test results as reported in the Journal of Illuminating Engineering Society, October, 1975 issue, indicate that HPS lamps produce significantly better visi- biJity than mercury vapor lamps and that customers familiar with both lamp types have a marked preference for the HPS lamp. -2- In the event the City Council considers the possibility of converting existing street lights to HPS lights, the following economic analysis should be helpful. According to an article presented in the Amer ican Public Works Association Reporter, August, 1979, a municipality with at least 200 units to change could have a completely new luminaire, ballast and lamp installed on an existing pole for about $175 to $225 including labor. Costs could be reduced somewhat if it is found that the City's existing 1uminaires are compatible with HPS lamps and""if unit quantities were greater. For the purpose of this study we have used the lower figure since the City owns approximately 1,200 street lights and we have added an additional $20 per street light to account for,the reduced life expectancy of the HPS lamps. This brings the total capital cost per street light to $195 for the purpose of economic analy- sis. Assuming an average energy savings of $30 per year, based on the current SDGSE rate schedule for customer-owned street lights, the pay- back on the City's capital costs, including future lamp replacement costs, will be approximately 6.5 years. In the event that energy rates increase in the future (and they almost certainly will.), the payback time could be significantly shortened. To put this analysis in a different perspective, if all City-owned street lights were converted to HPS lamps and the lighting level was reduced, the energy savings to the City at the present rates would be approximately $45,500 per year. Assuming lighting levels were not re- duced but increased or at least maintained, the City would still save approximately $25,000 a year in energy costs. The total cost of con- verting all City lights would be approximately $210,000. An additional benefit of a City program for the conversion of City street lights to HPS lamps would be as a visible means of demonstrating to the community the City's desire to conserve energy and save the tax- payers' money. For these reasons the Engineering Design Section makes the following recommendations. 1. The City should institute a new policy requiring the installation of HPS lamps on all new street light installations. 2. The City should, within budgetary constraints and on a time frame determined by the Council, embark on a street light conversion pro- gram to convert all existing mercury vapor street light lamps to HPS lamps. As a final comment, it should be noted that from our conversations with Mike Leite of SDG&E it appears they are presently working on a plan for the conversion of all of their utility-owned lights within the next three years. SDG&E has not yet received the approval of the Public Utilities Commission nor have they worked out all the financial details; however, they were somewhat optimistic that they would begin their program as early as next January. DAH:VEB