San Jose: Study and report on low-pressure sodium lighting, 1980

San Jose: Study and report on low-pressure sodium lighting, 1980

City of San Jose

Department of Public Works

San Jose, CA 95110

Below is Section 6 (page 8) from the above report.

6. Cost Comparisons of HPS Vs. LPS systems

The Public Works Department has prepared the following table showing comparable installation, maintenance and operation (running) costs for six possible conversion options. The option recommended by the Public Works Department is the option titled, "Light Combination Suggested by Lick Observatory Staff," with the exception that streetlights within the immediate vicinity of signalized intersections be converted to HPS.

As is shown on the table, the LPS conversion would cost significantly less than the HPS conversion ($845,000 or 20%). Furthermore, total operating costs would be lower for a primarily LPS conversion system, as shown in option #4 (Lowest Energy Cost). Option #6, Light Conversion Suggested by Lick Observatory Staff, is an option suggested as a compromise to the total LPS conversion system that Lick Observatory would prefer. The option represents Lick Observatory's request that no HPS luminaires be installed within a nine-mile radius of the Observatory complex on Mount Hamilton.

INSTALLATION & ENERGY COST FOR STREETLIGHTING

JANUARY, 1980

Conversion	No.	Installation Cost per Unit	Energy Cost per Year/Unit	Total Cost of Installation	Total Energy Cost per Year	Total Maintenance Cost per Year	Total Operating Cost per Year
All Low-Pressure Sodium
1. 175W Merc to 55W LPS	20,000	135.00	14.232	2,700,000	284,640	132,000	416,640
2. 250W Merc to 90W LPS	5,500	180.00	23.412	990,000	128,766	36,300	165,066
3. 400W Merc to 90W LPS	3,500	180.00	23.412	630,000	81,942	23,100	105,042
				4,320,000	495,348	191,400	686,748

All High-Pressure Sodium
1. 175W Merc to 70W HPS	20,000	175.00	14.460	3,500,000	289,000	124,800	414,000
2. 250W Merc to 100W HPS	5,500	185.00	21.012	1,017,500	115,566	34,320	149,886
3. 400W Merc to 150W HPS	3,500	185.00	30.180	647,500	105,630	21,840	127,470
				5,165,000	510,396	180,960	691,356

Residential, Low-Pressure Arterial St., High-Pressure
1. 175W Merc to 55W LPS	20,000	135.00	14.232	2,700,000	284,640	132,000	416,640
2. 250W Merc to 100W HPS	5,500	185.00	21.012	1,017,500	115,566	34,320	149,886
3. 400W Merc to 150W HPS	3,500	185.00	30.180	647,500	105,630	21,840	127,470
				4,365,000	505,836	188,160	693,996

Operating Cost for Existing Mercury Vapor Lights
1. 175W Merc	20,000	--	35.244	--	704,880	72,000	776,880
2. 250W Merc	5,500	--	50.784	--	279,312	19,800	299,112
3. 400W Merc	3,500	--	80.832	--	282,912	12,600	295,512
					1,267,104	104,400	1,371,504

Lowest Energy Cost
1. 175W Merc to 55W LPS	20,000	135.00	14.232	2,700,000	284,640	132,000	416,640
2. 250W Merc to 100W HPS	5,500	185.00	21.012	1,017,500	115,566	34,320	149,886
3. 400W Merc to 90W LPS	3,500	180.00	23.412	630,000	81,942	23,100	105,042
				4,347,500	482,148	189,420	671,568

All Low-Pressure within 9 Miles of Lick Observatory LPS-HPS Combination for Other
1. 175W Merc to 55W LPS	20,000	135.00	14.232	2,700,000	284,640	132,000	416,640
2. 250W Merc to 90W LPS	1,210	180.00	23.412	217,800	28,329	7,986	36,315
3. 250W Merc to 100W HPS	4,290	185.00	21.012	793,650	90,141	26,770	116,911
4. 400W Merc to 150W HPS	3,500	185.00	30.180	647,500	105,630	21,840	127,470
				4,358,950	508,740	188,596	697,336

Light Combination Suggested by Lick Observatory Staff
1. 175W Merc to 55W LPS	20,000	135.00	14.232	2,700,000	284,640	132,000	416,640
2. 250W Merc to 90W LPS	1,210	180.00	23.412	217,800	28,329	7,986	36,315
3. 250W Merc to 100W HPS	4,290	185.00	21.012	793,650	90,141	26,770	116,911
4. 400W Merc to 90W LPS	3,500	180.00	23.412	630,000	81,942	23,100	105,042
				4,341,450	485,052	189,856	674,908

NOTE:

Electrolier counts are approximate which conforms to existing situation in the city at present.
Energy rates are based on Public Utilities Commission approved rates for streetlights, effective October 11, 1979.
Estimates for "Cost of Installation" have been derived from contractor's bid for conversion of 2,000 streetlights, adjusted for the cost of present interest rates for installment payment and escalated 15% for inflation for one year.
Maintenance charges have been approximated for "batch replacement" of lamps and incidental repairs.

Tom Sarkar

Senior Electrical Engineer

January, 1980