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:

  1. Electrolier counts are approximate which conforms to existing situation in the city at present.
  2. Energy rates are based on Public Utilities Commission approved rates for streetlights, effective October 11, 1979.
  3. 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.
  4. Maintenance charges have been approximated for "batch replacement" of lamps and incidental repairs.

 

Tom Sarkar

Senior Electrical Engineer

January, 1980