ED Lighting Case Study – Lisbon, Portugal

Street Lights 01

Tagus River Bridge

Street Lights 02

Tagus River Bridge


(Lisbon, Portugal) Tagus River Bridge is the longest bridge in Portugal, and it is a very important bond to link the both banks of Tagus River in Lisbon. Everyday tens of thousand vehicles and pedestrians go through the bridge. When considering lighting for the bridge, the city officials decided to utilize a new type of lighting which should be energy efficient with long lifetime instead of HPS street lighting since lighting for the bridge consumes a huge amount of electricity if HPS street lighting is adopted, meanwhile the maintenance costs will also be high. Then which type of lighting has these features? LED street lighting became their best choice, which does not only save electricity, but also has a long lifetime of over 50,000 hours.


As the city officials considered possible LED lighting options to be utilized, they developed a set of requirements for any potential solution. They wanted a solution that would meet or exceed the light output and light quality of conventional street lighting and they wanted a solution that could be easily installed and does not need frequent maintenance.


Trial Installation

They chose several brands of LED street lighting as candidates. A set of selected products were installed in working fixtures on the bridge, and the government collected opinions and rankings from citizens. They also measured light levels for each installation.


The local electricity supplier calculated energy use and savings for the various options being tested. Based on these calculations and the inputs from the various stakeholders, the FOBSUN FSL-56-H LED Street light was chosen as the final solution.



The supermarket installed around 150 FOBSUN FSL-56-H LED Street lights on both sides of the bridge as shown in the table below. The table also shows the hours of operation for each installation.



HPS street lighting wattage






Business Case Analysis

The government conducted an analysis to determine the economic feasibility of adopting FOBSUN LED lighting. This analysis considered several factors including,


*Energy savings

*Capital cost

*Maintenance savings

*Reduction of hazardous materials


Energy Savings

Energy savings was the original driver for this project, and the savings were expected to be significant using the latest LED lighting technology. Each of the FOBSUN FSL-56-H LED Street lights consumes 56 watts. Using the hours of operation and fluorescent wattage from the table above, the energy savings are as follows:


HPS street lighting: 43,800kwh/year

FOBSUN FSL-56-H LED Street light: 12,264kwh/year

Savings: 31,536kwh/year


The government pays $0.17/kwh for its electricity yielding an annual savings of $5361.


Capital Cost

The capital cost of the LED street lights for this project was $20,000


Maintenance Savings

The long service life of the FOBSUN FSL-56-H LED Street lights eliminates the maintenance cost associated with changing light bulbs (the replacement bulb cost and the associated labor). The approximate maintenance cost savings is $4,000/year using very conservative estimates for the labor and lamp costs.



Using the estimates above, the calculated time to payback for this project is slightly more than 2.1 years. Using only the energy savings, the time to payback is slightly more than 3.7 years.


Future Plans

The government is very pleased with the light quality and the appearance of the FOBSUN FSL-56-H LED Street lights, which deliver bright white light. The LED Street light is safer for vehicles and pedestrians, meanwhile the CO2 emissions and light pollutions have been greatly reduced. The government has identified additional applications for the product in order to increase its energy savings.


Copyright ©2006-2013 FOBSUN.COM. All Rights Reserved.