Industrial Utility Efficiency

Seven Sustainability Projects: Lighting Optimization

Seven Key Sustainability Projects

1. Metering 5. Lighting
2. Demand Control 6. Heat Recovery
3. HVAC Optimization 7. Project Implementation
4. Compressed Air


Reducing energy costs and pollution emissions involves many areas within an industrial facility. My studies have found 7 key (or common) areas where low cost practical projects can be implemented. Combined, these projects provide savings exceeding 10% of the annual energy spend of a typical industrial facility - with an average payback of less than one year.

This month’s article will focus on Lighting. Optimizing the lighting system can help reduce annual energy costs by approximately 2%. Lighting is a popular energy saving project and many facilities have already begun projects in this area. Often some key points are overlooked resulting in project costs being higher than necessary. Understanding the correct requirements can significantly reduce capital costs.

Lighting Energy Costs and Project Objectives

The factory used for this example is a facility with 149,000 sq. ft. including manufacturing floor, warehouse, and office areas. The factory produces small metal and plastic injection-molded components. The annual energy spend for the facility is \$1,483,000. There are 125 Metal Halide light fixtures and 355 fluorescent light fixtures. Lighting energy costs are 4.5% of the total energy spend or \$67,200 per year. The objective of a lighting optimization project is to:

Reduce energy usage of the lighting systems by providing the correct amount of light at the correct time with efficient fixtures.

Symptoms which can help identify the need for a lighting project include:

  • Light levels are higher than necessary for the type of work being accomplished.
  • Light fixtures are at a greater distance than necessary from the work area or in improper position.
  • Excess lights are operating in areas without people working under the lights.
  • The current light fixtures are not high efficiency.


  #1 400 watt metal halide light fixtures.    
  #2 These 6 bulb T-8 Fluorescent fixtures use 50% less energy    

Step #1: Understand Current Lighting Status

  #3 Lights near windows are wasting energy.    
  #4 Often light fixtures are obstructed.    

If minimizing capital expenditure is important, then the sequential steps of a lighting project need to be followed. The first step is to understand your current lighting status. This would include a survey of the major facility areas such as the manufacturing floor and warehouses. The survey should include the following:

  • Number of fixtures
  • Bulb type and watts per bulb (example: 400 watt MH or 96 watt T12x4 ft fluorescent)
  • Number of bulbs per fixture
  • Hours per week the fixture is on without someone working under the fixture. (reference photos #5 and #9)
  • Is it possible to move the fixture closer to the work areas such as lowering it down or aligning it so the light is not blocked by an obstruction? (reference photo #4 and #8)
  • Is ambient light available from windows or skylights which may allow the light fixture to be off during sunlight hours? (reference photos #6 and #7)
  • Is the light level reduced in non-precision work areas such as walk-ways and storage when compared to work-station areas?


  #5 Lights on without workers and excessive lighting in non-work areas.    

Step #2: Determine Existing Energy Costs

The second step is to determine the value of changing the status of the existing light fixtures. For this example, I will consider the 440 watt Metal Halide light fixtures which are commonly used in many industrial facilities. The current energy cost of the 125 Metal Halide light fixtures is \$46,563 per year.


# of Fixtures X watts per fixture/1,000 X hours on per week X weeks per year X \$/kwh = \$/year

125 X 440 watts/1,000 X 166 hours/week X 50 weeks per year X \$0.102/kwh = \$46,563 /year

Step #3: Determine the Correct Amount of Light:

There were sixty (60) fixtures which could be moved closer to the work area. By moving them closer, we were able to eliminate twenty (20) fixtures resulting in a energy savings of \$7,450.

  #6 A simple light sensor can shut down lights when the sun is shining.    


# of Fixtures X watts per fixture/1,000 X hours on per week X weeks per year X \$/kwh = \$/year

20 X 440 watts/1,000 X 166 hrs/week X 50 weeks per yr X \$0.102/kwh = \$7,450 /year

Step #4: Use Lighting Only When Needed:

Turning off the lights when a person is not working under the lights is another opportunity. Using occupancy sensors, we found thirty (30) lights in storage areas and warehouse aisles that could be turned off an additional eighty (80) hours per week. The savings was \$5,385.

  #7 These lights are turned off by sensors when the sunlight is available.    


# of Fixtures X watts per fixture/1,000 X hours on per week X weeks per year X \$/kwh = \$/year

30 X 440 watts/1,000 X 80 hours/week X 50 weeks per year X \$0.102/kwh = \$5,385 /year

Step #5: Use Energy-Efficient Fixtures:

Upgrading the lights to high-efficiency light fixtures will reduce the energy use per fixture by 50% and use 220 watts per fixture vs the original 440 watt. Remember we eliminated 20 lights and reduced the hours of 30 more lights. (Reference photos #1 and #2)

  #8 Lowering the lights from the ceiling reduces energy waste.    


# of Fixtures X watts per fixture/1,000 X hours on per week X weeks per year X \$/kwh = \$/year

75 X 220 watts/1,000 X 166 hours/week X 50 weeks per year X \$0.102/kwh = \$13,969 /year

30 X 220 watts/1,000 X 86 hours/week X 50 weeks per year X \$0.102/kwh = \$2,895 /year

Total savings for high efficiency = \$16,846/year

Step #6: Calculate total Energy Savings and ROI

The total energy savings per year is \$29,681. This is the sum of upgrading lights to high efficency fixtures ($16,846 savings), using lights only when needed ($5,385), and providing the correct amount of light ($7,450).

The costs involved with generating these savings include:

  1. Materials: the light fixture used to replace the 440 watt metal halide fixture is a T8 6 lamp fluorescent fixture, 32 watts per bulb. The cost is \$205.00 USD including the motion sensor, the electrical cord and plug, hangars, and safety chain. Calculation: 105 new fixtures x \$205.00 = \$21,525 for the cost of the project.
  2. Labor: In house labor was used to install the fixtures-no cost.


  #9 An occupancy sensor can help determine the amount of time lights are on without people in the area.    

In this lighting optimization project, annual energy savings were \$29,681 with project costs of \$21,525. The simple ROI on the project is 8.7 months.

Audits and Surveys

Lighting vendors are often willing to help perform your lighting surveys and provide recommendations for a higher efficiency lighting scheme. Be sure to ask them to consider occupancy rates and light intensity levels for different areas. If you receive a quotation for new fixtures I recommend that you request to have the quotation written with line item cost for each type of fixture and sets of fixtures including the current energy usage, proposed energy usage and savings for each. Review the quotation and identify the fixtures which do not have a good payback and eliminate them from the project. Often this process of elimination will help you to reduce the overall project cost and result in an excellent ROI.


Reduce energy usage of the lighting systems by providing the correct amount of light at the correct time with efficient fixtures.


Thomas Mort is a Senior Auditor with Thomas Mort Consulting.


To read the next six Sustainability Projects from this series please make your selection below:

Heat Recovery

HVAC Optimization

Project Implementation


Air Compressors

Demand Control