List of Energy Saving Opportunities in Lighting Systems

List of Energy Saving Opportunities in Lighting Systems

The share of energy used for lighting in the industry is relatively smaller but the potential for energy conservation in a lighting system is quantitatively high. Lighting is used either to provide overall ambient lighting throughout manufacturing, storage, and office spaces or to provide low-bay and task lighting to specific areas. High-intensity discharge (HID) sources are used for the former, including metal halide, high-pressure sodium, and mercury-vapour lamps. Fluorescent, compact fluorescent, and incandescent lights are typically used for task lighting in offices. Lighting also generates a significant amount of heat. The downstream savings of lighting efficiency measures can therefore include cost savings in facility HVAC operation and energy use. The magnitude of downstream savings depends on climate and weather conditions.

Lighting controls: Lights can be shut off during non-working hours by automatic controls, such as occupancy sensors that turn off lights when a space becomes unoccupied. Occupancy sensors can save up to 10-20% of facility lighting energy use.

Electronic ballasts: A ballast is a mechanism that regulates the amount of electricity required to start a lighting fixture and maintain a steady output of light. Electronic ballasts save 12-30% power over their magnetic predecessors. New electronic ballasts have smooth and silent dimming capabilities, in addition to longer lives (up to 50% longer), faster run-up times, and cooler operation. New electronic ballasts also have automatic switch-off capabilities for faulty or end-of-life lamps. The typical energy savings associated with replacing magnetic ballasts by electronic ballasts are estimated to be roughly 25%; however, the total energy savings will depend on the number of magnetic ballasts still in use.

Replacing T-12 tubes with T-8 tubes: In many industrial facilities, it is common to find T12 lighting tubes in use. T-12 lighting tubes are 12/8 inches in diameter (the “T-“designation refers to a tube’s diameter in terms of 1/8 inch increments). T-12 tubes consume significant amounts of electricity, and also have extremely poor efficacy, lamp life, lumen depreciation, and color rendering index. Because of this, the maintenance and energy costs of T-12 tubes are high. Replacing T-12 lamps with T-8 lamps (smaller diameter) approximately doubles the efficacy of the former. Also, T-8 tubes generally last 60% longer than T-12 tubes, which leads to savings in maintenance costs. Typical energy savings from the replacement of a T-12 lamp by a T-8 lamp is around 30%.

Replacing mercury lights with metal halide or high-pressure sodium lights: Where colour rendition is critical, metal halide lamps can replace mercury or fluorescent lamps with energy savings of 50%.

High-intensity discharge (HID) voltage reduction: Reducing system voltage will have a positive effect on energy conservation on the lighting system. As a rule of thumb, a 10% reduction in lighting voltage will result in an energy savings of 10%. There are commercial products on the market that attach to a central panel switch and constrict the flow of electricity to lighting fixtures, thereby reducing voltage and saving energy, with an imperceptible loss of light. Voltage controllers work with both HID and fluorescent lighting systems and are available from multiple vendors. It is important to note that these voltage stabilizers won’t have any savings with LED systems. Reducing voltage will even extend the lifetime of lights.

Daylighting: Daylighting involves the efficient use of natural light in order to minimize the need for artificial lighting in buildings. Increasing levels of daylight within rooms can reduce electrical lighting loads by up to 70%. Unlike conventional skylights, an efficient daylighting system may provide evenly dispersed light without creating heat gains. The reduced heat gains will reduce the need for cooling compared to skylights. Daylighting differs from other energy efficiency measures because its features are integral to the architecture of a building; therefore, it is applied primarily to new buildings and incorporated at the design stage. However, existing buildings can often be cost-effectively refitted with different daylighting systems like translucent sheets, light pipes etc. Various daylighting systems are available on the market, some of which can be supplied as kits to retrofit an existing building.

Daylight Harvesting  - Sky Lights

Daylighting can be combined with lighting controls to maximize its benefits. Because of its variability, daylighting is almost always combined with artificial lighting to provide the necessary illumination on cloudy days or after dark. Daylighting technologies include properly placed and shaded windows, atria, angular or traditional (flat) roof lights, clerestories, light shelves, and light ducts. Clerestories, light shelves, and light ducts accommodate various angles of the sun and redirect daylight using walls or reflectors. Not all parts of a facility may be suitable for the application of daylighting. Daylighting is most appropriate for those areas that are used in daytime hours by people. The savings will vary widely depending on the facility and buildings. Daylighting systems typically have a payback period of around 4 years, although shorter paybacks have been achieved.

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