Publication: Upgrade high bay lighting for energy savings

This paper is an information resource for building managers looking to upgrade high bay lighting to reduce energy costs.

Introduction to high bay lighting

High bay lights are used widely in the industrial and commercial sector; for manufacturing, processing, storage, and even sporting facilities. The high energy usage of high bay lighting driving up energy costs is a common issue to many businesses. Looking at the best options to reduce the energy usage of high bay lighting is part of many of our energy audits. One high bay lamp may consume 400W (plus >50W for the ballast). An array of high bay lights running during peak electricity periods not only increases electricity kWh usage costs but also peak demand and capacity network charges.

Options to upgrade 400W mercury vapour high bay lights

If your site has 400W mercury vapour high bay lights than chances are they may be >10 years old and getting close to the end of their life. This provides a good opportunity to upgrade with a more energy efficient option. The higher cost for energy efficient fittings should be more than offset by savings off energy bills. High pressure sodium HPS lights have a greater efficiency but have a poor colour rendition with a characteristic yellow light that is not suitable for interior use. The following are suitable options to upgrade 400W mercury vapour high bay lights.

• 300W Metal Halide luminaire
• 250W Pulse Start Metal Halide luminaire
• 200W Induction lamps luminaire
• 4 x 54W High Output T5 fluorescent tube luminaire
• 100W to 150W LED luminaire

Upgrading high bay lights may provide an opportunity to install motion sensors.

It is typically not recommended to control Mercury Vapour, High Pressure Sodium, and Metal Halides with motion sensors due to long start-up / re-strike times. In fact these lights are switched on at the beginning of day and left running until close.

Induction lamps, LEDs and T5 fluorescent tubes are typically compatible with occupancy sensor controls. However frequent switching may reduce lamp life. LED high bay lights are the best choice for integrated occupancy sensor controls.

Zoning

At many sites all high bay lights are switched on a common circuit to turn on together. Appropriate zoning is critical to reducing high bay energy usage. This will enable lights in unused areas to be switched off, for example switching lights off over unused process lines. Some areas may have different lux level requirements depending on the type of work being conducted. Appropriate zoning allows more lights to be switched on when higher level tasks are being conducted (e.g. machining) and lights to be switched off when lower level tasks are being conducted (e.g. storage). Regardless of the control and zoning strategy it is always a good idea to leave some passageway lighting on during working hours.

Daylight harvesting

Other energy saving options: Active Reactor controller

There may be an opportunity to use the Active Reactor controller, either retrofit into existing fittings or installed in new luminaries as part of an upgrade. The Active Reactor controller saves energy by maintaining a constant lumen output over the life of a lamp. The voltage is reduced for new lamps that have a high initial light output, as the output of the lamp decreases over time the voltage is automatically ramped up to maintain a constant lumen output. This controller is used in some street lights. Energy savings of up to 20% for high pressure sodium (HPS) lamps and 15% for metal halides (MH) may be achieved.

Other issues to consider when upgrading high bay lighting

There are a number of issues to consider when upgrading mercury vapour high bay lights:

• Cost savings are dependent on current and future electricity charges including network demand/capacity charges and the carbon tax. With significant changes to network tariff structures in many network areas, uncertainty in the electricity market and environmental charges it is important to carefully consider the cost benefits of upgrading lighting.
• Upgrading high bay lighting may significant change the power factor of the site at peak demand and effect network demand and capacity charges for sites on a kVA tariff.
• Access to lights, plant shutdown and the need for lifts can all significantly increase the cost and complexity of upgrading high bay lighting.

What option is best to upgrade high bay lights?

This question of what option(s) is best for your site is dependent on many factors and should be determined by an energy audit. Some of the questions to ask are: Can lights be re-zoned? Is there natural light? Is there easy access to lights? Do lights need to meet hazardous workplace standards? Is short term payback or achieving long-term cost savings the priority?