How to reduce lighting costs in hi-bay environments
In high-bay environments, such as warehouses, distribution centers, production facilities, and other industrial spaces, ineffective lighting is especially common. This is because these areas are not populated on a regular basis, but the lights typically remain on at all times. The good news is improvements in high-bay lighting systems can yield significant savings to the overall operational costs of this type of facility.
Two of the most effective ways to reduce lighting costs in high-bay environments are upgrading the luminaires and installing lighting controls. Although most customers understand the energy savings they can realize by upgrading luminaires, many overlook the fact that an additional savings of 50% to 75% can be gained when high-bay occupancy sensors are also incorporated into the retrofitted lighting system. This layered approach of efficient lighting, coupled with occupancy-based controls, significantly reduces energy and maintenance costs.
Applications like warehouses and other industrial facilities, which have occupancy rates less than 50% and feature high ceilings (15 ft to 45 ft), are ideal candidates for sensors. Consider a large warehouse with many long rows of racks and shelves loaded with merchandise as an example. When an order is issued, the picker identifies the aisle the product is on and drives a forklift into the space to fill the order. If the facility is not equipped with occupancy sensors, then the entire area is lit before and after the picker enters the space — even if there is no one else around. This arrangement wastes energy and results in higher costs.
Consider the same warehouse with high-bay occupancy sensors in place. The sensors will either detect movement of the approaching forklift or a change in heat in the area and turn on the lights. Sensor coverage patterns are broad enough to identify activity and turn on the lights well before the forklift enters the space so that the driver can see. Then, with the programmable timer, the lights will again be turned off after a set period of inactivity. Clearly, using lighting control sensors in this scenario significantly reduces energy consumption levels and operating costs.
One of the key components of a high-bay occupancy sensor is the lens that determines the coverage pattern for the particular sensor. In high-bay applications, the most common types of coverage patterns are 360° and aisleway.
Figure 1 (click here to see Fig. 1) illustrates the coverage pattern for a high-bay occupancy sensor with a 360° field of view. This device looks down from either the high-bay fixture or the junction box that it’s mounted on, and covers a circular area extending out from the attachment point directly below the mounting position. The size of this circle depends on the mounting height of the device.
Figure 2 (click here to see Fig. 2) shows the coverage pattern for an aisleway occupancy sensor. This sensor has a special lens that directs coverage on the aisleway instead of areas with racking. The segments of the lens also enhance the coverage of the sensor so that fewer units can be used in an aisleway application.
It’s easy to understand that occupancy sensors will reduce costs for your customers. The examples shown in the Table on page C36 represent actual data captured from 100,000-sq-ft to 250,000-sq-ft warehouse facilities, clearly illustrating savings of up to 69% or more. Multiplying a company’s annual energy bill by the applicable savings percentage shows the annualized savings achievable by installing sensors. In some applications, payback for installation is measured in months.
The bottom line is high-bay lighting controls represent a significant opportunity for companies to cut their overall energy consumption. Additionally, using lighting controls will decrease maintenance costs. By reducing the amount of time the lights stay on, occupancy sensors extend the calendar life of the lamps in the fixtures, minimizing both lamp replacement costs and maintenance costs for replacing burned out lamps. Lastly, installing occupancy sensors may offer tax deductions for building owners. For example, the EPAct tax incentive provides a deduction for installing a qualifying energy-efficient lighting system to either an existing or new commercial building.
Hahn is VP of Acuity Brands Lighting, Wallingford, Conn. He can be reached at ben@sensorswitch.com.