We should start this by saying that high bay lighting is lighting that is generally located at distances above 25 feet from the floor. Such is the case with warehouses, industrial production, commercial, big box retail, and other high ceiling facilities such as gymnasiums and auditoriums. The design and construction of many of these facilities are formed by a skeletal framework that creates an interior space that is referred to as a “bay”, either high or low depending on the distance between the ceiling and floor.
In a high bay situation, the lights used must be powerful enough to illuminate the area to a point that task lights are not necessary because, in most cases, task lighting is not appropriate. This necessity requires powerful and highly directional light. The common way to help accomplish the feat is by using spun aluminum reflectors, as traditionally used in high output lights such as seen with metal halide and other traditional high output lights, or reflective fixtures such as seen in fluorescent lighting. The other part, the power, is accomplished by the lights themselves. This power is noted in the form of watts and lumens, the wattage is generally in the 400 watt region, and the lumens might range from an initial 36,000 in a single metal halide, down to around 22,000 lumens for a super T-8, six tube fluorescent fixture.
The problems with traditional high bay lighting are numerous. Just the maintenance issues that go along with replacing components in traditional high bay lighting is very high compared to modern LED lighting. With HID fixtures, such as metal halide lighting, just the startup time is an important factor. Initial startup is not immediate and a restart is even more time consuming, even with the newest pulse-start ballast systems, which might be used to replace outdated probe-start systems. HID lights also shut down when high temperatures are reached. The pulse-start metal halide lights may provide an energy savings of up to 25% over the dated probe-start systems, and fluorescent T-8 or T5HO can reduce energy savings of up to 50% over the metal halide. Lumen depreciation is also a factor in the use of HID and fluorescent lighting. HID lights, for example can lose up to 35% of their light output at the typical time of 40% of life. High output fluorescent – T-8 or T5HO – typically lose only about 5-6%. However, none of the traditional high bay lighting can compete with modern LED high bay lighting.
The modern high bay LED lighting systems are miles ahead of the older types of lighting used in the same situations. LED energy savings over HID lighting is typically in the region of 50% or more. LED energy savings over fluorescents is more likely to be in the 10% range but the lifetime of the LED is extremely high compared to either of the older technologies. The average life of quality LED systems is upwards of 150,000 hours compared to 35,000 for fluorescents and less than 20,000 hours for metal halides. That kind of lifetime certainly outdoes the older technology, thus eliminating all the maintenance involved with older lighting. Not only is the more frequent maintenance costly, but it can be dangerous and might only be trusted to a professional tech simply due to the heights involved. The initial cost of LED systems is a bit more than more traditional systems but the payoff for the LED’s is multifold; energy savings, longer life, less degradation of lumen output, CRI, and color temperature over the life of the light. Also, the initial cost can be reduced by available energy incentive program rebates through local utility companies. All facts taken into consideration, the LED high bay in today’s world outperforms any older high bay technology by such a large margin that the overall savings cannot be beaten by other older technology.