What is High Bay Lighting and its Uses

WhitePaper_luminaires_highbay-myledlightingguideWhat is a High Bay? In the world of lighting, it is a fixture that you may find in a warehouse, a factory, a gym, an airport hangar or any large open area industrial and commercial space with relatively high ceilings. Drive by any industrial park, warehouse, or factory, and walk inside and what you will see is a high bay light.

But walk into any factory or warehouse and you will see different styles and options, wattage’s and configurations. Traditional high bay fixtures that were once common place were Mercury Vapor, which were then replaced with High Pressure Sodium and Metal Halide bulbs. As new technologies were introduced, and old technologies became more common, the old HID bulbs were replaced with Induction and Fluorescent light sources. And more recently with the more wide spread approval and popularity of LED, we started to see conversions from these older technologies to the latest energy saving LED High Bays.

What is a high bay light fixture?

A High Bay Fixture, depending on the light source, can take on many forms and shapes. If you consider a Metal Halide or High Pressure Sodium fixture, they typically consist of a large heat sink block at the top of th

e fixture that ty

pically houses the fixtures ballast. Below is an aluminum or acrylic dome and at the top of the dome is the HID bulb. These bulbs typically come in two wattage’s, 400 and 1000. 400 Watt Fixtures tend to be installed in ceiling heights no higher than 30 feet, 1000 watt fixtures are typically

40 feet or higher. Interestingly enough, spacing of lights is similar to the

height they are located off the floor. A fixture installed at 20 feet from the floor is installed in a 20X20 pattern, 30 feet in a 30X30 pattern, 40 feet in a 40X40 pattern. Of the 3 type of HID bulbs, Metal Halide tends to be the best option. High Pressure Sodium Bulbs are very low on the temperature color and have the lowest CRI (Color Rendering Index) which is a measurement of light quality. Some Mercury Vapor bulbs also can have low CRI, but not all do, and the color temperature seems to range between 3500K and 6000K. Although you see some Mercury Vapor bulbs installed, it is more common to see Metal Halide and High Pressure Sodium.

A few years back, factories and warehouses started to convert over to fluorescent technology. Even fluorescent lights went through a change, from T12, to T10,

T8 to T5 technology. With every change, the conversion to this technology meant the energy saved per fixture would go down. Today, you can replace a 400W Metal Halide High Bay with a 6 tube T5 54W HO fixture. Total energy consumption goes from 455 watts for the metal halide fixture to 360 watts for the T5 6 tube fixture. These consumption values also includes ballast draw. Essentially, and fixture that uses a ballast to drive the light source also consumes a small percentage of energy in the process of what the ballast does, typically a 15% addition in terms of draw.

Then along came LED Technology, and early adoption was slow because of the newness of the technology and cost. Early models were not all that efficient, typically in the 70 lumens per watt range. While still more efficient than the counterparts it replaced, the cost of using this technology made it almost too expensive to use. Paybacks for reduced energy consumption was 3+ years, sometimes as much as 6+ years. But like any technology, advances are made, cost is reduced, and adoption rates rise. So today, the efficacy standard is much higher. When converting from Metal Halide to fluorescent T5, one could realize an energy savings of 21%. When converting the same fixture over to the new ultra efficient LED High Bays, one can expect to see a savings of 65% or more.

Choosing the correct High Bay Fixture

Choosing the right High Bay fixture can mean the difference between a successful lighting project or a failure. Not only are there many fixture types to choose from, but many options as well. And the options also include energy saving options that could translate into massive savings for the facility owner. And article published by the US Dept of Energy talks about several options facility owners can undertake to essentially reduce cost.

For the most part, high bays fixtures have evolved to be very specialized and task specific. High Bays designed for warehouse aisles have the ability to focus the light where it is needed. A light designed for a warehouse aisle is a lot different than a light designed for a gymnasium or a factory floor. In these spaces, a light that can flood the area evenly is important, in a warehouse aisle, a light that can light up the face of the shelves and the floor below is important. And when selecting energy efficient options, its just as important to understand the technology and what it is capable of doing. Adding controls to a T5 fluorescent fixture is a good idea only if the ballast is designed to handle that requirement and not lower the life expectancy of the bulbs. Motions sensors and daylight controls that dim the light output based on occupants and the amount of daylight available in the space. Technologies such as metal halide and high pressure sodium are not a good choice as these technologies are not good at dimming or turn on or off quickly. Fluorescent can dim, but you need special ballasts for them. So knowing what you want to do and may want to do is important at time of purchase, because not having the proper equipment or options could mean a costly retrofit somewhere down the road.

With the advent of ultra efficient and cost effective LED, the old arguments of the past no longer seem to hold much weight. LED technology has taken tremendous leap forward in the past 3 years. Increased adoption rates, more factory production, lower costs and dramatic progress in LED efficiencies have placed LED in the forefront of lighting warehouses, factories, gyms and hangars. LED should be thought of more as a technology as opposed to a light source. The ability to dim, turn on and off, and be part of a control network means that it is more than just a light, it is a system. And with any system, it can be optimized to perform in a specific way, including saving energy. In terms of High Bay fixtures, this means dimming or turning off lights when no one is around. It means designing the light specifically for the need. It means that the technology is future proof so that additional functions can be added in the future. And even with none of the technology upgrades installed, you can expect a 65% or greater savings over Metal Halide and a 50% or greater savings over fluorescent technology. Pay backs have dropped significantly, rebates to purchase are readily available through the utility companies, and mass adoption means the technology of LED had matured to the point where the questions and disbelief of past years have gone away.


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