Light Loss Factor (LLF))

LLF is used to create a safety margin to assure adequate lighting over a period of time. Good lighting design requires the designer to allow for the depreciation of the a fixture’s light output dues to dirt and age of the equipment. A LLF of 0.80 allows for a 20% degradation in the lighting level.

Load Management

The process of balancing the supply of electricity on a network with the electrical load by adjusting or controlling the load rather than the power station output.


The ability to change the amount of energy used at any given time. Load shifting can be accomplished by turning off a piece of equipment; switching to internal, off-grid power generation sources; or operation of equipment during off-peak hours.

Low Bay Lighting

Used in areas where the bottom of the luminaire is less than 20 feet above the floor, low bay fixtures are usually 22 – 28″ in diameter in order to spread the light evenly. Low bay HID lighting fixtures have optical refractors that cover the lamp and reduce glare. Their widespread distribution improves vertical illumination and permits spacings as much as two or more times their mounting height. In addition, they can be mounted up to 25′ when high vertical illuminance is required. Fluorescent fixtures are also good for low bay lighting due to their excellent uniformity and relatively low lumen package compared to HID.


A measure of the amount of light given off by the lamp in a light fixture. A fixture with a higher level of lumens gives off more light.