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Energy Efficiency – HID Lighting

Lee Layton, P.E.


Course Outline

The course begins with a review of the U.S lighting market in various sectors such as residential, commercial, industrial, and outdoor lighting.  Chapter two covers the fundamentals of lighting including how light is transmitted, reflected, and how color is discerned.  Chapter three discusses the characteristics of HID lamps and Chapter four reviews the characteristics of the different types of HID lights including Mercury Vapor, Low and High Pressure Sodium, Metal Halide, and Xenon lamps.

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

After taking this course you should:

Intended Audience

This course is intended for anyone who wants to understand how HID lamps operate and are used in the energy markets.

Benefit to Attendees

HID lamps are an important component in commercial, industrial, and outdoor lighting and they are unlikely to be replaced by LED lamps for some time.  This course will give the reader a good understanding of how HID lamps operate and the types of applications that are best suited for HID lamps.

Course Introduction

Gas-discharge lamps are light sources that generate light by sending an electrical discharge through an ionized gas. The character of the gas discharge depends on the pressure of the gas as well as the frequency of the current.  High-intensity discharge (HID) lighting provides the highest efficacy and longest service life of any lighting type. It can save 75%-90% of lighting energy when it replaces incandescent lighting.

HID lamps use an electric arc to produce intense light. Like fluorescent lamps, they require ballasts. They also take up to 10 minutes to produce light when first turned on because the ballast needs time to establish the electric arc. Because of the intense light they produce at a high efficacy, HID lamps are commonly used for outdoor lighting and in large indoor arenas and they are most suitable for applications in which they stay on for hours at a time.

The three most common types of high-intensity discharge lamps are:

Mercury vapor lamps are the oldest types of high-intensity discharge lighting and have been used primarily for street lighting.  Mercury vapor lamps provide about 65 lumens per watt. They cast a very cool blue/green white light.  Mercury vapor lamps have lifetimes of up to 24,000 hours.
 
Metal halide lamps produce a bright, white light with the best color rendition among high-intensity lighting types. They are used to light large indoor areas, such as gymnasiums and sports arenas, and outdoor areas, such as car lots.  Metal halide lamps are similar in construction and appearance to mercury vapor lamps. The addition of metal halide gases to mercury gas within the lamp results in higher light output, more lumens per watt, and better color rendition than from mercury gas alone.  Metal halide lamps have shorter lifetimes than mercury vapor and high-pressure sodium lamps.

High-pressure sodium lighting is the most common type of outdoor lighting.  High-pressure sodium lamps have an efficacy of up to 140 lumens per watt—an efficiency exceeded only by low-pressure sodium lamps. They produce a warm white light.  Like mercury vapor lamps, high-pressure sodium lamps have poorer color rendition than metal halide lamps but longer lifetimes.

The first mercury vapor lamp was invented in 1901 by American engineer Peter Cooper Hewitt. In 1903, Hewitt created an improved version that possessed higher color qualities which eventually found widespread industrial use. The Hewitt lamps used a large amount of mercury. In the 1930s, improved lamps developed by the General Electric Company and others led to widespread use of mercury vapor lamps for general lighting.

The introduction of the metal vapor lamp, including various metals within the discharge tube, was a later advance. The heat of the gas discharge vaporized some of the metal and the discharge is then produced almost exclusively by the metal vapor. The usual metals are sodium and mercury owing to their visible spectrum emission.

In this course, starting with Chapter One, we will review the overall lighting market to get a sense of how HID lighting is participating in the marketplace.  Chapter Two reviews the fundamentals of lighting and Chapter Three covers the basic characteristics of all HID lighting. In addition to the three major types of HID lighting just mentioned, there are variations and these will be discussed in more detail in Chapter Four. 

Course Content

This course content is in the following PDF document:

Energy Efficiency – HID Lighting

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Course Summary

High-intensity discharge (HID) lighting provides the highest efficacy and longest service life of any lighting type. It can save up to 90% of lighting energy when it replaces incandescent lighting.  High-intensity discharge lamps make more visible light per unit of electric power consumed than fluorescent and incandescent lamps since a greater proportion of their radiation is visible light in contrast to heat.

HID lamps use an electric arc to produce intense light. Like fluorescent lamps, they require ballasts. They also take up to 10 minutes to produce light when first turned on because the ballast needs time to establish the electric arc. Because of the intense light they produce at a high efficacy, HID lamps are commonly used for outdoor lighting and in large indoor arenas and they are most suitable for applications in which they stay on for hours at a time.

Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.