Published by Green by Design

A Green by Design Buying Guide – Lighting Guide (PDF format)

Introduction

This Green by Design buying guide provides information and suggestions on the various aspects of green lighting systems to help you make an educated choices about lighting. The technology of green lighting systems has greatly improved over traditional methods of both indoor and outdoor lighting. This guide discusses the green aspects of artificial light, natural light, light fixtures and lighting maintenance. All of these components should be considered in order to effectively increase the energy efficiency of lighting.

The tradition of incandescent lighting uses electricity to heat a thin filament until the heated filament emits light. Unfortunately, the energy transfer in incandescent lighting is very inefficient, so this method is now being replaced by more efficient lighting systems. Many new systems contain ballasts, which are devices that limit the amount of current in the circuit.

To reduce the amount of electrical energy needed to produce an equivalent amount of incandescent light, ballasts are included in the design of fluorescent lamps, compact fluorescent lamps (CFL), high intensity discharge (HID) lamps, light-emitting diodes (LED) and other forms of lighting.

As the demand for more energy efficient systems continues to increase, many countries around the globe are attempting to ban the use of inefficient, incandescent light. Consumers may readily identify green, energy efficient lamps and light fixtures by looking for an ENERGY STAR label on the product. ENERGY STAR is an internationally recognized symbol, which specifies that products deliver the same or better performance as comparable models while using less energy and saving money.

What Makes Lighting ‘Green’?

In lighting systems, greening represents methods to reduce or eliminate electrical consumption, which in turn reduces emissions from fossil fuels and contaminants generated by utility companies. Your purchase of energy efficient light bulbs, light fixtures and lighting systems will reduce your energy costs and help the environment. There are several components of lighting to consider when greening your lighting, as described below.

Light Source

The most effective greening techniques for lighting systems involve the use of natural light, battery powered light, and solar powered light. These systems require no electrical power for use. In fact, the only electrical energy consumption associated with these types of systems is in their manufacture and installation.

Technological advances are constantly evolving to further reduce energy use for both industries and consumers. The chart below rates types of lighting according to their ability to reduce or eliminate electrical consumption.

Types of Lighting by Ability to Reduce or Eliminate Electrical Power

	TYPE OF LIGHTING	EXAMPLES	GREEN BENEFIT
Most Efficient	Natural Lighting	WindowsSkylights	Requires no power.
	Battery Powered Lighting	Flashlights	Requires the battery’s internal power.
	Solar Powered Lighting	Outdoor accent lighting	Requires battery power to store needed energy.
Least Efficient	Electrical Lighting	All other light sources	Requires electrical power.

The most efficient types of lighting provide limited lighting not likely to meet the majority of your lighting needs.

Light Needs

You need to consider how light will be used in a particular space. There are three primary types of artificial lighting used for both indoor and outdoor lighting as shown below.

Three Main Types of Artificial Lighting

Light Quantity

When choosing a lighting system, you need to understand how light is quantified. Terms used to quantify lighting include watts, lux, lumens, and efficacy.

Watts

Wattage for light bulbs, such as 100-watt, is a measure of the amount of energy that the bulb uses per hour. Wattage is determined for light bulbs (lamps) and light fixtures. Different types of bulbs and fixtures use generate different amounts of light from an equal amount of energy. Green light bulbs and light fixtures produce more light than traditional incandescent light bulbs while using an equivalent amount of electricity. Traditional incandescent light fixtures use electricity or line voltage. As such, these fixtures operate by screwing a bulb into the socket and no additional components are needed to produce light. More efficient fixtures require ballasts or other devices in order to operate efficiently.

Lux

Lux is the unit measure of illumination. A lux is the equivalent of one lumen per square meter. Some common approximations of lux are shown below.

Common Approximations of Lux

Lumens

Lumens are a measure of luminous flux or the quality of light emitted from a light source, as the human eye perceives it. Lux refers to the distribution or intensity of light on a horizontal surface. A traditional incandescent light bulb distributes light onto a horizontal surface in a 360-degree spherical pattern. As a reference, a 100-watt incandescent light bulb distributes approximately 1750 lumens of light whereas a 60-watt bulb distributes approximately 800 lumens of light over the same area.

Efficacy

The energy efficacy of light is a measure that differs from the measure of illumination. Energy efficacy is measured as the ratio of illuminated light (expressed in lumens) to the energy consumed by light (expressed in watts). The transition to green lighting systems requires a change of mindset. Consumers need to focus on lumens rather than wattage.

Light Quality

The quality of light is determined by three factors: color temperature, color rendition and glare.

Color Temperature

Color temperature defines the color of a light source in the range of warm to cool. Yellow-red colors, such as those in the flame of fire, are considered warm. In contrast, blue-green colors, such as those in an overcast sky, are considered to be cool. Color temperatures are measured in degrees Kelvin (^oK) with temperatures in the range of 3,600 ^oK – 5,500 ^oK considered cool and temperatures in the range of 2,700 ^oK – 3,000 ^oK considered warm. In contrast to environmental temperatures, higher color temperatures represent cool and lower color temperatures represent warm. Cool temperatures are closer to natural daylight while warm temperatures are preferred for living spaces since they tend to be more flattering to skin tones and clothing.

Color Retention

Color retention describes how colors appear when they are illuminated by a light source. Since most objects are composed of multiple colors rather than a single color, some light sources tend to change the color of objects. A Color Retention Index (CRI) is used to indicate a light source’s ability to render colors in the same fashion as sunlight. CRI is based on a scale of 1 to 100 with 100 being the illumination produced by a 100-watt incandescent light bulb. Using energy efficient light bulbs, the CRI-100 index may be achieved using less electricity.

Glare

Glare is a measure of the excessive brightness from a direct light source on an object. Glare makes it difficult to see an object and it results from the placement of an object relative to the light source. Placing a light object in front of a dark background will cause glare. Bright incandescent lamps are more likely to produce glare than large fluorescent lights.

Light Controls

Light controls are used to reduce the amount of time for which lights are turned on.

Dimmers

Dimmer control devices allow you to vary the level of lighting. Dimmers reduce energy costs when used at low levels of dimming. Fluorescent dimmers are dedicated fixtures, which are more energy efficient than traditional fluorescent light bulbs.

Photosensors

Photosensor controlled devices respond to ambient light to turn off during daylight hours and turn on at night. Some photosensor devices can be programmed to cut on at dusk and remain on for only a predefined number of hours or minutes.

Occupancy Sensors

Occupancy controlled sensor devices are designed to detect activity, turn on when there is activity and turn off when such activity ceases. There are two forms of occupancy sensors. Ultrasonic sensors respond to sound and infrared sensors respond to heat and motion. Motion sensors are a form of infrared occupancy sensors, designed to respond to motion only.

Timers

Timers are control devices that may be set to turn on and off at predetermined times during a 24-hour period.

Light Maintenance

The energy efficiency of any lighting system is increased with proper maintenance since the level of light decreases with the aging and discoloration of lamps as well as dirt on the fixtures, the lamps or the walls within a room. These conditions may reduce the total illumination by as much as 50%. However, the light will continue to use the same amount of energy. Some simple maintenance tips to preserve the efficacy of light are shown at in the chart below.

Maintenance Tips for Lighting

Product Comparison

The chart below includes specifications for incandescent, fluorescent, high-intensity discharge and solid-state lamps.

Lighting Product Comparison 1
Lighting Type	Efficacy (lumens/watt)	Lifetime (hours)	CRI2	Color Temp (K)	Indoor / Outdoor
Incandescent
Standard “A” bulb	10-17	750-2,500	98-100 (excellent)	2,700-2,800 (warm)	I/O
Tungsten halogen	12-22	2,000-4,000	98-100 (excellent)	2,900-3,200 (warm to neutral)	I/O
Reflector	12-19	2,000-3,000	98-100 (excellent)	2,800 (warm)	I/O
Fluorescent
Straight tube	30-110	7,000-24,000	50-90 (fair to good)	2,700-6,500 (warm to cold)	I/O
Compact fluorescent lamp (CFL)	50-70	10,000	65-88 (good)	2,700-6,500 (warm to cold)	I/O
Circline	40-50	12,000			I
High-Intensity Discharge
Mercury vapor	25-60	16,000-24,000	50 (poor to fair)	3,200-7,000 (warm to cold)	O
Metal halide	70-115	5,000-20,000	70 (fair)	3,700 (cold)	I/O
High-pressure sodium	50-140	16,000-24,000	25 (poor)	2,100 (warm)	O
Low-Pressure Sodium	60-150	12,000-18,000	-44 (very poor)		O
Solid State
Cool white LED	47-64	35,000-50,000		>5,000	I/O
Warm white LED	25-44	35,000-50,000	80	2,600-5,000	I/O

Incandescent lamps are the most inefficient of lamp types even though they provide excellent color retention. They are the least expensive to purchase, but they are the most expensive to operate. Incandescent lamps also provide the shortest average life.

Long-life incandescent light bulbs are a variation of standard “A” bulbs, which have a thicker filament. They offer a longer life, but long-life bulbs are even less energy efficient than standard bulbs.

Tungsten halogen lamps also include a filament, as do all incandescent lamps, but they are more energy efficient than standard “A” bulbs. Tungsten halogen lamps include a gas filling with an inner coating to reflect and recycle heat to keep the filament hot, thereby reducing the consumption of electrical energy. They are more expensive to purchase than standard “A” bulbs, but less expensive to operate. Tungsten halogen lamps are typically used for accent lighting.

Reflector lamps (type R) include floodlights and spot lights, which direct and distribute light to a specific area. There are two types of reflector lamps. Parabolic aluminized lamps (type PAR) are used for outdoor lighting. Ellipsoidal lamps (type ER) focus and project light approximately two inches to the front of its enclosure. They are typically used to project light downward from recessed light fixtures. Type ER reflector lamps are twice as efficient as type PAR lamps in recessed lighting fixtures

Fluorescent lamps provide the same amount of illumination as incandescent lamps while using 25% to 35% of the energy required for incandescent lamps. They also last 10 times longer.

Straight tube lamps produce an electric current, conducted through the mercury and inert gases inside of the fluorescent tube. This allows the phosphor coating located on the glass to emit light.

Ballasts are used to generate a high start-up voltage and then regulate the operating current. Electronic ballasts have replaced the electromagnetic ballasts used in traditional fluorescent lamps. Electronic ballasts operate at high frequencies and eliminate the flicker and noise that was inherent in traditional fluorescent lamps.

CFL lamps operate in a similar manner as straight tube lamps except that some CFLs have dedicated ballasts, which allow CFLs to be used as replacements for traditional incandescent lamps. The following chart shows the approximate wattage of an incandescent lamp versus an ENERGY STAR qualified CFL lamp.

Incandescent vs. CFL lamps

HID lamps provide the same amount of illumination as incandescent lamps while saving 75% to 90% of the energy required for incandescent lamps. HID lamps offer the highest efficacy and life of any type of light. Intense light is produced from an enclosed electric arc. HID lamps require ballasts, which take some time to establish the electric arc. This may create as much as a ten-minute delay between turning the light on and the actual production of light.

Mercury vapor lamps were traditionally used for street lighting, arenas and gymnasiums.

Metal Halide lamps are used to replace most mercury vapor lamps that were traditionally used in arenas and gymnasiums since they offer better color rendering and higher energy efficiency. Even greater energy savings may be realized by replacing mercury vapor lamps with high-pressure sodium lamps.

High-pressure sodium lamps provide poorer color rendition than metal halide lamps, but they offer a longer life. This type of lighting has become the preferred choice for outdoor lighting.

Low-pressure sodium lamps are more energy efficient than high-pressure sodium lamps, but they offer poor color rendition. This type of lighting is typically used where color is not essential, such as on highways and as security lighting.

Solid-state lamps are the newest and fastest growing technological innovation used in lighting. Data to characterize lights in this category are scarce and continuously evolving.

LED lamps are solid-state lamps that illuminate and direct light, dependent upon the shape and composition of the lenses and the package structure.

What To Look For

If your home has windows that face north and south, you can expect to achieve more benefit from daylight than if your home has windows that face east and west. Windows that face south allow the most winter daylight to enter and they allow little direct sunlight to enter in the summer. Windows that face north allow relatively even amounts of daylight to enter with little glare and very little direct sunlight in the summer. Windows that face east allow sunlight in the morning while windows that face west allow sunlight in the evenings. However, the sunlight may cause glare, allow for excessive heat in the summer and contribute very little to solar heating systems during the winter.

Choose fluorescent lamps for high-demand ceiling and wall lighting that typically remains on for two or more hours.

Choose light wall colors to reduce the need for artificial light.

Carefully inspect light bulb packaging for its ratings of lumens, watts and life. The higher the number of lumens, the more light it provides. The lower the number of watts, the more you will save in utility costs. The higher the life, the less often you have to replace the lamp. Choose the number of lumens to suit your needs and then seek a lamp with the least amount of watts to achieve that number of lumens.

HID lamps take time to generate light and are most suitable for situations where a light is used for hours at a time. They are not suitable for use with motion sensors.

Summary

Look for light bulbs and fixtures that indicate ENERGY STAR compliance. Also seek lighting fixtures that are approved by the Underwriters Laboratory (UL). The UL symbol specifes that fixtures are airtight, insulation contact (IC) rated, and meet safety standards.

Sources

http://apps1.eere.energy.gov/consumer/

http://oee.nrcan.gc.ca/energystar/english/pdf/basic-facts-residential-e.pdf

http://www.brillianz.co.uk/data/documents/Lumen.pdf

http://www.energystar.gov/index.cfm?c=about.ab_index