1. Daylighting
  2. Energy Efficient Lighting by Paul Robbins of

CSI Numbers:

099 200
166 100
168 100


Daylighting optimizes natural sunlight entry into a building to minimize the need for artificial lighting. Artificial lighting is produced by electricity. Energy -efficient lighting is the use of artificial light to receive the optimal level of light for the lowest energy investment. Task lighting serves a limited area where a person’s “work” is concentrated.


The central concern associated with daylighting is the heat gain that can result when natural light is brought into a home. In our region, this is an especially important concern. During the heating season, the heat gain from natural light can be useful.

Another concern with natural light is the ultraviolet (UV) rays in natural light. When natural light strikes fabrics and some other materials, the UV rays can discolor and weaken the material.

There are simple design strategies and some materials that can facilitate the energy saving advantages of natural light. Light colored interiors and open floor plans are good choices. This approach also augments artificial light efficiency.

Energy efficient lighting is not simply finding the most light for the least wattage or the longest lasting light bulb. Proper sizing of the light to the needs of the location and the tasks that will be performed, called task lighting, is an energy saving strategy.

Light Interiors Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory
Energy Efficient Lighing Satisfactory Satisfactory Satisfactory in most conditions Satisfactory Satisfactory Satisfactory
Task Lighting Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory Satisfactory
Daylighting Satisfactory Satisfactory Satisfactory in most conditions Satisfactory Satisfactory Satisfactory
Satisfactory Satisfactory
Satisfactory in most conditions Satisfactory in most conditions
Satisfactory in Limited Conditions Satisfactory in Limited Conditions
Unsatisfactory or Difficult Unsatisfactory or Difficult



New technologies are being developed in the field of transparent insulation which would minimize heat gain from direct natural light. There are presently good design approaches and materials in daylighting and artificial lighting.


Energy efficient lighting products are readily available. Daylighting products are rare.


Energy efficient lighting products have a higher initial cost but show excellent paybacks in areas where lights are heavily used. Daylighting strategies can have a wide range of cost impacts.





No resistance other than initial cost of energy efficient lighting. There is a larger appeal to the aesthetic enhancements that can be associated with daylighting.


Standard electrical code.


1.0 Daylighting

The primary goal in daylighting is to bring in indirect light (light that is reflected and not in a direct line to the sun).

To accomplish this, overhangs on windows, which are a primary means of daylighting, must be sized to prevent direct light (light that is in direct line to the sun) from entering except, where desired, in the heating season.

Dividing the height of a wall that needs to be shaded in the summer by four will give the best size for the overhang’s projection on south facing windows.

Window height is 5 feet; height of wall above window is 2 feet;
5 feet (window height) + 2 (wall height above window) = 7 feet
7 feet divided by 4 = 1.75 feet, or 1 foot 9 inches (the length of the overhang)

It is not recommended to use east or west facing areas for daylighting purposes unless they are shaded by trees or other means. An overhang will not help block direct light adequately in east and west orientations.

1.1 Clerestory

A clerestory is a design feature suitable for open plan homes with a ceiling following the roofline. The clerestory is a windowed raised section of roof, typically consisting of operable windows, for light and ventilation. The most appropriate orientation is north or south.

South facing clerestory

There must be an adequate roof overhang above it to prevent direct solar gain in the cooling season. South facing windows can admit solar gain during the heating season due to the sun’s lower angle; fans behind the glass may direct the solar heated air into the living area or into storage. Operable windows in the clerestory also allow heat to escape from the house during the cooling season.

When light enters the clerestory, it illuminates from the highest area in the center of the house.

North facing clerestory

May require a vertical wall section on the exterior west side to prevent heat gain from the setting summer sun (which occurs in the northwest). A north facing clerestory will not experience solar heat gain in the winter. The glass should be highly insulating in this orientation or employ special insulating strategies to avoid excessive winter heat loss.

1.2 Sidelighting and Interior Colors

Sidelighting from a window is the most common source of daylighting. The amount of light decreases exponentially as you move toward the interior of the room. Light colored walls and ceilings that can reflect light in a diffuse manner will aid the effectiveness of the natural light.

North and south facing windows will provide the best light since the light can be controlled from these sources. Excessive glare and heat gain can occur from east and west orientations. South facing windows can be protected by an overhang while north windows receive direct light for a very short time in the summer.

As a general rule, the depth of a room should not exceed 2 to 2.5 times the height of the window. An overhang needs to be calculated as part of the room’s depth when used on the south side. This means that if the window is 5 feet tall and the overhang is 2 feet deep, the depth of the room needs to account for the two feet included in the overhang as part of the room’s depth. In this example, 5 feet (height of window) x 2.5 (depth ratio) = 12.5 feet- 2 feet (overhang) = 10.5 feet (room depth).

Horizontally-oriented windows high on a wall will permit the best penetration of light into a room.

1.3 Reflected Light

Reflected light can be achieved with light shelves and louvered window coverings. The primary drawback is that direct light is needed. Venetian blinds with a reflective coating on the top surface of the slats can be angled to bounce the light to the ceiling. A light colored ceiling will illuminate from the reflected light. A horizontal reflective surface placed near the top of a window (light shelf) will similarly reflect light to the ceiling and deep into a room.

Reflecting direct light to the ceiling reduces glare and provides effective deep penetration of natural light.

1.4 Skylights

Skylights are generally sources of excessive heat gain in our area. They can also cause excessive heat loss in the winter. The following guidelines will help you use skylights advantageously:

Use a translucent glazing which reduces glare.If using clear glazing, use a ceiling diffuser at the bottom of the skylight shaft to improve light distribution.

At the minimum, use double glazing.

Provide an interior insulating shade or panel to seal off the skylight shaft from nighttime winter heat loss unless special highly insulating glass is being used.

Use an exterior shading system over the skylight during the summer.

There is a skylight product specifically designed for daylighting purposes. It uses a pipe with a reflective interior to bounce the light down the pipe to a ceiling diffuser from an acrylic dome skylight on the roof. This is a method to bring natural light to a dark interior area of a home without constructing a costly light well (See Resources).

2.0 Energy Efficient Lighting

The primary strategy in energy efficient lighting lies in a design that recognizes what will occur in the area to be lit and sizes the lighting to that task. It is also important to consider the quality of the light, which can affect the level of comfort.

In a kitchen, the light requirement over the counter where tasks such as cutting and reading can occur is greater than the light needed for general activities in the room. The counter area should approximate 50-100 foot-candles (a measurement of illuminance) whereas the general light for the kitchen should be 20-50 foot candles. The amount of energy needed to produce that amount of illuminance depends on the distance to the light source. With a shorter distance more illuminance will be available in a defined area which is the reason task lighting can be conserving.

A dining area requires even less illuminance — 10-20 foot-candles — while a relaxation/entertainment area needs only 5-10 foot-candles.

2.1 Cove Lighting

A general goal is to minimize the amount of artificial light needed for “background” light (the light needed to pass through or function safely in the house). This can be accomplished with the use of cove lighting. Cove lighting is characterized by the use of ledges, valances, or horizontal recesses that cause the light to be distributed over the ceiling and upper wall. Cove lighting can be provided by low wattage fluorescent lamps or low voltage lights concealed behind a decorative valance in the upper third of the wall. The low wattage fluorescent lamps conserve energy and are long lasting. The reflected light off the ceiling provides even light throughout the room.

2.2 Daylight – Responsive Lighting and Occupancy Sensors

Daylight – Responsive

In rooms that receive natural light, there can be a frequent varying requirement for artificial light according to how bright it is outside. A fluorescent light with a “daylighting” ballast will vary in light output according to the light needs of the room. The fluorescent light, in this case, is conserving in its light output per wattage and the daylighting ballast is conserving by dimming the light output if natural light levels or other light sources are providing adequate light.

Outdoor Lighting

In outdoor lighting, photocells will respond to daylight levels and activate the outdoor light operation when darkness arrives.

To be most conserving in an outdoor application, combine the photocell with an infrared or ultra-sonic detector (see following). The photocell activates the lighting circuit for nighttime operation and the sensor turns on the light only when needed by responding to the presence of people.

Occupancy Sensors

In rooms that do not have natural light, an occupancy sensor can prove highly conserving when connected to background lighting. The sensor will operate the lights only when people are in the room.

There are two general types of occupancy sensors: infrared and ultra-sonic. Ultra-sonic sensors are best in rooms with partitions or dividers. Infrared sensors are better for open areas. Some sensors include both features. Integrated units that include the sensor and relay in a single housing that fits into a standard electrical box are priced more reasonably for residential applications.

2.3 Timing Devices and Dimmer Controls

Timers turn lights on and off at predetermined times.

Photocells respond to light levels and do not need rescheduling.

Dimmers will reduce the light level and will only save energy when used consistently.

The New Alternatives for Home Lighting

By Paul Robbins
(The remainder of this article first appeared in the 2013 Austin Environmental Directory and at

CFL Lighthouse illustration by John Dolley

Illustration by John Dolley

Light bulbs are generally the first thing that go on in people’s minds when they consider electric use in their home. However, the majority of these bulbs are still using antiquated technology that has not seen major efficiency improvements in more than a century.

Considered technological miracles at the time they were invented, the first commercial incandescent bulbs were manufactured in about 1880, and employed carbon filaments. Improved tungsten-filament bulbs were first sold commercially in Europe in about 1904, and used in America shortly after. By about 1915, they became the standard.

These bulbs are only about 10% efficient in terms of converting electricity to usable light. Yet they are still the main illumination source used in homes. About 14% of all U.S. residential electric consumption in 2010 was used to illuminate an estimated 4 billion light bulbs, amounting to about 202 billion kilowatt hours per year.

Due to technological innovations and U.S. government policy, a major conversion is underway to more efficient forms of domestic lighting. All these lamps fit into a conventional light socket and provide light similar to their incandescent ancestor. Many of them are designed to appear similar in color and brightness to gain greater acceptance from consumers.

This article is meant to answer common questions that people will have making this conversion. These new technologies also have some quirks, which will be discussed so that the buyers can avoid problems or adapt to them with minimal disruption.

The Government Is Coming to Get Your Bulbs

In 2007, the federal government passed the Energy Independence and Security Act, an omnibus energy-saving bill that included increased national standards for appliance efficiency, new loan and grant programs for retrofitting buildings, and improved mile-per-gallon standards for cars. These standards and measures were expected to be phased in over a period of years, but by 2030, they were collectively expected to save 9 Quadrillion Btus and about $80 billion in consumer costs annually. (The energy savings is the equivalent of 9% of the energy consumed in the U.S. in 2007.)

Among the law’s features was a new standard for common light bulbs. Common (A19) bulbs that are 40, 60, 75, and 100 watts in size must be replaced by bulbs at least 27% more efficient by the year 2014, and 60-70% more efficient by 2020. These common bulbs are the workhorses of the residential electric market.

By 2030, savings from upgrades to just these four sizes are expected to save 69 billion kilowatt hours, almost 2% of all the electricity used in the U.S. in 2011.

The new light bulb efficiency rules caused a knee-jerk reaction by segments of the public opposed by philosophy to regulation. Hoarding of old-line incandescent bulbs became an obsession to some people.

A news story about the subject quoted a worried, misinformed mother who believed that the new law would mandate compact fluorescent lamps, which contain small amounts of mercury. She was scared her small child would break her government-mandated bulbs and contaminate her house. Others feared encroachment of “big government” without considering that the alternative was continued price-gouging from electric utility monopolies.

Fact is, the new law does not ban incandescent bulbs. It only bans inefficient incandescent bulbs. It also exempts three-way bulbs, globes, and about 20 other types of specialty products such as ceiling fan bulbs.

The law is phased in over 3 years and prohibits selling bulbs manufactured or imported after a certain date. The residual stock of bulbs before this date may be sold, however. The phase-out dates are as follows.

Today’s Bulbs After the Standard Standard Effective Date
100 watt ≤ 72 watts 1-Jan-12
75 watt ≤ 53 watts 1-Jan-13
60 watt ≤ 43 watts 1-Jan-14
40 watt ≤ 29 watts 1-Jan-14

At the end of 2012, many stores had removed conventional 100-watt incandescent bulbs on retail shelves.

What are these new light sources?

Simply put, incandescent bulbs are a thin piece of glowing metal (filament) mounted inside a vacuum-jar (bulb) to delay oxidation of the filament. There are 3 main commercial alternatives.

1. Halogens – These are very similar to conventional bulbs. But instead of a vacuum, the bulb contains a halogen gas, allowing the bulb to use less electricity while producing the same amount of light. Depending on the design, these lamps can also have longer life than incandescent bulbs.

2. Compact Fluorescent Lamps (CFLs) – These are adaptations of conventional fluorescent tubes designed to fit in conventional sockets. Under normal conditions, their life is much longer than conventional incandescents or halogens.

3. Light Emitting Diodes (LEDs) – These are best described as semiconductors designed to glow. Clusters of small LEDs can be arranged in a lamp that fits into a conventional socket. They typically activate a phosphor coating on the inside of a bulb-shaped shell for a uniform, omnidirectional effect.

LEDs are a recent innovation in domestic lighting, and they are still relatively expensive. As the technology develops further, their price will probably fall and their efficiency will likely increase. They do, however, have a jaw-dropping life compared to incandescent bulbs, lasting up to 67 times longer, and can pay for themselves compared to incandescents several times over.

How much energy do efficient bulbs save and cost?

Chart 1 below provides an estimate of energy savings, costs, lifetime, and payback. It was drawn from a sample of Austin and Internet retailers and is not meant to be comprehensive. But it gives a good sense of the market.

Since many of these new lamps have increased lifetime compared to conventional incandescent bulbs, they can save the cost of replacement bulbs as well as energy.

Chart 1: Costs and Savings from Energy-Efficient Lamps
Energy Savings Lamp Cost Lifetime Hours Lifetime Energy Savings Lifetime Lamp Savings Payback
60 Watts
Incandescent $0.40 750-1,000
Halogen 28% $2 1,000-3,000 $3.12 $0-0.81 0.7 Years
CFL 75-78% $2 8,000-12,000 $55.00 $3.95 0.3 Years
LED 77-84% $14-52 20,000-50,000 $147.00 $10.87 2.1-8.5 Years
75 Watts
Incandescent $0.40 750-1,000
Halogen 31% $2 1,000-3,000 $4.22 $0-0.81 0.5 Years
CFL 75-78% $3 8,000-12,000 $63.00 $3.63 0.4 Years
LED 75-85% $27-59 25,000-50,000 $222.00 $13.04 3.5-8.2Years
100 Watts
Incandescent $0.40 750-1,000
Halogen 28% $2 1,000-3,000 $5.13 $0-0.81 0.4 Years
CFL 77% $3 8,000-12,000 $88.00 $3.76 0.3 Years
LED 78-85% $28-64 25,000-50,000 $328.00 $14.11 3-6.3 Years
Costs for LEDs taken March 2013. Costs for CFLs and Incandescents taken November 2012.

In general, this chart shows that, at 3 hours per day of minimal use, halogens and CFLs have fairly quick paybacks compared to conventional incandescents. It also shows that LEDs have long paybacks. Though their price has fallen markedly and quality has improved over the last 10 years, most people will not make this extra investment yet.

What the payback chart does not show

There are a huge variety of efficient lighting products. The CFLs priced here are only for the baseline (commodity) bulb. There are better quality bulbs if you want to pay the increased costs. Features include:

1) daylight and natural spectrum, which offer a color close to sunlight and higher color quality;

2) “instant-on” ability, which allows full-light output immediately instead of a warm-up period that can last a minute or more;

3) shatter-resistant polycarbonate lenses that also make a CFL twist lamp look more like a normal light bulb;

4) dimmer-compatible bulbs.

Most of these CFL upgrades usually have a payback of less than a year, but dimmer-compatible CFLs are still relatively expensive, and can have a payback as long as 2 years under typical circumstances.

Regarding LEDs, their extraordinary long life greatly reduces labor costs needed for replacement. While such costs are rarely quantified in household budgets, they are quite real. Use of LED lamps in hard-to-reach places, as well as in houses of mobility-impaired individuals, will save incredible amounts of labor and increase safety.

Another point about LED life is that these lamps do not actually burn out. Rather, they lose their brightness. Their rated life assumes that a light output reduction of 30% will be the limit consumers will tolerate.

Is there a downside to longer bulb life?

The long life of CFLs and particularly LEDs creates a relatively new problem in residential lighting. On the one hand, they offer greatly reduced maintenance. This is of particular interest to the mobility impaired, as even average people do not want to climb to hard-to-reach locations such as the top of stairways to replace a light bulb.

However, it makes lamp cleaning much more of a priority. “Lumen Dirt Depreciation” is the technical term that lighting professionals use to describe how dirt accumulation on light fixtures degrades light output over time. Even in a relatively clean environment, dirt can degrade output 14% over a three-year period. Dirty environments can see light degradation of over 50%. The only good thing about changing a short-lived conventional light bulb is that the frequency prevents you from ignoring this chore. (Get out the long-handled dust mops.)

Are Light Bulbs Air Conditioned?

Waste heat from indoor light sources has to go somewhere, and it ends up heating the house. This does assist in winter, though it is not very efficient compared to heat pumps or gas furnaces. However, in the majority of cases, additional air conditioning costs outweigh winter heating savings. While actual savings differ in every case, imagine a home using 20 100-watt light bulbs at once. This would add enough heat for an extra half-ton of air conditioning demand for every hour that they are on. Considering that the average home has a 3 to 4 ton unit, the considerable energy waste can quickly add up.

Why Do CFLs and LEDs Burn Out Prematurely?

CFLs and LEDs contain solid-state circuitry that controls them. If simple precautions are not taken, the bulbs will fail quickly, and in some cases, immediately. The best way to make these bulbs last is to remember: ACDC.

Air – Does the lamp get enough air ventilation? Unless CFLs and LEDs are specced for enclosed fixtures, the lamps may get too hot, which corrupts the circuitry. Charts 2 and 3 in this story list products rated for enclosed fixtures. If no rating exists, it is best to use these lamps in open fixtures (not flush-mounted to the wall or ceiling).

Closed fixture

Closed fixture

Open fixture

Open fixture

Cheap – Is the lamp cheap? Not inexpensive…cheap. Not every manufacturer builds good products. If you are having chronic problems with CFLs or LEDs, buy high-end brand names with guarantees. CFLs sold to homes that are rated by the Environmental Protection Agency’s Energy Star program are required to guarantee their products for two years.

Not every efficient lamp has to be expensive. If you shop, there are bargains to be had. But more often, you get what you pay for.

Dimmers – Is the lamp specced for dimmers? The circuitry in CFLs and LEDs must be specifically designed to be used with dimmer switches. If this specification is ignored, product failure can be almost immediate. Chart 2 in this article notes CFL products that are rated for dimmers. Most LEDs and halogens can be used with dimmers, though specs on product packaging should be checked.

Chart 2: Selected Brands of CFLs and Their Uses (Cost for November 2012)
This chart is meant as a consumer guide. Products constantly change, along with their specifications. Consumers should read packaging specifications or consult company to confirm information.
Energy-Star Rated Enclosed Fixtures Dimmable Model Numbers 3-Way Model Numbers Customer Service Web Site
EcoSmart 23 watts and under ES5M814DIM2 ES59032 (877) 527-0313
Feit None ESL30/100T, BPESL50/150T,
ESL50/150T/ECO (800) 543-3348
Full Spectrum Solutions 23 watts and under None BLDS253WAYT (888) 574-7014
GE All but closed recessed fixtures 66662, 66663,FLE15HT3/2/DV, FLE26HT3/2/DV 81515, 77124 (800) 435-4448
Globe Electric None 35612 None (800) 361-6761
Greenlite Corp. None 8W Dimmable CCFL A-Type 11/20/26W 3 WAY (800) 930-2111
Maxlite None None MLS33EA3WW (800) 555-5629
Osram Sylvania None 29454, 29453, 26949 CF33EL, CF40EL (800) 544-4828
Panasonic EFD13E28, EFA13E28 None None (800) 211-7262
Philips 14691-0, 13077-3, 13574-9, 37082-5 42002-6,42004-2, 42003-4, 42005-9, 40715-5 21486-6, 21193-8 (800) 555-0050
Prolume Most lamps under 27 watts 46330, 46334 45720, 45721 (800) 677-3334
Satco T2 Series S6255, S7251 S5592, S5594 (800) 437-2826
TCP 23 watts and under 40114, 40123, 50123, 41315 19030, 19032 (800) 378-6998
Utilitech All but closed recessed fixtures LBP23TDM, LBP15TDM LBP50/150T (800) 327-2080
Westinghouse None 37913, 37913 37962, 37963 (800) 999-2226
Energy Star ratings may not be on all models distributed by company.
Some lamps rated for enclosed fixtures may still have longer life if used in ventilated fixtures
Chart 3: LEDS For Use in Enclosed Fixtures (Surveyed 12/12/12)
Brand Equivalent Wattage Incandescent New Wattage Company Web site Retail Outlet
Xledia 40 7.8
Xledia 60 11
Xledia 75 11
Xledia 80 15
Xledia 100 15

Cycling – How many times do you click these lamps on and off? While the cycling effect on halogens and LEDs is not a problem, CFLs have a rated life partially based on the number of on-and-off cycles. The longer the lamp is left on at one time, the longer the life. This leads to an interesting predicament. Is it better to turn off a CFL when not in use to save energy, or use the energy-efficient lamp inefficiently by leaving it on longer and cycling it less? As a general rule, it is better to turn CFLs off when they are not needed. Lifetimes may be shortened, but the lamps are not that expensive.

The graph below shows that at 5-minute cycles, a CFL will last less than 1/10 as long as a lamp operating for 90 minutes at a time. However, even if this greatly reduced life occurs, the CFL will still more-than-pay for itself in energy savings.


Some new CFLs on the market have extended lifetimes that will accommodate for increased cycling. As a personal observation, I have seen CFLs last for 9 years, and I always turned them off when unneeded, regardless of the length of time they had been on. However, if you have certain lights that are only used for small periods of time, you might consider halogens or LEDs.

Is the energy used to manufacture these energy-efficient bulbs more than the energy savings?

Several lifecycle analyses have been done to determine how much “embodied energy” is used to manufacture lamps vs. the savings that will be derived. One of the most thorough was conducted for Osram Semiconductors, a division of Sylvania Lighting. While it can be criticized as being conducted by the manufacturer and not an objective third party, it should be noted that Sylvania makes all families of lighting products.

Primary Energy Demand for Manufacturing and Use in Kilowatt Hours – 40-watt Equivalent

The study (summarized in graph above) analyzed the energy used to create the equivalent light output of a 40-watt incandescent bulb. It found that since LEDs and CFLs last much longer than incandescent bulbs, the lifecycle manufactured energy use of both CFLs and LEDs is about 50% less. Overall, the manufactured energy use is dwarfed by the consumption in operations. The 10 kwh of manufacturing energy for LEDs and CFLs is barely noticeable compared to 3,290 kwh of energy use from incandescent light bulbs over the life of one LED.

What is the Color of Light?

SunLightbulb illustration by John Dolley

Illustration by John Dolley

Humankind evolved with sunlight as its light source. In a society that spends more than 90% of its time indoors, the absence of sunlight can have serious health, psychological, and aesthetic repercussions. There are 3 characteristics of light that need to be considered for indoor lamps.

1. Does the light source have good color discrimination? Poor light quality allows minimal ability for people to distinguish between shades and colors. Extremely poor quality light allows no ability at all. Light sources are rated by a standard called “Color Rendering Index,” or CRI. Sunlight has a CRI of 100. One of the few good things about incandescent bulbs is that they have a CRI of 99-100. Standard CFLs have a CRI of around 82, and most LEDs manufactured at this time have a CRI of around 80.

Scientific studies have shown that less light is needed with the use of high-CRI lamps. Some European countries actually suggest or mandate high-CRI lamps in building codes.

With some exceptions, high-CRI compact fluorescents emit less visible light (lumens) than their conventional counterparts. This may not matter for color-related tasks, but black-and-white tasks such as reading may be of concern in some situations.

2. Does the light resemble the sun’s color? Most people think sunlight is yellow. But it is actually bluish-white. Look at light coming through a north window at noon and you will see this yourself. Light colors are measured by how closely they match glowing heated metal. An incandescent filament glows at 2,700-3,000 degrees Kelvin. Sunlight matches metal heated to 5,000-6,500 degrees Kelvin.

Some people do not like “daylight” or “natural spectrum” lamps because they do not resemble incandescent color. Incandescent light bulbs have a reddish-yellow glow that resembles gaslights, candles, oil lamps, and torches that societies historically became accustomed to for artificial light sources. This standard of normal was dictated by the technology available, which has improved in the last few decades as bulbs employed phosphor coatings that better resembled sunlight.

3. Does the light emit ultraviolet radiation? Sunlight emits UV radiation, which is essential for health. Calciferol, otherwise known as Vitamin D, is not a vitamin at all, but a hormone produced when UV radiation touches the skin. It is essential for calcium absorption and proper metabolism.

This article could identify only two commercial products that emit useful UV radiation. They carry a premium above the extra premium that already exists for high-CRI bulbs that do not emit UV. If you are considering their purchase, keep 2 things in mind. First, the average person under these lamps for 8 hours a day will receive the equivalent of about 6 minutes of full sunshine. Some people might decide it is cheaper to just go outside for a few minutes instead of paying the lamp’s premium. Others who have limited time may find the cost worth it.

Second, most UV radiation will not penetrate the glass or plastic lens on enclosed fixtures. To get the benefit of these lamps, you need an open fixture.

List of high-CRI lamps

Halogen lamps are a variation of incandescent and have the same high CRI as conventional bulbs. There are CFLs that have both high CRIs and daylight color temperatures in the same bulb. LEDs are also beginning to be produced with high-CRI and daylight color temperature models, though as of press time, no product had both at once. Chart 4 lists some of these high-CRI conventional (A19) CFLs. Chart 5 lists high-CRI linear fluorescent replacement products. Chart 6 lists the few high-CRI LEDs on the market now. The number of products will likely grow as the technology becomes more common. It should be noted that there are also good color quality lamps for downlights and spotlights.

Chart 4: Full-Spectrum Compact Fluorescent Lamps
(5,000-6,500 K, CRI 90+)
CompanyPurchase OutletContactProducts
Alzo Digital (800) 582-7009 Various sizes
EiKO (800) 852-2217 30-watts
Full Spectrum Solutions (888) 574-7014 Various sizes
H & H Industries (800) 637-3853 Various sizes, high brightness
NaturesSunlite (888) 900-6830 Various sizes, UV-emitting
Ottlite Various locations Various sizes
Vitalite (888) 900-6830 Various sizes, UV-emitting
Chart 5: Fluorescent Tubes With CRI 90+ and Color Temperature Above 5,000˚ K
Full Spectrum Solutions BlueMax GE
Chroma 50 Sunshine ShowBiz
H & H Industries Vi-Tec 93+ Osram Sylvania
Daylight Full Spectrum Design 50
NaturesSunlite Philips TL950
Daylight Deluxe Color Tone 50 Color Tone 75
Natural Supreme Natural Sunshine Ushio
Ultra 5000 (T10) Westinghouse Realite
Chart 6: LEDS With CRI 90+ (Surveyed 12/12/12)
Brand Model Number Equivalent Incandescent Wattage New Wattage Company Web site
LEDnovation LEDH-A19-60-1-27D-IO 60 9.4
LEDnovation LEDH-A19-75-1-27D-IO 75 13.7
LEDnovation LEDH-A19-100-1-27D-IO 100 19
Philips 423244 60 10
Sylvania 12A19/DIM/F/927 60 12

Are there hazardous materials in these CFL lamps?

Most electric light sources contain toxins. Many conventional incandescents use lead, both in the solder that seals the bulb at the bottom and in the optical glass itself. CFLs contain mercury in vapor form and/or in the phosphor that coats the glass. LEDs and CFLs employ heavy metals in the electronic circuitry that controls them.

The light family of most concern is CFLs. The amount of mercury in CFLs is relatively small. New CFLs contain 0.4 to 4 milligrams. This is much smaller than other mercury-containing domestic products such as thermometers (which use 500-1,000 milligrams). On a lifecycle basis, the total mercury in CFLs is also much smaller than the mercury emitted by coal-fired electric stations to supply incandescent lighting. A 60-watt incandescent bulb will cause 5.5 grams of mercury emissions over its lifetime. A 13-watt CFL, producing the same amount of light, will only cause about 1.6 grams to be emitted under worse-case conditions such as lamp breakage in a solid waste landfill.
However small the amount of mercury is though, it is a toxin that must be respected. If the CFL breaks, the mercury vapor can escape into the house, and the mercury-coated glass needs to be removed with care.

If breakage occurs, consider the following clean-up practices.

1.Ventilate the room for 15 minutes. Turn off Heating, Cooling and Ventilation equipment while clean-up is occurring. If conditions permit, you might consider ventilation or HVAC shut-off for several hours after clean-up.
2. Wear cleaning gloves when removing the glass. Pick up or sweep up glass by hand, remove pieces with tape, or with a wet paper towel.
3. Do not use a vacuum cleaner for any type of glass clean-up, as it may distribute tiny glass particles in the air.
4. Put CFL pieces in a closed glass jar, or in a double plastic bag, until you can dispose of it properly. If possible, store the jar or bag in garage or storage shed outside the house.
5. For more detailed cleaning advice, see:

Some or most clean-up problems can be avoided by buying shatter-resistant CFL models, or models that have a polycarbonate lense over the glass. Also, try to insert CFLs in the socket by holding their base, not the glass.

Where Can I Recycle CFLs?

See the Web site for locations in your area.​

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