What Size of CFL Should I Use to Replace An Incandescent Bulb?
First, let's compare a standard 60 watt bulb with an "equivalent" CFL replacement bulb.

 

Type	Watts	Lumens	Color Temp.	CRI	Life (hrs)
Incandescent	60	830	2,800°K	100	1,500
CFL	13	900	2,700°K	84	10,000

 

The higher the lumen rating, the greater the light output. For more information on lumens go to the ENERGY STAR website.  Notice that you get the same or more light output (lumens) with a 78% energy reduction and over six times the rated life! The equivalent lumen output CFL wattage for incandescent replacement (roughly 25%) is shown in the following table.

 

CFL Replacement Wattages
Incandescent	CFL
200	55
150	42
100	23-26
75	20
60	13-15
40	9-11

 

How Can I Justify Paying 5X the Price for a CFL?
Actually, the cost of operation easily dwarfs the purchase price. For example, let's compare a 60 watt incandescent bulb that costs $0.50 each to a 13 watt CFL that costs $2.50 each in bulk. The electricity cost to operate those lights is calculated as follows:

Electricity cost = hours of operation x (wattage ÷ 1,000) x $/kWh

Lets assume that the lights operate 12 hours per day year round and that the cost of electricity is $0.085/kWh.

Electricity cost (Incandescent) = 4,380 hrs x 0.06 kW x $0.085/kWh = $22.34

Electricity cost (CFL) = 4,380 hrs x 0.013 kW x $0.085/kWh = $4.84

The savings from changing to a CFL is about $17.50 annually, which more than recovers the difference in purchase price ($2.00). Because the CFL is rated to last roughly 10,000 hours, there is an additional saving from not having to replace the incandescent bulb five times (an additional $2.50 saving).

Can CFLs Be Used in Ceiling Fans?
A ceiling fan application can exhibit several possible CFL failure modes: vibration, low voltage, overheating, frequent switching on/off and the possibility of being wired to a dimmable switch.

At first blush, one would think that CFLs would handle vibration just fine due to the absence of a filament. However, GE Consumer & Industrial Lighting's FAQs web page listed this response to the same question:

5. Can I use a CFL in applications involving vibration such as a ceiling fan or garage door opener?

Currently it is not recommended to use CFLs in vibrating environments. Vibration can cause the electronics in the CFL to fail.

On the other hand, GE recommends its FLE11 globe CFL for use in a ceiling fan. In addition, we find no such warnings from other lamp manufacturers such as Philips or Osram Sylvania. Furthermore, many new electronic ballasts now come with built-in filtering and protection circuits that are improvements over the less expensive designs.

Do CFLs Quickly Burn Out in Recessed Lights?
Some fluorescent ballasts are unreliable in ambient temperatures much over 120°F (50°C). This is sometimes a problem in enclosed or recessed ceiling fixtures if heat in the fixture builds up. The Rensselaer Polytechnic Institute Lighting Research Center publishes a newsletter, Lighting Answers. An article on high-wattage compact fluorescent lamps (HW-CFLs) showed the temperature increased from an average of about 25°C (77°F) to 40°–60°C (100°–140°F) in enclosed aluminum reflectors and prismatic refractors. The temperature rise in open reflectors/refractors was much smaller. These high-wattage CFLs were rated at 55–105 watts.

In 2002, Pacific Northwest National Laboratories (PNNL) completed technical and market research on reflector CFLs (R-CFLs) in the 12–20 watt range and identified a number of challenges to increased use of R-CFLs installed in insulated, ceiling-rated, airtight (ICAT) recessed can housings:

• Delivered light output. Total light output for R-CFLs was often significantly less than their incandescent counterparts, and R-CFLs installed in high ambient temperature environments generally produced lower light levels, compared to CFLs installed in "open" fixtures at room temperature.
• Longevity. Operating life was often much shorter than the manufacturer rated life when installed in insulated ceiling environments. Operating temperature was often above manufacturer guidelines when operated in an ICAT can.

Note that the PNNL R-CFLs were not totally enclosed. The housings were open on one end but not vented, thus the categorization as "airtight" to prevent loss of conditioned air into unconditioned spaces above, such as attics.

Sylvania CFL Reflector

In a follow-up report, Philips Lighting Company R-CFLs Prove They Can Take the Heat, the Philips SLS/R40 20 watt and the EL/A BR30 16 watt Reflector Flood, which are part of the Philips® Marathon™ line, met the DOE's stringent performance criteria for its R-CFL project, including ENERGY STAR® certification and a minimum of 6,000 hours of elevated temperature life testing. Manufacturers now have specially designed recessed housings for fluorescent lighting.

 

Can I Use a CFL With a Dimmer Switch?
GE's FAQ web page also addresses switching of lights and dimmable switches.

3. Can I use a compact fluorescent light bulb with a dimmer switch?

To use a compact fluorescent bulb on a dimmer switch, you must buy a bulb that's specifically made to work with dimmers (check the package). GE makes a dimming compact fluorescent light bulb (called the GE Longlife Plus Soft White Energy Saving Bulb) that is specially designed for use with dimming switches. We don't recommend using regular compact fluorescent bulbs with dimming switches, since this can shorten bulb life. (Using a regular compact fluorescent bulb with a dimmer will also nullify the bulb's warranty.)

4. Can I use a CFL in applications where I will be turning the lights on/off frequently?

Compact fluorescent light bulbs work best if they are left on for over fifteen minutes each time they are turned on. These types of lamps can take up to three minutes to warm-up. Warm-up will probably not be noticeable from a user standpoint, but the lamp needs to warm up in order to reach the point of most efficient operation. Frequently switching them on and off will shorten the life of the product. If the life of the lamp is shortened significantly, you will not reap the financial benefits (includes energy & life of lamp), that are common to CFL lamps.

What Should I Do If a CFL Breaks?
Because there is such a small amount of mercury in CFLs, your greatest risk if a bulb breaks is getting cut from glass shards. Research indicates that there is no immediate health risk to you or your family should a bulb break and it’s cleaned up properly. You can minimize any risks by following these proper clean-up and disposal guidelines:

1. Sweep up—don’t vacuum—all of the glass fragments and fine particles.
2. Place broken pieces in a sealed plastic bag and wipe the area with a damp paper towel to pick up any stray shards of glass or fine particles. Put the used towel in the plastic bag as well.
3. If weather permits, open windows to allow the room to ventilate.

The previous procedure on proper disposal approaches is compiled from an ENERGY STAR® fact sheet on CFLs. LampRecycle.org has a directory of state regulations governing lamp disposal. The website www.earth911.org offers disposal options by using your zip code, or call 1-877-EARTH911 for local disposal options.

What are the ENERGY STAR®  requirements for CFLs?
The power factor (PF) of today's ENERGY STAR rated CFLs must be 0.50 or greater (average of ten samples). Power Factor is a measure of how effectively a device converts input current and voltage into useful electric power. Many CFLs have a 0.6 PF rating. Look for the HPF (High Power Factor) designation in CFL nomenclature such as the CF15/DQ/27K/HPF bulbs from Genesis Lamp. ENERGY STAR rated CFL lumen maintenance must be greater than 90.0% of initial (100-hour) lumen output @ 1,000 hours of rated life and greater than 80.0% of initial lumen output at 40% of rated life (e.g., @ 4,000 hours for a 10,000 hour CFL). The Color Rendering Index (CRI) must be greater than 80. This compares to lumen maintenance of a little over 90% at 40% of rated life and CRI in the mid 80's for fluorescent tube lamps.

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