The primary purposes of Compact Fluorescent Lamp design are high electrical efficiency and durability. However, there are some other areas of Compact Fluorescent Lamp design and operation that are problematic:

    * Quality of light: A phosphor emits light in a narrow frequency range, unlike an incandescent filament, which emits the full spectrum, though not all colors equally, of visible light. A mix of phosphors gives a good approximation of daylight or incandescent light can be reached. However, every extra phosphor added to the coating mix causes a loss of efficiency and increased cost. Good quality consumer Compact Fluorescent Lamps use three or four phosphors to achieve a 'white' light with a Color Rendering Index (CRI) of around 80, where 100 represents the appearance of colors under daylight or a blackbody (depending on the correlated color temperature).

    * Size: Compact Fluorescent Lamp light output is roughly proportional to phosphor surface area, and high output Compact Fluorescent Lamps are often larger than their incandescent equivalents. This means that the Compact Fluorescent Lamp may not fit well in existing light fixtures.

    * End of life: A detailed description of the failure modes of fluorescent lamps is given in the Fluorescent lamp article. Additionally, the electronic ballast may fail since it has a number of component parts; such failures may be accompanied by discoloration or distortion of the ballast enclosure, odors, or smoke. The lamps are internally protected and are meant to fail safely at the end of their lives. Industry associations are working toward advising consumers of the different failure mode of Compact Fluorescent Lamps compared to incandescent lamps, and to develop lamps with inoffensive failure modes.

    * Dimming: Some lamps are labelled for Dimming control. Using regular Compact Fluorescent Lamps with a dimmer can shorten bulb life and will void the warranty of certain manufacturers. According to BC Hydro and Environmental Defense, dimmable screw-in fluorescent lamps are now available. Westinghouse claims to have released a dimmer that can dim non-dimmable Compact Fluorescent Lamps. The dimming range of Compact Fluorescent Lamps is usually between 20% and 90%. Dimmable Compact Fluorescent Lamps are not a 100% replacement for incandescent fixtures that are dimmed for "mood scenes" such as wall sconces in a dining area. Below the 20% limit, the lamp remain at the approximate 20% level, in other cases it may flicker or the starter circuitry may stop and restart. Above the 80% dim limit, the bulb will generally glow at 100% brightness. Dimmable Compact Fluorescent Lamps have a higher purchase cost than standard Compact Fluorescent Lamps due to the additional circuitry required for dimming. A further limitation is that multiple dimmable Compact Fluorescent Lamps on the same dimmer switch may not appear to be at the same brightness level.

    * Heat: Compact Fluorescent Lamps get warm in operation, so some Compact Fluorescent Lamps are labelled not to be run base up, since heat will shorten the ballast's lifetime. Some Compact Fluorescent Lamps are unsuitable for use in pendant lamps and especially unsuitable for recessed lighting fixtures. Compact Fluorescent Lamps intended for use in such fixtures are available.[55] Current recommendations for fully enclosed, unventilated light fixtures (such as those recessed into insulated ceilings), are either to use 'reflector Compact Fluorescent Lamps' (R-Compact Fluorescent Lamp) or to replace such fixtures with those designed for Compact Fluorescent Lamps.

    * Large deployments of Compact Fluorescent Lamps require specialized electronics with low levels of electronic distortion to avoid disturbing the electricity supply; unless corrected, electronic ballasts have a low power factor due to their rectifier input stage. This is usually not a problem with home use because of the few lamps deployed per site and because current drain is less than that of the replaced incandescent lamps.

    * Time to achieve full brightness: Compact fluorescent lamps may provide as little as 50-80% of their rated light output at initial switch on and can take up to three minutes to warm up, and color cast may be slightly different immediately after being turned on. This compares to around 0.1 seconds for incandescent lamps. In practice, this varies between brands/types. It is more of a problem with older lamps, 'warm (color) tone' lamps and at low ambient temperatures.

    * Infrared signals: Electronic devices operated by infrared remote control can interpret the infrared light emitted by Compact Fluorescent Lamps as a signal limiting the use of Compact Fluorescent Lamps near televisions, radios, remote controls, or mobile phones.

    * Audible noise: Compact Fluorescent Lamps, much as other fluorescent lights, may emit a buzzing sound, where incandescents do not. Such sounds are particularly noticeable in quiet rooms, and can be annoying under these circumstances.Newer compact fluorescent light bulbs are nearly noiseless, but some poorly made Compact Fluorescent Lamps may still emit a buzzing sound.

    * Use with timers: Electronic (but not mechanical) timers can interfere with the electronic ballast in Compact Fluorescent Lamps and can shorten their lifespan.

    * Fire hazard: Inferior quality electronic components used in some Compact Fluorescent Lamps can cause excessive heat or fire.

    * Outdoor use: Compact Fluorescent Lamps that are not designed for outdoor use may perform poorly in cold weather; Compact Fluorescent Lamps are available with cold-weather ballasts, which may be rated to as low as -23°C (-10°F).Standard compact fluorescents will fail to operate at low temperatures. Light output drops at low temperatures.

    * Differences among manufacturers: There are large differences among quality of light, cost, and turn-on time among different manufacturers, even for lamps that appear identical and have the same color temperature.

    * Fluorescent lamps get dimmer over their lifetime,so what starts out as an adequate luminosity may become inadequate. In one test by the US Department of Energy of 'Energy Star' products in 2003-4, one quarter of tested Compact Fluorescent Lamps no longer met their rated output after 40% of their rated service life.