The compact fluorescent lamps (CFL) with integral control gear are a perfect solution for direct replacement of General Lighting Service lamps. The compact fluorescent lamps have a lower running cost because of their greater efficiency but higher initial cost. The cost benefit analysis therefore depends on the hours of use of the lamp.

In some case, particularly the decorative lamps, the appearance, physical dimensions or weight of the compact fluorescent lamps may be unsuitable.

Because compact fluorescent lamps are not point sources (like incandescent lamps), CFLs are not as effective in projecting light over distance. The light output from CFLs is much more diffuse; lumens easily stray from the intended target in directional lighting applications. As such, these lamps may not be suitable in high ceiling downlighting applications or where tight control of beam spread is necessary.

Manufacturers do not recommend using compact fluorescent lamps with integral control gear with a dimmer or a timer.

So that lamp size and weight can be kept to a minimum, some of these lamps have a relatively poor power factor, an important consideration when a large number are likely to be used in a building.

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Because induction lamps are not point sources (like incandescent lamps), they are not as effective in projecting light over distance. The light output from induction lamps is much more diffuse. As such, these lamps may not be suitable where tight control of beam spread is necessary.

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Exit signs: Of the retrofit options for incandescent lamps in exit signs, light-emitting diode (LED) sources are the most cost-effective. Combined with the extremely long rated life of LED sources, this option is an economical retrofit based on life cycle cost. The LED retrofit consists of a pair of LED strips that follow the side panels of the exit sign enclosure. Reflective film or a diffusing panel is used to direct the LED output to the face of the sign. Check with local building codes for accepted emergency exit sign illuminance and retrofit sources.

Traffic lights: Traffic signal operators are best served by the operation of maintenance-free and safe lights at low cost. For this reason incandescent bulb lamps become more and more inappropriate for this application. They only last a year (at best) and are unreliable. Maintenance must be carried out regularly. Hydraulic cranes have to be used and roads have to be blocked in order to replace bulbs at the expense of time, money and traffic jams. The replacement of a single lamp is even more expensive. LEDs do not have these disadvantages: they are reliable, last much longer and have low expenditure of energy.
Incandescent bulbs (including Krypton and halogen lamps) are not readily interchangeable with LEDs - the shape is different and the lens has to be replaced. In traffic lights, lamps are constantly monitored to check whether a lamp is operating properly. For this purpose the controller monitors the current. However, LEDs use so little energy that it is hard to detect any current. The solution here is to decrease the voltage of the power supply from 230V to a lower voltage, for example 48V, and by doing so increasing the current. This makes it easier to measure the current.
LED lamps in enclosed housing have been recommended. An LED signal lamp with high-quality LEDs and electronics is energy-efficient. Lamps of poorer quality have cheaper LEDs and electronics that use more energy and convert more electrical energy into heat. These lamps are not supplied in enclosed housings as the temperature would rise too much. A lamp in an enclosed housing assures built-in quality. Moreover, the quality check is easier to perform and transport damage is minimised. When the lamps of a classic signal lamp are replaced, the lens is always cleaned on both sides. This is not necessary for enclosed LED signal lamps as they do not attract dirt on the inside. LED signal lamps are equipped with a small number (<18) of high-power LEDs or with a high number of 5mm LEDs. Enclosed signal lamps are interchangeable, which makes it possible to benefit from both types of lamps.

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Some tungsten halogen line-voltage single-ended lamps are designed as direct replacements for standard tungsten display lamps. In particular, PAR halogen lamps are available which can be used as direct replacements for incandescent PAR lamps. At present the increased cost of these is not recovered by the energy savings during their life, but this would change if the initial cost were to decrease. Consider such replacement if the replacement with a compact fluorescent lamp (better efficacy) is not possible and check if the replacement is allowed for your type of luminaire.

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A direct substitution of 38 mm diameter lamps by 26 mm lamps can be made to existing luminaires with switch-start control gear, but it cannot be made with other types of conventional control gear (e.g. rapid-start). It is also possible in some starterless circuits, if in doubt, consult the manufacturer.

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High pressure sodium lamps offer an energy efficient and cost-effective option if a replacement or refurbishment programme is being considered. These lamps provide an inexpensive means for significantly improving light output (by 76-106%) while saving 6-14% in energy consumption in existing mercury vapor luminaires.

In some instances it is possible to replace mercury lamps directly with plug-in sodium lamps. Verify that your existing mercury ballasts are compatible. Check also the Colour Rendering Index of the plug-in sodium lamp. Some manufacturers only commercialise plug-in lamps with very poor colour rendition properties which might not be suitable for your application. Conduct a trial installation to find out if resultant light levels and visual comfort will be acceptable.

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Metal halide lamps offer an energy efficient and cost-effective option if a replacement or refurbishment programme is being considered. In some instances it is possible to replace mercury lamps directly with plug-in metal halide lamps. Check if the available wattages of the plug-in metal halide lamps are suitable for your application. Consider such replacement if the replacement with sodium lamps (better efficacy) is not possible.

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