Light sources

Fluorescent lamps

• An excellent general luminaire for indoor use but not ideal for outdoor areas
• Various shapes, sizes, and efficacies
• High efficacy (>100 lm/W)
• Wide colour range (R_a > 90)
• The need for an electronic ballast for control (control range 1–100%)
• A long useful life

Compact fluorescent lamps (energy-saving lamps)

• A high level of illumination for a small amount of energy
• A good light source for general lighting and for spaces that require a high level of illumination
• A light source that doesn’t withstand being turned on and off frequently 
• Lighting that comes into its own in outdoor luminaires (not all models; also, luminaire protection must be taken into account)
• Efficacy of 50–80 lm/W
• Full brightness only after a warm-up period
• A solution that usually is not dimmable

Halogen lamps

• Use for spotlighting and outdoor lighting
• Easy control (with several possible control methods and a control range of 1–100%)
• Good colour rendering 
• Good light optics
• Small luminaires
• Availability with several lamp bases (GU10, PARxx, and bi-pin)
• Surface temperatures possibly reaching high levels
• In control, a need for compatibility between the transformer and controller
• A high illuminance value (glare) of the filament

Metal-halide lamps

• Suitability for high spaces and outdoor lighting
• High efficacy, 75–120 lm/W
• Good light optics
• Good colour rendering (R_a up to 90)
• A long useful life
• A long warm-up period
• Need for a starter
• Dimming that affects the light colour
• Dimmability for only the non-compensated lamps (control range 50–100%)
• A decreased service life when dimming is used (not recommended)
• The need for lamps to be turned on at full efficacy (once they have been on for 10 minutes, they can be dimmed in stages)

High-pressure sodium lamps

• Suitability for road and street lighting 
• White SON also for indoor lighting
• Utility in illuminating yellow, red, and brown tones
• Need for a starter
• High efficacy, 60–150 lm/W
• A long useful life
• High luminous flux values
• Restricted colour rendering
• Control not recommended (control range 50–100%, for short periods 30%)
• Dimmability for only the non-compensated lamps (dimming shortens the service life)
• The need for lamps to be turned on at full efficacy (once they have been on for 10 minutes, they can be dimmed in stages)
• A long warm-up period

Low-pressure sodium lamps

• Road and street lighting as the most common application
• High efficacy, up to 200 lm/W
• Need for a starter
• Poor colour rendering properties
• A short service life
• Lack of dimmability
• A type that is being replaced with high-pressure sodium lights on motorways and in some other applications

High-pressure mercury lamps

• Suitability for outdoor lighting in parks
• No need for a starter
• Poor efficacy values (40–60 lm/W)
• Control not recommended (control range 50–100%)
• The need for lamps to be turned on at full efficacy (once they have been on for 10 minutes, they can be dimmed in stages) 
• A solution that was withdrawn from the market by 2015 because of its low efficacy (under the Ecodesign Directive)

LED

• A long service life, up to 50,000 hours
• Low energy consumption
• High efficacy, 75–113 lm/W (and still improving)
• Easy control and dimming (note: conventional controllers can be used)
• No changes in service life with the number of times the lamp is turned on
• Still a relatively expensive solution
• Sensitivity to high temperatures (this affects the service life and reduces luminous flux)
• The possibility of glare, since this is a small and bright source of light

Induction lamps

• Suitability for outdoor lighting and high spaces
• Good efficacy, up to 70 lm/W
• A long service life, up to 100,000 hours
• No changes in service life with the number of times the lamp is turned on