Light bulbs last updated: 13/02/2014
Light bulbs are divided by type into CFL and LED lamps, with the following sub-categories:
- E27 (large screw) cap
- B22 (bayonet) cap
- E14 (small screw) cap
In order to be featured on Top10, light bulb models must comply with European Commission Directive 2009/125/EC with regard to energy labelling of directional lamps, light emitting diode lamps and related equipment, as well as meeting the following criteria:
- Energy efficiency class A
- Luminous efficacy:
- Sticks E27/B22/E14 and Bulbs E27/B22: minimum. 50 lm/W, if length > 105 mm
- Sticks E27/B22/E14 and Bulbs E27/B22: minimum 40 lm/W, if length < 105 mm
- Bulbs E14 and Candles E27/B22/E14: minimum 40 lm/W
- Life time: mínimum 12,000 hours
- Switching cycles: mínimum 50,000
- Warm-up time: maximum 60 seconds
- Be for domestic use
- Luminous efficacy:
- Up to 300 lm: minimum of 45 lm/W
- 300 to 470 lm: minimum 50 lm/W
- Above 600 lm: minimum 60 lm/W
- Life time: minimum 20,000 hours
- Switching cycles: minimum 50,000
- Colour Rendering Index: minimum 80
Inefficient model selection
The “inefficient model” is an anonymised halogen retrofit bulb equivalent to the most common output in each sub-category. This allows comparison with the least efficient technology available.
Annual energy consumption: the energy consumption, in kWh, per year based on 1,000 hours of use.
Annual running cost: the annual running cost in electricity for the product based on the quoted annual energy consumption and an electricity cost of 14.5p/kWh.
Average retail price: the average market price of the product determined by checking prices for the specific model advertised by at least three retail websites.
Colour temperature: the light colour appearance of a lamp can be defined in terms of its colour temperature in degrees Kelvin (K). There are three main colour groups: warm whites < 3300 K; neutral whites 3300 K - 5000 K and daylight whites > 5000 K.
Colour of light: the colour group of the bulb as defined above.
Dimensions: the unpacked dimensions of the product in mm.
Dimmable: whether the bulb can be dimmed using a standard lightswitch or dimmer switch.
Energy label: the energy efficiency class according to the EU Energy Label. The classes range from A++ (most efficient) to E (least efficient).
GLS wattage equivalent: the wattage of an equivalent GLS (incandescent) bulb.
Life expectancy (hours): the number of hours the bulb is expected to last, defined as the point at which 50% of bulbs will have failed.
Luminous efficacy: the efficiency of the bulb in light output (lumens) per unit of power (watts). This is used to determine a lamp’s inclusion in Top10 and to rank the featured models.
Shape: the form of the lamp. Including bulb, candle, globe, golf ball, spiral and stick types.
Switching cycles: the number of times the lamp can be switched on and off before failure. According to Regulation (EC) No 244/2009, a switching cycle consist of a period comprising 1 minute on and 3 minutes off.
Warm-up time: the maximum time by which the bulb will have reached 60% of its maximum output.
Wattage: the rated power consumption of the lamp in Watts.