How long do energy saving light bulbs take to warm up?

Energy saving lights are commonly either CFL’s or LED’s .  The warm up time between these two types of lamps varies dramatically.

CFL warm up

The CFL bulbs need a few minutes to reach the optimal brightness because when the bulb is cold the mercury vapour is not fully ionized and the phosphor coating takes time to reach maximum efficiency.  When switched on the CFL will light up to 60-80% of its brightness almost immediately and then over the next couple of minutes the light output will gradually increase until it reaches its maximum operating temperature.  Cold environments such as garages will increase the warm up time.

CFL’s are more energy efficient than incandescent bulbs but the delayed warm up time and their mercury content has led to them now being replaced by LED’s.

Light emitting diodes (LED’s)

LED’s produce light when an electrical current passes through a semiconductor material which releases energy in the form of light and is instantaneous.

LED warm up

Led bulbs do not have a warm up time, when you turn them on it achieves 100% of brightness instantly. CFL’s can have slight differing in colour as they warm up but LED’s maintain the same colour throughout.

Do energy saving light bulbs get hot?

All light bulbs produce some varying amounts of heat but it differs significantly between the types of bulbs.

CFL’s are cooler to touch than incandescent bulbs but they do produce heat through the ballast but it is not normally a concern.

LED’s produce very little heat as they convert the majority of the energy used into light and they are fitted with heat sinks which draws heat away from the LED chips.  The glass of the led bulb stays relatively cool but the base or heat sink can feel warm or even hot after the bulb has been on for a while, this is intentional as it signifies the bulb is working correctly.