"Negawatts" - Preparing for Your New Electric Car

drees said:

While an incandescent bulb typically lasts about 1000 hours at most, your typical CFL is rated for between 6000-15000 hours.

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Wow, I've never seen a CFL last anywhere close to 6000 hours. Here at the office they tend to last around 1000 hours, 1500 if it's feeling special...

After all that, I do admit that I use CFLs and not LEDs (with the exception of a little experimenting with one fixture). The reason being, I can buy CFLs for $2 and most LEDs are either extremely expensive or not nearly bright enough. I'm careful not to drop the bulb and break it, and now that I know about the mercury content I plan to dispose of them properly when they burn out, so for me CFLs are environmentally just fine, and LEDs are not yet cost-effective. But LEDs are getting brighter and more efficient all the time, so it won't be long before they really take over.

DarkStar said:

drees said:

While an incandescent bulb typically lasts about 1000 hours at most, your typical CFL is rated for between 6000-15000 hours.

Click to expand...

Wow, I've never seen a CFL last anywhere close to 6000 hours. Here at the office they tend to last around 1000 hours, 1500 if it's feeling special...

Click to expand...

It depends on the application. CFL bulbs are rated bare bulb in free airspace at a steady room temperature, constantly on.

Flourescent lights use electrically charged vaporized mercury that produces UV light, which hits phosphors to give off visible light. Charging the mercury to turn the light on puts great stress on the bulb. If you switch them on for a second, then off constantly, CFL's can last less than a day- occupancy sensors can dramatically cut lifespan. Put them in a recessed fixture (if they are even rated for that usage- not all are), and it cuts lifespan in half- even worse if you have sealed recessed fixtures due to heat management.

LED's are light emitting diodes (solid state switches that give off light) and are very happy to be repeatedly switched on and off. In video projectors, they are actually switched on and off hundreds of times per second. In the case of quality LED lighting fixtures, like the ones from CREE- they are designed and rated for the end-use application.

If you are using fixture where the bulb is in free airspace, the light is intended to radiate in all directions from the bulb, it is on for long periods at a time and you aren't worried about mercury, CFL is fine. But for directional applications, recessed applications, or applications where they are constantly being switched on and off, not so much. For example, if you are using recessed fixturers, the CLF bulbs do not last long, are often hard to take out and can break easily. In our office, switching from incandescant to CFL meant we ended up changing bulbs every quarter, rather than every month. People looking at manufacturer's ratings on CFL's aren't taking into account how they are rated or real world usage.

LED comes out far ahead if used in many applications, especially when taking labor costs into account. Dimmability and use with occupancy sensors can further add to energy savings. Especially if the location is hard to reach, LED's make perfect financial and practical sense.