CFL's are fairly old hat now - but I was wondering of anyone had any total life cycle costs for these ? If we include the energy used in manufacture, transport and disposal - and also the fact that for 20% of the year in teh UK the side effect heat that comes from a standard filament bulb is actualy useful in heating a well insulated and thermostat controlled building .
+ there is mercury in CFL's that really should be disposed of properly .
Could LED bulbs be the answer ? Any environmental side effects to their manufacture and transport ?
Paul in Montreal
posted on 19-06-06
David,
if you think there are environmental issues to CFLs (mercury etc.) these pale in comparison with the extremely nasty chemicals used in any electronics manufacture (arsenic, boron, phosphorous, gallium etc.) Semiconductor plants have been implicated in ground water contamination in many locations in California - though most manufacturing is in Southeast Asia now.
In terms of energy, CFLs are still significantly more efficient than even the most efficient LEDs. Whilst LEDs are improving, they're not there yet - at least not in the wavelengths of light that are useful for us (infra red LEDs are more efficient than CFLs).
All that said, there is a good chance that LEDs will continue to improve in efficiency and will overtake CFLs. One current problem with LEDs is that efficiency and useful lifespan are linked - if you try to increase the light output, the LED's material does break down over time (especially if the junction gets too hot) and so the light output diminishes with time. Current state of the art gives useful lifes of about 100,000 hours (approximately 10 years).
I'm sure that LEDs will become the dominant form of lighting in the future but, at the moment, CFLs are more environmentally friendly in terms of light output versus total energy input over their working life.
Paul.
Tony
posted on 19-06-06
David, re 20% of the year.... Do you not mean 80%?
I do not like low energy light bulbs apart from the mercury they also contain other heavy metals. The light they give out is not nearly so nice as incandescent light. They don't save as much as people claim as, as you mention the heat lost is usefull heat a lot of the time. I would use them outside or in sheds or garages. If the cost of changing the bulb is included then all buisness use would have to go for low energy but domestically where we change our own bulbs and where the usefull heat loss is used there is not much of a case for using them.
David Morton
posted on 19-06-06
Thanks Tony,
20% was an optimistic assesment of the British climate ! Point was that
Incandescent bulbs are actualy 100% efficient at converting electricity into light and heat. At some points in the year in a cold or temperate climate, the heat is actualy useful.
So any calculation on efficicency for CFL should take into account the difference in efficiency between heat generated by an incandescent bulb and heat generated by another heat source - say natural gas for the 20% - 80% of the year when the heat is actualy of use.
All the calcs for CFL's I have seen assume that no heat is actualy required - only light
I suppose in hot countries this may be the case for most of the time.
I also agree with you bulb changing cost comment - for business light bulb change costs are significant
David
Biff
posted on 19-06-06
In the context of UK energy supplies, we have a particular problem with our electricity generating capacity. Last winter we only escaped the lights going out on a couple of days by shutting down some large industrial gas users and allowing the daily traded spot price for gas to quadruple, forcing other industries to cut demand. This allowed the gas power stations to keep going. But only just. The problem will repeat next winter, is temporarily eased with the supply from Norway coming on stream but then becomes dependant on competing with the rest of Europe and China for Russian gas. As the ageing nuclear fleet go out of service the problem worsens. The slow investment in renewables means that we will have no choice but to reduce electricity consumption, either voluntarily by switching to CFLs and a hundred and one other methods, or forcibly with power cuts. Saying that the heat from incandescent bulbs usefully mitigates there use denies the proverbial elephant.
Paul Teather
posted on 19-06-06
I have performed some calculations based on a complte life cycle and can also allow for some psychology "Leave it on its cheap to run".
Replacing a hall bulbs (60W) with Compact flourescents(15W):
Note that the 15W bulbs will be brighter - If somebody remarks I tell them energy efficient bulbs are brighter, so they are more likely to use them!
Allowing a passive gain effectiveness (usable heat) of 25% and gas heating then a contribution of 118 kwh is lost at £2.36
Net Saving : £34.39
Payback - 7 months (typical)
CO2 saving 41Kg per year
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Note: for building regulations this needs to be a 2 or 4 pin fitting and hecne will cost more.
Other bulb types:
CF exterior lights are a huge saving
LEDS are not ready yet (maybe 2-5 years)
Cold Cathode bulbs are very good as halogen bulb replacements, but expensive (£15 per bulb) and so take longer to pay back. But good over a few years and good on CO2.
If you do not mind a larger light fitting Halogen bulbs can be replaced with R50/R80 reflecting compact flourescents.
A Halogen lights runs at approximately 20 lumens per watt.
CF are approx 60 lumens/watts
So replace a 50W Halogen with 15W of CF. Two hours per day should repay in less than two years.
Note : Daylight quality flourescent tubes (T8)are the most efficient domestic lighting available (80 lumens/Watt), especialy in a reflector housing
