Bought one of the new mini LED bulbs they now sell in Japan, and replaced the mini-krypton incandescent bulb in a downlight.
LEDs are still expensive. Are they worth it? Depends on where you use them. Let's take a look (video, 2 minutes) and calculate the time to break-even, below.
The Light, the Energy
See for yourself.
After 10 years, the 60W bulb was not broken, because we did not use this light much. The video shows one reason why. It is in the same room with 45W inverter fluorescent lights. Maybe now with 1/10 the prior power it will see more use. The light quality is surprisingly good, similar brightness and no noticeable flicker.
A prior bigger LED bulb I bought flickered so bad, I gave it away to a laboratory, and it turned out the worst flicker among seven light bulbs, including an incandescent, and a CFL. Sorry, that report is proprietary. You can easily check for flicker if you have a digital camera with you. Aim at the lamp of interest and see if there are dark and bright stripes on your live display. I saw some, but they did not show up on my shopping photos.
[UPDATE 2011-10-23: captured the flicker on this new larger LED bulb, Sharp DL18AN]
The Money
Is it worth investing almost 5000 yen for a single bulb of this new technology, compared to some 250 yen for a mini-krypton bulb of the Edison type? What is the payback time? Let us calculate.
Electricity price 27 yen per kWh (daytime tariff, between 23:00 and 07:00 down to 9 yen)
Electricity savings 60 W - 6 W = 54 W (0.054 kWh in 1 hour)
Hours of use to recover 5000 yen: 5000 / (27 x 0.054) = 2500 h
That is 635 days, about 2 years, for a light used about 4 hours every evening, not counting the price and time wasted for replacing 2-3 incandescent light bulbs. It justifies the high price for a technology that is new but not that difficult to manufacture. Expect prices for LED lamps to fall further as mass adoption takes place.
Changing from lightbulbs to CFL, the breakeven appears similar. CommonCraft explains (video 03:11).
Rather quick - 2 years for a break-even, considering it takes 7 years for changing to an inverter refrigerator and 13 years for a photovoltaic solar system to pay back the initial investment. Higher electricity prices will shorten the payback time, lower prices lengthen it.
No, changing from fluorescents to LED is hardly worth it. If the power consumption were half, it would take 10 years or more to break even
Is it Green Yet?
The manufacturer does not publish the energy it takes to make the LED bulb and ship it here (made in Indonesia). However, we can safely estimate the cost of embedded energy would not surpass the factory price, otherwise the maker had certainly no profits.
Making a worst-case assumption here, factory price at 50% retail (~2500 yen), how much would this be in energy?
2500 yen / 27 yen/kWh = 93 kWh
Time to recover this assumed embedded energy from the savings of 54 W equals 0.054 kWh/hour
93 / 0.054 = 1722 h, 431 days, some 14 months.
Conclusion: the solution is green, it recovers its embedded energy, even if the device does not reach its projected lifetime at 40,000 hours
Too simple without a Life Cycle Analysis? Show me where it would change the outcome.
Prohibit Incandescent Light Bulbs?
These new light bulbs do help turn ligthing green as can be, yet, as an electrical engineer I am not convinced they are a viable solution for every household application.
Here is why:
In every home there are places with light bulbs that never seem to break. Toilet, staircase, storage chambers, for example. These lamps are on for so little time that putting in a CFL or a LED is a complete waste of money and embedded energy unless we recover the lamps before the building is torn down and keep using them in the new place.
The EU ban on incandescents reeks of a different agenda. It is not that I am against regulation. In the construction sector, the only way to reduce wasting energy from insuficient heat insulation is to require minimum efficiency by building codes. It is necessary because the builder/owner pays the price for energy efficiency while in most cases the benefits accrue to the tenant. Different pockets, no incentive. Hence, the law is needed. But for light bulbs, that anyway account for only 10-20% of home energy consumption?
Complaints, comments, congratulations?
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