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3.1 Light bulbs3.1 Light bulbs

As an illustration, let’s have a closer look at light bulbs.

The following video will illustrate to you all the LCA steps detailed until now, and will stop each time you will have a question to answer.

To ensure a service of 6000 hours at 600 lumen, what do you need to buy? (your reference flows)

One economic light bulb or 6 incandescent bulbs and:

6 * 60W * 1000h = 360kWh for incandescent bulbs

11W * 6000h = 66kWh for low energy bulb

Video start...06:55 to 12:43 people to consult;13:48 to 14:40 what is the system function?

STOP14:40 to 14:52 answer14:52 to 14:57 what is the secondary function?

STOP14:57 to 17:34 answers17:34 to 18:42 what is the functional unit of the system?

STOP18:42 to 20:31 answer20:31 to 20:35

STOP

20:35 to 27:46 answer with description of low energy bulbs

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3.2 Light bulbs3.2 Light bulbsenvironmental key parametersenvironmental key parameters

– the number of lumen per watt (performance of the bulb),

– the life time.

The former has to be maximized for the use phase. The latter directly influences the environmental load for the raw material extraction and the manufacturing stage.

Further analysis is however required to assess the relative importance of these different development stages.

27:46 to 27:57 what are the key parameters?STOP

27:57 to 32:08 answers

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3.3 Light efficiency for different sorts of 3.3 Light efficiency for different sorts of bulbsbulbs

Beware comparing an emerging technology which has not yet been optimized with a well established one which has been improved over years.

On the second graph, you can see that efficiency of light bulbs has improved of a factor 1000 over 100 years. Turning a new technology into an efficient one requires time.

32:08 to 34:41 properties of bulbs through time

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3.4 Light bulbs3.4 Light bulbseconomical considerationseconomical considerations

But the purchasing cost is not the only one that has to be considered. The whole economic costs can easily be calculated and compared on the basis of the same FU, applying a life cycle costing approach:

– an incandescent bulb is about 1$,

– low energy fluorescent bulbs cost 10$ each,

– electricity is about 0.1$/kWh (use phase).

Please feel free to calculate the corresponding investment costs…

Price is often raised as a main objection, since the low energy bulbs are more expensive.

34:41 to 36:46 problems with those bulbs

36:46 to 37:10 what is the price?STOP

37:10 to 46:16 answer and remarks