# Talk:Energy efficiency

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## Lack of Citations

Difficult to use any of this data in a research paper since obviously Wikipedia is not a citable source. An entire section of the artile does not referece to any source material. 165.95.24.46 (talk) 20:01, 7 April 2008 (UTC)

## The Definition given here is to narrow, and that is misleading

It is often mistakenly thought that "efficiency" is the synonomous with the efficiency factor. That is only true, if both quantities on the right hand side of the definition

efficiency = benefit / effort (that is the general definition)

have the dimension of "energy" or "power". But very often the benefit has nothing to do with energy. For example, the benefit can be a mileage (unit "miles"). The effort e.g. is the fuel needed (unit "gallons") and the efficiency of this service will be given by

mileage / (fuel consumption)

with the unit "miles/gallon". In Europe the inverse value

effort coefficient = 1/efficiency

is established: the specific fuel requirement in (liter fuel)/(100 km). Such values characterising the efficiency are not "efficiency factors" - they are values with a dimension. It is not possible to introduce an efficiency factor instead of these quantities. Looking at most services produced by the use of energy you will find, that they do not have the dimension of energy.

That sound like an academic question? No, not at all. This is a key insight.

Let us look at an example: The efficiency factors of heating boilers can not be increased to more than 100% (law of energy conservation) and contemporary values already are in the range of 90%. But: the efficiency of the total service "heating" (to be measured by the area heated with a given amount of fuel) can be increased almost without any limit - by better insulation and heat recovery. If you only look at the efficiency factor, there will not be a noteworthy potential for energy saving for heating. But if we have a broader look at the service and realise, that the so called "heating demand" can be reduced to values near to zero (by insulation and heat recovery), we will understand that there is a huge potential for better efficiency. This has been demonstrated by the multitude of Passive Houses which have already been built and are occupied.

But it is not only true for heating, it is quite similar with many other applications of energy: At the end of the supply chain, the final use is made out of the energy supplied. At this end there are the major potentials for an increased efficiency: And it is not a few percents which can be saved; it is the major part - in most cases.

WF 2006-11-08 Reference: Dr. Wolfgang Feist, Source: http://www.passivhaustagung.de/Passive_House_E/efficiency_factor.html

## Clean-up Redirect

I agree that the content is too narrow. The article Energy conversion efficiency is more complete, and refers readers to the more specific terms and equations (e.g., Thermal efficiency). As such, I will 'boldly' redirect to it. 129.237.114.171 19:28, 21 November 2006 (UTC)

If the goal is to broaden the content of this article, then I would argue against redirecting it to energy conversion efficiency. Although the energy conversion efficiency article is indeed a more information-packed article than this one, its intended focus is limited to the efficiency of energy conversion machines whereas this article has a broader focus intended to cover the efficiency of all sorts of processes, not just those whose end purpose is to convert energy from one form to another. (As an example, consider the efficiency of a resistor; a resistor does not fall under the category of an energy conversion device, yet it is still appropriate to calculate its efficiency through use of the Work / energy formula.) I have removed the redirect for this reason, but I will watch for further discussion on this issue. Riick 03:51, 27 February 2007 (UTC)

## Work != Energy

I'm making the appropriate changes since work is in units of watts, not joules -- Autumninjersey 16:34, 12 June 2007 (UTC)

Work is measured in joules, power is measured in watts. Richard001 (talk) 01:14, 20 April 2008 (UTC)

"output is the amount of useful work (in watts)"...

• a) what is "useful work"? as compared to simply "work"? What does the addition of the word "useful" mean?
• b) If work is measured in Watts, is useful work also measured in Watts? (see a).) Sholto Maud 06:26, 14 June 2007 (UTC)

Useful work is the work you want it to do. For example, in a car, turning the wheels and powering the radio is useful, whereas losing heat into the air and creating loud noises isn't (unless you want the loud noises and heat) Strdst grl (talk) 15:26, 23 February 2008 (UTC)

## Energy Efficiency and Global Warming

I propose that we move this section to Efficient energy use. Sholto Maud 00:14, 14 July 2007 (UTC)

I concur. Cxw 19:37, 15 October 2007 (UTC)

## Renewable energy

"California implemented ... renewable electricity supplies" What sorts of renewable energy? I've heard tales of biofuel usage, like corn, not being as carbon neutral as one might think. Diversely wild areas supposedly take up more carbon than biofuel is supposed to save. —Preceding unsigned comment added by 24.1.229.114 (talk) 09:56, 15 March 2008 (UTC)

## How is Efficient energy use different than Energy conservation ?

Article should clarify - eg. Is one technical (about improving device efficiencies, house design ...) and the other about changing human behaviour (drive/consume/use less) ? - Rod57 (talk) 21:16, 8 December 2015 (UTC)

This is already clarified in the lead of the 'conservation' article with "Energy conservation differs from efficient energy use, which refers to using less energy for a constant service." That these are different does mean that this page seems to be appropriate for disambiguation as opposed to a broad concept article. Klbrain (talk) 16:22, 28 December 2015 (UTC)

## Move discussion in progress

There is a move discussion in progress on Talk:Efficient energy use which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 12:00, 25 June 2016 (UTC)