[Beowulf] Re: "hobbyists"

Kilian CAVALOTTI kilian at stanford.edu
Wed Jun 25 10:57:59 PDT 2008

On Wednesday 25 June 2008 10:09:28 am Robert G. Brown wrote:
> (lower power means lower SOMETHING -- less agitation, less heating of
> the water, smaller capacity so you have to run more loads) 

Or just better energy conversion, less energy wasted in a transformer, 
use of higher-grade components (hence the higher price tag)... This 
kind of thing can also explain the differences.

> And it is equally easy to produce an "energy saving" product that
> saves energy by not working as well, or at all.  I'm not really
> arguing, by the way -- only pointing out that you should look beyond
> JUST the energy RATE of draw and make sure that the product will
> actually perform just as well 

Can you actually "try" washing machines in a store? :)

> and still save total energy and do what 
> you need it to do.  It isn't always easy to do that, and it goes
> beyond just looking at the power consumption rate.  Lower power could
> translate into "wearing slightly dirty clothes all the time" or it
> could translate into "getting a load that is just as large of just as
> many clothes just as clean -- but saving 2.5 KW every hour you use
> it."

That's precisely what Energy Labels are for:
For washing machines the energy efficiency scale is calculated using a 
cotton cycle at 60°C (140°F) with a maximum declared load. This load is 
typically 6 kg. The energy efficiency index is in kW·h per kilogramme 
of washing.

> If it IS heating water, then you need to be very careful.  It takes a
> certain number of joules to heat water, period.  

Yes, but again, to produce that certain amount of heat, it may require 
more or less electric energy depending on the efficiency of the  
conversion. Although I assume most components probably do about the 
same, ball park. I would think efficiency is more a determinant factor 
in motors, for instance.


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