[Greenbuilding] energy and power terms

[David Bergman]

Completely agree. It's also why the term kilowatt-hours is so 
confusing to most folks (many of who think it is kilowatt per hour).

David

At 10:04 AM 11/21/2011, Alan Abrams wrote:
>methinks that what is problematical is semantical.  if it is gallons 
>of milk that are important to a mother, and gallons of milk per hour 
>that are important to a milkmaid, and if these terms are logical and 
>intuitive--then watts should logically be the term for the volume of 
>electricity consumed, and watts per hours should be the term for the rate.
>
>but it's not.  hence the confusion.
>
>On Mon, Nov 21, 2011 at 7:06 AM, nick pine 
><<mailto:nick at early.com>nick at early.com> wrote:
>David Bergman writes:
>
>The article also says, btw, that watts are comparable to horsepower. 
>But I do find their explanation before that rather confusing: "A 
>laborer working through the day will put out 75 watts of power. A 
>medium-sized car might consume 100,000 watts." Those sound like 
>energy totals, not flows.,
>
>
>Perhaps the intent was to say that the laborer can generate 75 watts 
>for a long time, vs 300 watts for a shorter time. And accelerating a 
>4000 pound car from 0 to 60 mph takes about 1/2mV^2 = 
>1/2x4000x0.454lb/kg(60x0.447)^2 = 653K joules. If that happens in 6 
>seconds, it might require a constant 653K/6 = 109K joules per 
>second, ie 109 kW for 6 seconds, or perhaps more power and smoke at 
>the beginning and less at the end, at a non-constant rate.
>
>Nick Pyner wrote:
>
>... If you must use automotive terms, I submit it might be better to 
>use the fuel gauge than the speedo.
>
>
>The rate of change of the fuel gauge is closer to power than the speedo.
>
>
>Or how about the engine? A watt is exactly like a horsepower, just 
>3/4 the size, and most of the world uses just that.
>
>
>One horsepower is about 3/4 of a kilowatt, like 10 75-watt people.
>
>Nick
>
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David Bergman  RA   LEED AP
DAVID BERGMAN ARCHITECT / FIRE & WATER LIGHTING + FURNITURE
architecture . interiors . ecodesign . lighting . furniture
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