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Comment by blutfink | Hacker News Reader

Headline is wrong. 68GJ per month, not GW, which is roughly 26kW.

And this is why it's always good to do a quick order of magnitude "does this make sense?" check on computations. Off-hand, the total electricity generating capacity in the US is about 1,000 GW, so it'd be quite obvious that making one webpage less resource-intensive wouldn't result in a reduction of 6% of that total.

When converting 68GJ to another unit of energy, it would be 18,888KWh or ~18GWh (note that h!).

EDIT: But of course, 18GWh/68GJ "per month" also gives us an average continuous power consumption of 26KW, as you have said.

No, he just dropped the per month part. 68 GJ / month, is 68 * 1 billion watts / 30 * 24 * 60 * 60 seconds, is 26 kw

EDIT: Doh! It appears I missed what blutfink was trying to say and that their changing of quantities from energy to power was intentional. Sorry for the confusion.

Whenever you have an energy use figure over a specific period, it is perfectly legitimate to calculate the average power, just as if it took you 30 min to reach your grandmother's house, which is 60 miles away, then you averaged 120 mph. In this case, an average power is an appropriate measure, as we do not know how long this page will be in service.

Yes. I was not sure how familiar people are with joules, so as I said in the post:

> (In the headline I used GW because people are more familiar with that, and it's kind of the same.)

Saying "kind of the same" won't please engineers who know what they're talking about and are used to correct units, but for the general public who won't read beyond the headline and (if I'm lucky) the conclusion, I think it's close enough. I am just hoping to get people's attention to the fact that an inefficiently coded redesign of the 6th largest website on the planet has impact.

Rather than just being flat out wrong, why not use gigawatt-hours which is a well known unit.

Because I find Wh (or kWh or MWh or...) a very weird unit. The Watt is already a "per second" unit, and the appended hour makes it have a double time component in the definition. While a Wh has a simple joule value (3600 if I'm not mistaken) and so it's directly convertible, I still find it more difficult to wrap my mind around. Joules seem like a better unit, but they're not known to people... but maybe you're right and I should have picked that.

All over the world, the watt-hour is the unit of electrical power consumption among the general public.

I suppose you're right at that: by trying to dig deeper to understand it, I confused myself and stopped using what is the generally accepted standard... I guess I should indeed have used kWh.

Hey I don’t mean to pile on you. This is cool work that you did that highlights an important issue.

"Adding the hour" doesn't make it have "two time components" -- it makes it have no time component.

The joule is a unit of ENERGY.

The watt is a unit of {WORK,POWER}. Confusingly, the germanic languages use "Work" for the concept ("Arbeit" in DE or "Arbeid" in NL), but in English it is "Power". Power means transfer of ENERGY over TIME. Specifically, the Watt it is defined as one Joule per second.

So Watts are a unit of POWER. And POWER=ENERGY/TIME. Note that this is a divison, not a multiplication!

So what do you get by multiplying a Watt by a unit of time (in this case hours)?

  > We're multiplying: WORK * TIME  [Watt * Hour]
  > Which is: (ENERGY/TIME) * TIME  [(Joule/Second) * Hour]
  > And the result is.....: just ENERGY

As you can see, the Watt-Hour is a unit of energy, just like the Joule. There is nothing weird about it.

Hope that could clear things up -- best greetings from the Netherlands!

https://www.google.com/search?q=68GJ+in+kwh

It's not that hard to specify kW.h, which is what people are used to paying for in their utility bills.

18888.9 kW.h are worth about 3k USD, depending on your local rates.

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