Who said anything about APM only being used by laptops? [LWN.net]

Who said anything about APM only being used by laptops?

Posted Apr 3, 2011 20:23 UTC (Sun) by Trelane (subscriber, #56877)
In reply to: Who said anything about APM only being used by laptops? by giraffedata
Parent article: Powering down APM

> (time to recover the cost) is not the proper measurement here. The proper measurement is the present value of all the electricity savings for all time minus the cost of the new hardware.

I'm just a physicist; could you please reformat this as an equation? With the variables and constants clearly explained.

> showed that the electricity for the remaining life of the CRTs

What does this mean, precisely?

> cheaper than the price of the LCDs

These aren't the same units. Electricity is in energy and price of LCDs is in some currency. Presumably you're converting units someplace; where is that taking place?

> to buy the LCDs, the company would have to reduce its investment in its core business

I don't understand why you had to reduce investment in core business.

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Who said anything about APM only being used by laptops?

Posted Apr 3, 2011 20:34 UTC (Sun) by dark (subscriber, #8483) [Link]

I'm not a physicist, but maybe I can act as a bridge here.

giraffedata was comparing two possible scenarios:

1. Continue to use the CRTs until they were due for replacement anyway (let's call that time T1), then replace them with LCDs.

2. Discard the CRTs now (let's call that T0) and replace them with LCDs

In scenario 2 you use less electricity in the timespan from T0 to T1, which saves money, but you also move the expense of buying the LCDs from T1 to T0, which means you lose the profit you could have made from investments of that money between T0 and T1.

For a profitable business, the most natural investment is in its own operations, which is why giraffedata was talking about income from the core business.