You know how much they spent, and they also, say, because they had to contract with the local government to get the power provided, you might know what they made a deal to buy, so you know how much power it takes.
Sappiamo quanto spende, e avendo negoziato con il governo locale, per la fornitura di energia, possiamo sapere  cosa hanno concordato di acquistare, quindi sappiamo quanta energia ci vuole.