What Is Daylight-Saving Time? | Wired Science | Wired.com: Now let me assume an average price for energy at $0.1 per kilowatt*hour. Of course, this price varies with location. This would put the cost savings per day at $10 million dollars. If DLS is 200 days (I think it is actually 238), this would put a total yearly savings of $2 billion. That is compared to a gross domestic product of 14 trillion dollars for the USA.