Typical LED lighting is approximately free, or close enough to zero that calculating a percentage change in cost isn't especially, ah, enlightening. The goal of

Typical LED lighting is approximately free, or close enough to zero that calculating a percentage change in cost isn't especially, ah, enlightening. The goal of the comparison is to attempt to contextualize the absolute rather than relative cost, relying on the monthly cost of air conditioning (approximately "a lot", or at least noticeable) being a more familiar value than the monthly cost of 100 light bulbs (which are individually so cheap as to vanish into noise).