Engineering360: "Turning off the lights can save lives"

Can anyone tell me what a 12% increase in (summertime) efficiency means?

I was always of the understanding that Efficiency = Energy Out / Energy In

If this is supposed to mean that the electrical energy consumption is reduced by 12%, that's a number I can understand.

Seems obviously intuitive. Less used, less generation, lower cost and less pollution. Why did it take a study to come to this obvious conclusion? How much difference is it making with LED lighting? How much difference are energy star appliances making? I use both but my electric bill doesn't seem to go down!

something doesn’t seem to fit - reducing use of lights will reduce my overall electricity cost by 5c/kwh?

my local cost is 10c/kwh.... so if i turn off some lights i’ll cut my bill in half? my house is almost exclusively LED lighting.

clearly this presumption is flawed; some info on the raw data and how this was determined would be helpful.

Not to be morbid, but how much more energy and emissions will result with 475 saved lives? Was this also considered in the analysis?