Making The Case For Energy Efficient Code

The current state of measuring the environmental impact of our IT infrastructure is missing a big piece of the puzzle. One of the metrics we use, power usage effectiveness (PUE), only looks at how much power entering a data center is being consumed by the computer hardware in relation to the total amount of energy the facility uses.
But what about the millions of lines of code running on that hardware? How can we know if that’s energy efficient code?