Paraphrasing, "The great thing about the US Government is it's so big, if the optimal solution would save 30%, but you find a suboptimal solution that only saves 29%, nobody will notice because you're still saving tens or hundreds of millions of dollars of savings."
One of his big projects was on energy efficiently in remote military camps. The cost of fuel per gallon was around $100 delivered to parts of Afghanistan. They had tons of portable generators running at ~20-40% of capacity. If memory serves, ~70% is most efficient. By some combination of building a small or connecting a few tents to a single generator, they were able to very significantly reduce the fuel required and improve the quality of service.