How to find efficiencies
Efficiency is simply a measure of success–it tells you how much energy is squandered and how much ends up in the store that you designed the system for. Often, but not always, the squandered energy will be shifted to many stores–dissipation has occurred.
Calculate the percentage of the input energy ending up in the desired output and you have the efficiency: efficiency = energyoutenergyin × 100 %.
Here's a support sheet showing how to calculate efficiency: