What is an energy audit? How do you conduct an energy audit?

An evaluation of energy consumption, as in a home or business, to determine ways in which energy can be conserved.

Have your local utility company come in and they perform these typically for free. Ascertain where and how you can save energy and thus save money. Often rebates are given when you update a water heater, an air conditioner, a refrigerator, or put in new insulation.

Since it takes specific training, I doubt that a complete answer can be given here, it's a little like "how do you fly an airplane?" If you are looking for an energy audit for your restaurant, I'd encourage you to just call your utility company, and they will probably do one for you professionally, for free or low cost.