Energy Audit:

An energy audit is an inspection survey and an analysis of energy flows for energy conservation in a building. It may include a process or system to reduce the amount of energy input into the system without negatively affecting the output.

Energy audit types:

Preliminary audit:

• The preliminary audit (alternatively called a simple audit, screening audit, or walk-through audit) is the simplest and quickest type of audit.
• It involves minimal interviews with site-operating personnel, a brief review of facility utility bills and other operating data, and a walk-through of the facility to become familiar with the building operation and to identify any glaring areas of energy waste or inefficiency.

Investment Grade Audit(IGA):

• An investment-grade audit is the most detailed energy audit.
• It analyzes the financial aspects of energy savings and the return on investment from potential changes or upgrades.
• A building operator typically uses the investment-grade audit as a budgeting tool when planning facility upgrades.
• This audit finalizes the modeling performed during a general audit and combines the information gathered with monetary figures.
• Life-cycle cost analyses can determine the long-term cost savings associated with installing a new boiler, energy-saving windows, or fluorescent lighting.

Benchmarking:

• Benchmarking mainly consists in comparing the measured consumption with reference consumption of other similar buildings or generated by simulation tools to identify excessive or unacceptable running costs.
• As mentioned before, benchmarking is also necessary to identify buildings presenting interesting energy-saving potential. 

Detailed Energy Audit:

Detailed Energy Audit evaluates all systems and equipment which consume energy and the audit comprises a detailed study on energy savings and costs.