Energy Audit - From US Dept of Energy:
Home Energy Assessment or Home Energy Audit
The first step to assess how much energy your home consumes and to evaluate what measures you can take to make your home more energy efficient. An assessment will show you problems that may, when corrected, save you significant amounts of money over time.
During the assessment, you can pinpoint where your house is losing energy. Energy assessments also determine the efficiency of your home's heating and cooling systems.
An assessment may also show you ways to conserve hot water and electricity. You can perform a simple energy assessment yourself, or have a professional energy auditor carry out a more thorough assessment.
A professional auditor uses a variety of techniques and equipment to determine the energy efficiency of a structure. Thorough assessments often use equipment such as blower doors, which measure the extent of leaks in the building envelope, and infrared cameras, which reveal hard-to-detect areas of air infiltration and missing insulation.