A commercial building energy audit is a study of your building's energy using equipment. Building energy audits often also look at water consumption (even though that is not technically considered energy). An energy auditor comes out to your building and interviews facility managers, inspects lighting, air conditioning, heating and ventilation equipment, controls, air compressors, water consuming equipment, and anything else that is using energy. The auditor will develop a list of energy conservation measures (ECMs) that could reduce energy usage and costs in your building. Depending upon the level of building energy audit, the auditor will then quantify how much savings potential there is for each of these measures, and the costs associated with implementing them. Some measures will take decades to pay for themselves, while others will start paying for themselves within months.