How do we know if our work done implementing changes for better energy performance was successful? To measure the impact of the change on performance, we need to measure energy performance before and after the change, and compare them. However, adjustments must be made to account for other changes that took place that impacted energy usage, but that had nothing to do with the energy improvement project that was implemented. For example, building occupancy may have changed over the course of an improvement project, or perhaps there was a change in the hours that the building was open for occupants. Measurement and Verification is the process of determining energy savings before and after the implementation of a project or program and making appropriate adjustments based on changes in conditions.