Reducing building energy use through the implementation of energy efficiency projects is a proven strategy. However, claims of energy efficiency savings must be supported by measurement. Clients, investors, program administrators, and other stakeholders now require quantifiable evidence that the contract or programmatic goals have been met. For every project—whether lighting retrofits or HVAC optimization—providing evidence of energy savings is a critical element to ensure limited dollars are spent in the most cost-effective manner. M&V is the process of quantifying savings delivered from an energy conservation measure. An important element of verification process is that it isolates the energy savings delivered by the project from other factors affecting energy consumption, such as weather or building occupancy.