The Glossary defines and explains terms used in the evaluation, measurement, verification (EMV), and market research of electric and gas energy efficiency, conservation, load management, demand response, and other demand reduction activities that regulators, policymakers, and other non-technical readers will encounter as they pursue their work. Included are terms commonly used in the processes of EMV; terms associated with the energy efficiency measures being installed and the equipment or facilities within which they are installed; terms associated with program strategies that might be included in E, M & V studies; and other terms often found in evaluation reports. Version 1 of the Glossary was completed in 2009. Version 2.1, which adds about 65 terms that were not included in the first version of the Glossary, including environmental terms, was completed in 2011.