Renewable energy certificates (RECs or tradable certificates) are certificates that represent a specified amount of power generation from independent renewable energy power producers. Utilities can purchase RECs to help meet renewable portfolio standards (RPS) in lieu of developing their renewable capacity when it is either infeasible or undesirable. RECs help build the renewable production base even when geographic constraints are not amenable to a utility installing new renewable capacity in the RPS jurisdiction. Similar to RECs, white tags, or energy efficiency certificates (EEC), encourage and reward the efficient use of electricity. They trade very similarly to RECs but are defined through energy savings calculations and are earned through strategies such as installing an energy management system, installing energy-efficient chillers or lighting. Once created, the tags can be retained or sold in the mandated, voluntary or carbon markets in which buyers and sellers are brought together by Sterling Planet, which manages the entire white tags life cycle. See also utilities and energy efficiency.