Energy Efficiency & Conservation Certificates
This represent 1 megawatt hour of power conserved or load reduced. These are some times called EE certificates, EE credits, or White TagsTM. 
In 2007, IBM today announced the industry's first corporate-led initiative to enable clients to earn energy efficiency certificates for reducing the energy needed to run their data centers. The certificates earned -- based on energy use reduction verified by a third-party registry -- for the first time provide a way for businesses to attain a certified measurement of their energy use reduction, a key, emerging business metric.
The certificates can be traded for cash on the growing energy efficiency certificate market or otherwise retained to demonstrate reductions in energy use and associated CO2 emissions.