Demand response can be defined as “Changes in electric usage by end-use customers from their normal consumption patterns in response to changes in the price of electricity over time, or to incentive payments designed to induce lower electricity use at times of high wholesale market prices or when system reliability is jeopardized.”, “Demand Response entails customers changing their normal consumption patterns in response to changes in the price of energy over time or to incentive payments designed to induce lower electricity use when prices are high or system reliability is in jeopardy”

There are differences between energy efficiency and demand response. Energy efficiency keeps the same level of output, but less energy consumption; However, demand response encourages customers to reduce their usage at peak periods.

There several technologies used for demand response. These technologies are meant to monitor and dynamic control of electricity. Smart meters are one of these technologies.

There are two types of demand response.

1-Emergency demand response

In the case of extreme event, the demand will increase from consumers. If the demanded power was above the power generated, a call will be made to make a minimum usage from all consumers.

2-Econamic-demand response

This type is meant encourage consumers to get paid when they decrease their usage during peak hours.

http://en.wikipedia.org/wiki/Demand_response

http://www.drsgcoalition.org/resources/factsheets/Demand_Response_and_Energy_Efficiency.pdf

http://www.enernoc.com/our-resources/brochures-faq/faq-pjms-economic-demand-response-program