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What is Automated Demand Response?

Solar, wind and other forms of Variable Renewable Energy (VRE) are beginning to change how we operate the grid.  While traditional forms of thermal generation, like coal, are dispatchable (called upon when needed), they are not flexible. My previous post discusses the market conditions that explain why integrating EE with DR is an attractive proposition for utilities who are experiencing disruptions from Distributed Energy Resources (DER) and Variable Renewable Energy (VER). Demand Response is one tool that gives system operators the dexterity they need to integrate more VRE into our power grids.  Today’s post will focus on how integrated EE/DR technology can autonomously shed load at the bequest of the utility.  We will overview how the Open ADR protocol works, the advantages that standardized DR protocol creates and discuss the role of the Open ADR alliance.

What is Demand Response (DR)?

Demand Response is a way for end-use electric customers to reduce kW demand during periods of higher power prices (peak periods).  Energy Events are called by service curtailment providers, such as RTO/ISOs to ensure additional capacity is available to the market as required.  Demand Response allows an electric customer to manage energy use in response to wholesale market conditions.  Customer participation is usually voluntary, and customers are commonly compensated for curtailing loads.  DR has traditionally focused on the largest commercial and industrial (C&I) customers – however this approach is maturating.  Integrating DR into energy efficient products is a new path to reach new customers.

What is Open Automated Demand Response (OpenADR)?

OpenADR is a method for a dispatcher to continuously broadcast a DR signal to a customer.  This gives the customer constant visibility to wholesale prices and better helps balance supply with demand.  The OpenADR Alliance describes the advantage of this approach as: “facilitating a timely and predictable response for the system operator, while allowing choices by the end customer[1]”.  OpenADR developed out of the California Energy Crisis of 2002.  OpenADR creates a common language, the ADR 2.0 protocol, for communicating a DR event over an IP based network, like the internet.  Numerous vendors now support this protocol which ensures operability when a system operator calls an event.

How does OpenADR work? – VTNs, VENs and DRAS’

OpenADR works by having end-use building systems that are pre-programmed to take an action based on receiving a signal.  Systems operators initiate a DR event through a Demand Response Automation Server (DRAS).  The DRAS is responsible for communicating specific details about the event, such as its duration, start time, and price signals to the end-use devices.  The below image from the OpenADR Alliance shows how third-parties and systems operators interface with the DRAS to automate functions like dynamic pricing.


In communicating the DR signal there are always two actors, the VTN (Virtual Top Node) and the VEN (Virtual End Node).  The VTN to VEN is always a“1 to many” relationship, meaning that a singular top node is controlling many end nodes.  VTNs are usually a utility or an ISO.  The VTN is responsible for broadcasting the specifics of the event, like the price, and schedule signals.  Demand Response Aggregators, or those who enroll end-use customers and sell their curtailed loads on the wholesale market, can be either the top node or an end node, based on who is calling the event.  Utility customers are the VENs that supply the curtailment to the demand aggregators.  VENs are the logical interface from which the load shedding occurs.


Why should we automate DR?

Automation helps simplify communication during the event, which leads to faster reaction times and more energy savings.  This rapid reaction helps limits distortions between the wholesale and retail markets, and helps keeps prices lower for everyone!

What do you think? Please like, share and comment over your network. While I enjoy sharing my opinion, my favorite part about blogging is hearing from all of you.

For more information on integrated EE/DR please visit our Knowledge Hub.  For specific information about our Smart Lighting Solutions program, please visit our  Knowledge Hub.

[1] https://www.openadr.org/assets/docs/openadr_primer.pdf

[2] ‘’

[3] https://www.gridwiseac.org/pdfs/forum_papers12/zuber_pres_gi12.pdf

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