May 2017

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George HernandezEMAIL INTERVIEW George Hernandez and Ken Sinclair

George Hernandez, Principal Technical Advisor, Buildings to Grid Integration and Buildings Controls Research Program Manager, PNNL

George Hernandez received an M.S. degree in mechanical engineering from the University of California, Berkeley. He joined the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, in 2009 and worked in the Advanced Building Controls group. He is a staff scientist and senior demand-side management professional. He has coauthored the High-Performance RTU Challenge, the Buildings Performance Database, the Low-Cost Wireless Metering Challenge, Energy Information Handbook, the Portable Sensor Suitcase, Open Source Small Building Control System, and the Transactional Network project. Most recently, he has championed the development and market transfer of an open-source software platform called VOLTTRON, used to deploy transactional control strategies for buildings to grid integration. He has extensive knowledge, skills, and capabilities derived from a substantial career in demand side utility management across a wide variety of commercial and industrial sectors and utilities as both a corporate employee and an independent consultant. He is a licensed professional engineer by the state of California.


An agent based open-source distributed control and sensing platform for buildings, the power grid, and the integration of the two to support the deployment of energy efficiency and grid services to increase consumer benefits.

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SinclairSeveral years ago, you introduced our readers to VOLTTRON.  How is the effort going?
Hernandez:  Things have been going swimmingly well!  We have been very busy building out the VOLTTRON platform and supporting the implementing of several proofs of concept projects to validate various US Department of Energy driven control theories that allow buildings to be more tightly coupled to the grid.  Fundamentally, this has positioned VOLTTRON (which your readers can find at to be:

Sinclair:   That sounds great.  Can you describe some of these proofs of concept projects?
Hernandez:  Sure.  Fundamentally these new control theories need validation in real buildings using real energy:

If you are interested in learning more about these projects and others, you and your readers are invited to attend our fourth annual VOLTTRON Workshop, this year co-sponsored by PG&E at the Pacific Energy Center in San Francisco on May 16th and 17th.

Day 1 will focus on VOLTTRON hardware, applications, and solutions. You’ll learn about ongoing projects at the national labs and universities that leverage this open-source platform to seamlessly connect data and devices to make and act on decisions. We’ll also have speakers from the industry that will share their VOLTTRON solutions.
Day 2 focuses on the developer community. We’ll do an overview of the VOLTTRON platform, covering topics ranging from security to device configuration. The afternoon will be spent discussing various use cases and deployments of VOLTTRON. Finally, we’ll also do a live “Office Hours” that mimics the format of our bi-weekly university and industry call.
Register at

Sinclair:   Is there any opportunity for others to utilize this new work?
Hernandez:  Absolutely.  All of the work has been funded by the Department of Energy and is open source.  The code has been validated by PNNL to be ‘clean,’ following the cyber secure utility principles, and is properly coded and documented is available for download on GitHub

The base VOLTTRON software is readily available at GitHub (including the engine, drivers, historians, etc.) to enable a Python coder to install and implement the VOLTTRON system. The projects I described earlier are collections of V-Agents or VOLTTRON Apps operating in the VOLTTRON environment according to the professionals control implementation strategies -- that’s where the magic really occurs.  These Apps are innovative, powerful, and limitless.

For example, one of the VOLTTRON Apps -- Intelligent Load Control (ILC) -- is an algorithm that can actively manage loads while also considering (and valuing) constraints for those loads, like an occupant’s comfort, a manufacturer’s recommended runtime, occupancy load, etc. In this example, to manage to comfort constraints, the ILC algorithm can dynamically prioritize the available HVAC related loads for curtailment using both quantitative rules (e.g. deviation of zone conditions from set point) and qualitative rules (e.g. type of zone) in a building.

The applications for this type of V-Agent are very broad and can include most any type of device, either energy-consuming or energy-generating, for most any kind of load management requirement allowing the shape of the building load to be dynamically controlled, governed, or altered. These applications include Demand Response, Demand Limiting, Ancillary Services, and can include electricity ramping to match generation. VOLTTRON allows us to explore building utilization to the utilities beyond traditional demand response. For example, this ILC algorithm uses analytic hierarchy process (AHP) to prioritize loads for curtailment. 

VOLTTRON exposes controls and equipment in new ways. Another App -- On-Demand Defrost -- is a strategy for performing automatic as needed, on demand defrosting of refrigerated display cases and related equipment. This new defrosting control application uses temperature sensors that already exist within most commercially available refrigerated cases to infer the formation of ice and, hence, the need for defrosting. Because the V-Agent uses sensors that are already installed, the application of this new defrost technology requires only the utilization of the V-Agent code. This one App alone -- validated to save 75% of the energy required to defrost a refrigerated display case – illustrates how powerful these new control opportunities are to the consumer and how the research pioneers scientific discoveries!

[an error occurred while processing this directive]Sinclair:   It seems that VOLTTRON is no longer a laboratory experiment and is close to being ready for prime time.  What are your thoughts on VOLTTRON’s maturity?

Hernandez:  PNNL is continuing to develop the core VOLTTRON code to enhance features and maintains capabilities like cyber security, driver implementation, scalability, and API’s (including a base OpenADR agent).  PNNL is continuing to proof out new control theory concepts for DOE (like transactive control, transactive energy, grid integration) as that work is more fundamental technology research to prove feasibility and to develop the technology. But we have been working very hard, in parallel, to move VOLTTRON out of the national lab and into an open source software foundation and community.  This growing and firming up of the VOLTTRON community will provide a sustainable resource for commercial entities who want to develop specific solutions on an open source software platform.  It’s critically important to understand that PNNL will continue to provide that critical role I described earlier – leadership within the research community (within the profession and within academia) in developing control applications for the testing and validating of emerging control theories. 

I would love to tell you more about this initiative. However, the fourth annual VOLTTRON Workshop, this year co-sponsored by PG&E at the Pacific Energy Center in San Francisco is right around the corner -- on May 16th and 17th (register at, and I don’t want to steal anybody’s thunder…

Sinclair:  For further reading an interview with a VOLTTRON user.


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