The Role of HVAC in Smart Grid Solutions If we start to examine the drivers behind Grid Interactive Efficient Buildings, some key ideas start to appear.

Richard McElhinney Vice President of Technology at Conserve It https://www.conserveitiot.com/

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The idea of a "Smart Grid" has been written about and researched across all major developed markets, with many national governments providing regulatory frameworks that encourage the development of Smart Grid Technologies and Solutions.

When contemplating such technologies and solutions it is important to consider the drivers behind a Smart Grid, of which there are many, as well as understanding the concept of Grid Interactive Efficient Buildings, a term coined in multiple reports published by the US Department of Energy as recent as 2019. The idea that Efficient Buildings, or Smart Buildings in our current vernacular, should also be interacting with the infrastructure that provides the electricity for all the building systems found in a modern building, can still be a foreign concept to many who deliver automation and smart solutions into modern Efficient Buildings. This is despite years of research and discussions around Grid Interactivity and Smart Grids being conducted.

Characteristics of Grid Interactive Efficient Buildings

If we start to examine the drivers behind Grid Interactive Efficient Buildings, some key ideas start to appear. Demand Side Management is an umbrella term describing the different ways, methods, and measures that advanced controls and automation systems can deliver to manage the electrical demand that a building places on electrical grid. Other core ideas such as Demand Response, where a building responds to signals from the Smart Grid operator or electricity utility to reduce demand for the benefit of improved Grid stability, and Demand Charge Management, which refers to control strategies that continuously manage the electrical demand of a building to stay within pre-defined limits, work together to realise the idea of a Grid Interactive Efficient Building.

Within a Smart Building, many systems work together to provide efficiency whilst simultaneously meeting the demands of tenants, facility managers, and owners alike. However, as has been demonstrated in many studies, HVAC systems are the single largest consumer of energy in a building and, in commercial buildings, places the highest electrical demand on the Smart Grid. This characteristic alone makes HVAC systems within a building a prime candidate to deliver on Demand Side Management strategies mentioned earlier such as Demand Response and Demand Charge Management. There are however other characteristics of HVAC that make it more than suitable for delivering a Grid Interactive Efficient Building. HVAC systems lend themselves, through properties like thermal inertia within the building envelope, to be almost charged like a battery. By implementing strategies such as "pre-cooling" we can deliver a strategy known as Load-Shifting. In this case, a building is pre-conditioned when the Smart Grid determines that current demand on the grid is low. This establishes control of the heating or cooling load of a building early during a normal operating day and allows it to reduce the loads later in the day at peak demand.

Figure 1 Building Flexibility Load Curve - source: https://www1.eere.energy.gov/buildings/pdfs/75470.pdf

Similarly, for buildings or scenarios where Load-Shifting are not suitable, Load-Shedding is another option. Load-Shedding allows for HVAC systems to be "turned down" or even turned off for periods of time in response to signals from the Smart Grid. Stakeholders in a Smart Grid and Grid Interactive Efficient Building, such as tenants and Facility Managers, can agree on timeframes and space or zone temperatures that guide how a Load-Shedding will work. There are many ways Load-Shedding can be used to manage these parameters and it does get complicated in real world applications, nonetheless it is HVAC systems that can do this work. The third characteristic can be applied with both Load-Shifting and Load-Shedding, the characteristic of Modulation. HVAC systems, with the correct equipment such as the use of VFDs amongst other components, can be modulated to react in tune with their control variables. One of those control variables that is to be considered with respect to a Smart Grid is electrical demand.

The Times They Are A-Changin' (Bob Dylan)

All the concepts discussed would not be possible without advances in various aspects of technology. The latest Edge computing platforms provide significant control and optimisation capabilities that can be deployed within a building. By utilising new computing platforms, advanced Machine Learning can be implemented to create on-site Digital Twins of complicated equipment that has many variables to monitor and control across the whole building. Extending the use of Edge Computing platforms and embedded Machine Learning with Digital Twins allows the advancement of Model Predictive Control to assist in the delivery of Load-Shifting and Load-Shedding, two components that make up a strong Demand Response strategy. Model Predictive Control allows for Load-Shifting and Load-Shedding to be conducted accurately and to be extended with a view to maximising the financial benefits (where they apply in different markets) of Demand Response events. To realise the use of all of these technologies to form a complete solution, the latest in internet connectivity and telecommunications technologies need to be applied. These allows full and complete Grid Interaction to deliver a Grid Interactive Efficient Building.

Today's Smart Grid solutions are currently taking shape and early indications are that buildings will play a big role in the Smart Grid solutions of the future. Within each building lies the capability to affect how the building interacts with a Smart Grid and what a building can do to deliver Grid stability and reductions in electrical demand that are vitally important as new and varied energy sources are brought online. As discussed, HVAC systems combined with Building Automation can provide a strong platform for delivering results. Other components are needed to deliver a dynamic environment for managing and controlling the Smart Grid of today and the future.

Richard McElhinney Bio

Richard McElhinney is the Vice President of Technology at Conserve It, developers of PlantPRO™, a central plant control and optimisation platform, and international product developers and distributors for IoT, Building Automation, Smart Services and Big Data Analytics.  Richard has over 25 years experience in product and solution development having worked globally with leading companies in the Smart Building Services space.  Previously the Chief Software Architect at Conserve It and the Software Development Manager for Airmaster Australia, Richard has held numerous roles where he has delivered new and innovative solutions to the market.  As a member of the open source Project Haystack community since its inception and subsequently as a Director of Project-Haystack.org, an open source, 501C trade association focusing on the standardisation and technology around semantic modelling and making equipment and devices self describing, Richard has contributed to numerous aspects of the development of Project Haystack.  Richard continues to lead Conserve It to be at the forefront of central plant optimisation using Machine Learning and advanced mathematical modelling as well as furthering the goals and technology of Project Haystack to enable building owners and Facility Managers to unlock the value of data.