December 2009

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How Buildings Will Communicate With The Smart Grid: The Applications and Protocols

The Applications and Protocols

  Jim Sinopoli PE, RCDD, LEED AP
Managing Principal,
Smart Buildings LLC

Contributing Editor

The electrical utility grid that Thomas Edison initiated over 100 years ago is long overdue for an overhaul. It will be a 180 degree change in the utility business model, going from selling more and more energy to consumers to putting everyone on a healthy energy “diet”. The entire concept of the utility grid, buildings, vehicles, energy sources and energy storage all communicating with one another to enable the efficient use of energy is ambitious and breathtaking. It will be the details of implementation that will determine its success.

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Smart buildings, smart grid

Much of the Smart Grid is obviously focused on utility grids not necessarily buildings. However, some of the characteristics of the Smart Grid effort addresses the integration of distributed energy resources, demand response, demand-side resources, ‘‘smart’’ appliances and consumer devices, plug-in electric and hybrid electric vehicles, thermal-storage air conditioning, and timely information and control options for consumers. Intuitively we know that a smart grid without smart buildings would be a greatly diminished deployment and a very expensive lost opportunity.

The larger question is what are the attributes and characteristics of the connection between smart buildings and the smart grid? What are the applications? What is the communications interface? How will it be addressed technically? What could or will it mean for building owners and facility management? Buildings are being designed and upgraded to be energy efficient but that effort often is disconnected from the Smart Grid initiative- how do we get the two in sync? Let’s start with the possibilities of applications and then review the possible communications protocols.

Demand Response
One of the top priorities of the Smart Grid is demand response, an economic mechanism to have customers reduce or increase demand. When used to reduce demand, utilities reduce their peak demand and the additional need for plant and the related capital costs. Using demand response for increasing demand is intriguing. During periods of low demand and high production a utility may want to increase demand to users that can store the energy and make use of the energy later (much like charging a big battery at the customer’s site).

The communications between the grid and a building can be two-way with the grid initiating communications to the building and the building acknowledging the signal and letting the utility know of their capability to respond. The building owner’s response to a demand response notification can be manual or automated. Manual response means people go around and shut lights off or turn thermostats down, obviously an inefficient and somewhat ineffective action to a signal from a technology-laden utility grid.

Automated means the grid signals the building and the building systems automatically respond by turning off lights and equipment, adjusting set points, etc. How this communications between the grid and the building systems takes place is still being worked out. If the demand response is “anticipated” it is possible that typical building systems in non-residential buildings may be able to be scheduled to react. If it’s dynamic however, as utility rates are projected to be, the grid must communicate real time with the building systems. The basis of that communication appears to be open standards‐based technology such as XML, SOAP and Web services, as indicated in version one of an Open Automated Demand Response communications specification. The communications standards for pricing formats and time-of-day schedules need to be established. While that framework looks solid it would take some advanced or enhanced building management systems to accommodate that communication and in turn adjust the energy-related building systems. The number of existing buildings that are currently capable of doing so is very small.

Distributed Generation (DG)
As more alternative on-site energy sources (solar, wind, co-gen) are used, buildings will be seen as both energy consumer and potential energy provider. As an energy provider the building or campus could supply energy back to the grid. That integration of on-site energy generation into the grid will require much more than communication. It also needs to address the verifying of the quality of the energy provided, security and safety. The movement of energy back and forth from the grid is another important area where standards will need to be developed.

Energy Information to Consumers
Energy Information to Consumers
Consumers will need information which can assist them in energy management. Some of the information and data may come from the grid and some may come from the building systems. For residential applications this data and information could include:

• Energy use – real-time and historic data on the amount used (KWH) , the cost, the rate schedule or purchasing terms for energy, the trends and the projected forecast of usage and costs
• Power sources - the amount and cost of renewable energy sources that are used, the carbon content of the energy used, and the distance from energy source
• Weather forecasts
• The quality and reliability of the power

For larger commercial customers this information will need to be more granular, more technical and in line with the reporting requirements for cap-and-trade, LEED, Energy Star or government requirements. Any information from the grid will need to be supplemented with information from the building systems.

Plug-In Hybrid Electric Vehicles (PHEV)
Plug-In Hybrid Electric Vehicles (PHEV)
Associated with buildings are the cars that are driven to and from the building, usually resulting in a significant portion of surface use or facilities for parking cars. Add to that the gradual penetration of hybrid and electric cars that need to be connected to the grid to be recharged that are also capable of storing electric power and providing it back to the grid. This is somewhat futuristic given the currently small number of PHEVs and the lack of advanced batteries but the potential over the next decade is huge. The general idea is that PHEVs could be recharged at off peak hours (middle of the night) and store energy that could be transferred to the grid during peak load times. It may not be as easy as it sounds. When the PHEV gets recharged will depend on when the driver wants to use the car, how much the batteries are discharged and what the time-of-day energy rate is. This area is much like distributed generation where the standards for bi-directional flows of energy and two-way communication and control capabilities are lacking.

Building Control Systems and Devices
A smart grid that simply provides energy information to home owners and building owners, and presumes that they will manually turn off lights and equipment and reset thermostats will flounder. To a large extent, the success of the smart grid will depend on the control systems within the buildings and the seamless and automated interaction between the building and the grid. Most buildings will need to integrate their control sub-systems, provide more sensors for the sub-systems and larger buildings will need to provide sub-metering. Proprietary building control systems will be unable to communicate and interact with the grid without some gateway or middleware. BACnet is identified in the first draft of operational standards as the preferred facility communication protocol for the meter interface. Here are some examples of how this may play out for residential, commercial and institutional buildings.

Control Solutions, Inc For residential the typical setup for a demand response program will be smart thermostats, control switches on the air conditioning and water heater and a display for providing energy information. Smart thermostats will allow a homeowner to set the temperature but outside of a certain range around the set point, the utility grid would control temperature. The same is true for switches on air conditioning and major equipment.

Larger commercial and institutional buildings will probably need to upgrade and integrate their building control systems, install metering systems with sufficient granularity, and potentially address the connection of wind, thermal and solar energy sources into the grid. Interestingly, one of the recent Smart Grid Investment Grants from the US government went to Honeywell ($11.4 million). They will provide automated peak pricing response for about 700 customers. Honeywell is planning a two step approach: first work with customers to develop a schedule of which equipment, banks of lights and power loads can be reduced during peak pricing and for how long; the second step utilizing their Tridium platform with the Open ADR standard to communicate with the grid and in turn control the building systems.

Standards and Protocols
The National Institute of Science and Technology (NIST) is responsible for coordinating the identification and development of the protocols and standards to achieve interoperability of Smart Grid devices and systems. After several iterations and public hearings for comment they released a draft report in September. NIST has identified applicable existing standards and also gaps where standards will need to be developed. The priority areas include: demand response, consumer energy efficiency, wide area situational awareness, electric storage, electric transportation, advanced metering infrastructure, distribution grid management, cyber security and network communications. They have identified 77 standards or specifications that can be used in the Smart Grid. Sixteen standards were initially identified as having strong consensus; that was expanded to 31 after public comment. An additional 46 standards were identified as potentially applicable. For those areas where gaps were identified, such as demand response, end-user energy information, time synchronization and so forth, draft standards are expected to be released in 2010.

What are the standards that have been identified that are most important for buildings? Out of the 77 here’s a list of the standards that could impact a building’s interaction with the Smart Grid:


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