Building Automation: Smart Buildings Meet The Smart Grid
November 1, 2009
What devices could be shut off for the right price?Recently, there has been a lot of attention on a concept called the Smart Grid, with articles in major magazines and newspapers. The excitement is fueled by almost $4 billion in funding for Smart Grid demonstration and deployment as part of the American Reinvestment and Recovery Act. The Smart Grid concept is to develop a more intelligent and integrated electrical transmission infrastructure including use of smart two-way meters, connections of regional grids, and new grid management tools. Some even compare the Smart Grid concept to the internet, as being a decentralized model for delivery of power and services allowing for deployment of renewable power and electric vehicles.
We should expect that Smart Grid implementations may provide more reliable power, but what impact, if any, does this have on BAS? The answer is that it may have a major impact.
Balancing Supply and DemandPart of the concept of Smart Grid is to be able to better manage and control loads on the electrical grid. Traditionally, utilities did this by anticipating the loads and deploying a series of power plants for base loading (typically large coal and nuclear plants) and peak loading (usually smaller gas turbine plants). Utilities and regional grid operators are able to balance loading, providing a reliable supply of power on the grid.
But what happens when all of the generating capacity is deployed on an extremely hot day, for example? The result is typically a brownout or blackout where portions of the grid don’t get the necessary power. To prevent this, utilities have deployed programs called demand response (DR) that provide an incentive for building owners to decrease usage in response to a curtailment signal (see our column in the July 2008 issue of Engineered Systems for more details). While all of this works well today, the introduction of new and less reliable generating sources such as wind and solar, and the desire to make the entire process more efficient, is leading to new concepts that will be deployed as part of the Smart Grid.
For buildings, the most important is a concept called real-time pricing (RTP). In many ways RTP works like DR, allowing better balancing between supply and demand. The key difference is that RTP could potentially be deployed on a daily basis, while DR is only used for a few hours a year. It is anticipated that RTP will provide a price signal either through the internet or through a smart power meter. This price signal will show the current or anticipated price for power. The BAS will need to receive this data and then determine what actions need to be taken. While RTP is not yet in broad deployment, many BAS systems already have the capability to receive these signals.
Smart BuildingsWhile there are many challenges with deploying the Smart Grid and in connecting smart buildings, the biggest challenge may be deciding what loads within a commercial building can be shut off or shifted in response to an RTP signal. Using typical DR strategies such as modifying space setpoints or reducing light levels is one concept; however, these may adversely impact the occupants. While they may be acceptable for use a few hours a year, such strategies may not work on a more regular basis.
Other concepts require looking for loads that can be shut off with little, if any, impact on occupants or process. Examples of this may include the use of thermal storage, pre-cooling, and load shifting which includes turning off or cycling loads such as restroom water heaters, electric water coolers, signs, banks of elevators, fountains, and office machines. Development and deployment of these strategies will require connection to systems which are often not part of a BAS today, and to do this, owners will need a good financial model to justify this investment. Keep the Smart Grid in mind as you start to work on your next project, and think about how you can make the building a smart part of the Smart Grid. ES