Balancing Supply and Demand:
Part 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, for example on an extremely hot day? 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 that provide an incentive for building owners to decrease usage in response to a curtailment signal (see our column in Engineered Systems July 2008 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 or RTP. In many ways RTP works like demand response, allowing better balancing between supply and demand. The key difference is that RTP could potentially be deployed on a daily basis, while demand response 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 building automation system 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.
While 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 demand response strategies such as modifying space set-points 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 system 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.
Paul and Ira first worked together on a series of ASHRAE projects including the BACnet committee and Guideline 13 – Specifying DDC Controls. The formation of Building Intelligence Group provided them the ability to work together professionally providing assistance to owners with the planning, design and development of Intelligent Building Systems. Building Intelligence Group provides services for clients worldwide including leading Universities, Corporations, and Developers. More information can be found at www.buildingintelligencegroup.com