Lock Up Load Curtailment
The county pursued traditional energy retrofits at the Santa Rita Jail, the county's largest energy user and, in the spring of 2002, completed the fourth largest solar electric system in the world on the roof of the jail. While these energy savings initiatives were significant, the county leadership looked for additional technologies to increase the energy savings and reduce their dependence on volatile grid power.
With the installation of Viron Energy Services UtilityVisionSM, a Web-based integrated metering and control technology, county personnel can now incrementally power down the chillers in the courthouse as well as four other county buildings, through any computer with an Internet connection and standard Web browser. This allows the county to efficiently manage energy use while maintaining occupant comfort all with the click of a mouse.
The MotiveAs the summer of 2001 approached, the county of Alameda was concerned about the volatility of energy prices, anticipated energy shortages, and the threat of blackouts. Between the fiscal years of 2000 and 2001, the county's overall annual energy costs increased approximately 25%. Also, over 50 of the county's facilities were hit with rolling blackouts during January and March of 2001.
Because the county had already initiated a lighting retrofit project to improve efficiency, the hvac system was targeted - specifically, the two Trane 400-ton centrifugal chillers in the county's main courthouse. Prior to the installation of UtilityVision, the county's existing bas provided the building operator little flexibility in controlling these large loads. This not only made it difficult for the county to curtail energy use, but also to maintain occupant comfort within the buildings.
The five largest energy-using buildings in the county's system were the Santa Rita Jail, main county courthouse, Fremont Hall of Justice, Hayward Hall of Justice, and the Wiley Manuel County Courthouse. Most of the buildings were built between the early 70s and late 80s.
The Alameda County Courthouse was constructed in the 1920s. These five county buildings comprise approximately 2 million sq ft and contain 10,100 occupants. The primary uses of the buildings are court proceedings, criminal detention, and administration. If the county could somehow curb electric demand in these buildings, significant savings could be captured.
Viron was already working with the county at the Santa Rita Jail in Dublin, CA. Viron and PowerLight Corporation, a Berkeley, CA firm, were in the process of installing traditional energy-saving equipment, such as high-efficiency motors, vsd's, a chiller replacement, and a bas upgrade as well as expanding the current rooftop solar array. PowerLight's technology was selected because it not only provided energy savings from solar electric generation, but offered additional benefits of hvac savings through thermal building insulation and extended roof life.
As this project progressed, Viron's Bill Kelly was searching for funding sources for the project and subsequent energy-saving projects when he came upon the AB 970 grant program of the California Energy Commission (CEC). The program is designed to provide large energy users with grant monies to install "enhanced automation" technologies. The ultimate goal of AB 970 is to enable large energy users to curtail load during high or peak demand emergencies and to provide tools for the eventuality of real-time pricing. The availability of this grant money opened the door for the leaders in Alameda County to look at energy information systems as another means to save energy.
Opportunity And WeaponViron's proposal to the county included energy calculations detailing the potential load reduction at several county facilities as well as a successful application for a CEC grant in the amount of $260,000. Matt Muniz and his team worked with Viron to complete the CEC grant application.
With financing in place, the county proceeded to have Viron install UtilityVision and activate the curtailment module. The curtailment module is a Web-based load curtailment program that would make the county's bas more flexible in the face of energy price fluctuations, energy shortages, and blackouts.
The curtailment program would allow the county to set controls to incrementally power down its chillers and connect the affected facilities' utility meters to the Internet so that the effect of the chiller load reductions on facility-wide loads could be verified in near real time from any computer with an Internet connection and standard Web browser.
The curtailment plan for each facility is to reduce the central cooling plant demand in two steps. Step one would reduce the output capacity of the chiller plant by implementing a chilled water temperature reset strategy or limiting the current draw of the chiller. Step two would completely lock out all central plant equipment for a period not to exceed two hours.
Viron decided to implement step one using the current limiting strategy. The chilled water reset strategy would be more effective at reducing demand during partial-load conditions because it would trim the chiller output regardless of actual load conditions. The current limiting strategy would be more effective at peak conditions because it prevents the chiller from ramping up to match the extreme load conditions, which is when the rolling blackouts occur anyway. Once the curtailment strategy was determined, the question of how best to implement it had to be answered.
One of the goals of the project was to enable the curtailment signals from the Internet using UtilityVision, and use the existing energy management system to perform the actual curtailment control.
At the four courthouses, this meant expanding the existing CSI (TAC Americas) bas and integrating it into UtilityVision. The existing CSI system was expanded to provide current limiting control to the chillers, not just supervisory scheduling control. For the Santa Rita Jail, this meant expanding and integrating with the Honeywell bas, which was being installed as a separate project.
To enable this control, Trane added a Summit chiller control panel at Wiley Manuel Courthouse to interface with the existing chiller control panel and reprogrammed an existing Summit panel at the main county courthouse. The Summit controller interface allowed the CSI system to send each chiller a current limiting signal. At the Fremont Hall of Justice and the Hayward Hall of Justice, the CSI system was expanded to the chillers so that a current limiting signal would be sent directly to each chiller.
Viron worked with TAC Americas and with Trane in each of these cases to expand the bas' to provide the necessary chiller controls. In addition, Viron installed a UtilityVision panel in each facility, which would send a contact closure signal (one for each curtailment step) to the EMS' at each of the facilities. Upon receiving the curtailment signal from UtilityVision, the EMS would then limit the chiller to 50% capacity under step 1, or turn the chiller and its peripheral equipment off under step 2.
The entire installation took less than four months and LaCombe indicated that Pacific Coast Trane went above and beyond the call of duty to integrate the controls into the chillers and provided Viron and the county with exceptional service.
Curtailing With SecurityThe major components that make up the UtilityVision panel were created by EnFlex Corp. (Prescott, AZ). EnFlex engineers and network designers have focused their expertise and resources since 1994 on creating an embedded, networked system that is capable of integrating any number of enterprise sites.
Viron installed an EnFlex MG-200 Internet gateway and an EnFlex IO-12 universal controller at each of the county's five facilities. The EnFlex gateway is a conduit between the Internet and the county's local area network (LAN) through which curtailment signals are received from the Web and metered data from the facility is transmitted. The EnFlex controller supplements the capabilities of the EnFlex gateway. When a curtailment signal is sent from the Web, it goes through the gateway to the controller, which in turn sends a contact closure signal to the EMS.
To curtail load, the county logs onto the UtilityVision website (www.utilityvision.com), which is hosted on a server at Viron headquarters in Kansas City. At the website, a user can, with the authorized passwords and a few clicks of a mouse, initiate curtailments at any or all of the five facilities, for any length of time. When the user confirms the curtailment, the File Transfer Protocol (FTP) over the Internet, through the county's firewall, to the targeted facilities. At a targeted facility, the commands are received by the EnFlex MG-200 and sent to the IO-12. This controller will then close either contact closure 1 or 2 depending on which curtailment was selected.
To verify the impact of the curtailment, Pacific Gas & Electric Company installed a pulse initiator on the primary electrical meter in the four courthouses. A primary electric meter had already been installed at Santa Rita Jail under a separate project. Each of these meters is connected to the EnFlex gateway, which records 15-min kW and kWh incremental data. The gateway then sends the data out over the Internet to a database located on the UtilityVision website. County personnel may access and view each facility's instantaneous demand as well as historical demand data.
As with any Web-based project, the information systems (IS) group within the county of Alameda played a significant role in this project. The biggest concern regarding connectivity was keeping the county's network security intact. The county IS group configured its firewall to restrict outside access to its wide area network, which serves the entire county. The firewall only allows inbound communications to the UtilityVision panels from one specific public IP address, and then only on selected firewall ports. By working with the IS group during the engineering stage of the project, the installation and commissioning project stages were successful.
Returning To The SceneThe county now has the ability, through a single website, to shed a total of about 1.248 MW of load within minutes in the event of an emergency. This ability not only helps bolster the reliability of the region's electrical system, but also makes the county eligible to receive state incentives for curtailing load when blackouts are imminent. More precise control over the chiller settings also allows the county to use less energy, while maintaining occupant comfort.
According to Muniz, "UtilityVision and our upgraded building automation system make us feel more prepared for whatever may come in terms of real-time pricing schemes."
Interestingly, the primary benefit that the county realized as a result of installing the new enhanced automation system was one that it had not anticipated. Through a password-protected website, the new system provides the county continual, remote access to 15-min energy use information for the facilities that received upgrades. According to Muniz, access to this data has been "tremendously useful" for verifying that actual building loads reflect intended use.
The county is also well positioned to take advantage of real-time pricing should it arrive. Many of the county facilities operate on a 9 am to 5 pm schedule, therefore, using energy during the daytime peak when it is most expensive. Their new control system allows the county to respond quickly and effectively to increases in the retail price of electricity.
This project not only generates community and regional goodwill, but it also elevates Alameda County's status as a progressive energy leader and a responsible environmental trustee. ES