About STAC

Project Information Center

Hydrogen Education

Previous Solicitations

News

Presentations

Contact

Home

STAC

Project Information Center

STATEMENT OF WORK

Project Title:

Real Time Predictive Optimal Control of Active and Passive Building Thermal Storage Systems

Contractor:

University of Colorado-Boulder
CEAE Department, CB 428
Boulder, CO 80309
(303) 492-3389

Program Area:

Buildings

Partners:

University of Nebraska-Lincoln
Johnson Controls

Project Description:

Develop, test, and implement a robust real-time optimal controller for commercial buildings that simultaneously utilizes both the capacity of building thermal mass and thermal energy storage systems to optimize cooling and ventilation equipment operation under dynamic electricity rates. For regulated and deregulated utility environments, this load management and optimization technology will be integrated with the building automation system to minimize energy consumption and electrical demand as well as operating cost while ensuring human comfort.

Management Plan (Approach):

The unique nature of STAC requires that projects be supported by multiple State entities, and to the extent necessary any other entity. As indicated in the STAC Agreement, it is the Contractor’s responsibility to coordinate the execution of work under the Contract, incorporated by reference hereto. Contractor, in conjunction with the other State entities, and to the extent necessary any other entity, shall conduct the project in accordance with the Management Plan (approach) described below.

The management of the research project will be carried out by the University of Colorado-Boulder who will handle all contracting and subcontracting issues. The University of Nebraska will be a subcontractor throughout the duration of the project. Dr. Moncef Krarti, will be the program manager for this contract. The project is undertaken as a joint effort between two state-chartered institutions (University of Colorado and University of Nebraska) and Johnson Controls, Inc. as the industrial partner. The University of Colorado will be the principal contractor and will carry out testing of the optimal controller in its state-of-the-art HVAC lab facility. Johnson Controls is an industry leader in innovative building control systems and building services. Corporate research activities by Johnson Controls Inc. focus on the advanced development of next-generation control applications and equipment that yield improved occupant comfort, reduced natural resource consumption, and cost-effective building operation. The University of Nebraska will carry out field implementation and testing of a prototype for the optimal controller.

The research plan for the proposed project is divided into two consecutive phases: Phase I includes the design and laboratory testing of the real-time optimal controller while Phase II involves field testing of prototypes of the proposed controller in two commercial buildings: one in Colorado and the other in Nebraska. Each phase covers a 12-month period and includes several tasks as described in the following sections.

Phase I: Laboratory Testing

In Phase I, a prototype real-time optimal controller for active and passive thermal storage inventory will be developed and tested in the full-size HVAC Laboratory of the University of Colorado at Boulder.

Task 1: Design a Prototype Controller

Key system design features for the optimal controller have already been defined in a previous study by the PI and Co-PIs including: engineering-based model for the building energy systems (using EnergyPlus) with a proven real-time system identification method to adequately mirror the actual building dynamic response. The calibration of the building model can be properly performed with very little measured data. The proposed model (i.e., engineering-based) provides better accuracy and flexibility compared to commonly used simple models (i.e., regression-based).

Task 2: Prepare HVAC Laboratory for Controller Evaluation

The purpose of this task is to set-up the HVAC laboratory including the existing ice storage system with the necessary level of instrumentation as well as thermal mass to allow for meaningful experiments to be conducted. The outcome of Task 1 will determine how the controller will be integrated in the laboratory BMS as well as the required data points to be monitored and control parameters to be adjusted during the experiments. The HVAC lab setup and the specification of the building management system will be carried with help from Johnson Controls, Inc.

Task 3: Design Lab Experiments

During this task, a suitable series of lab experiments will be designed to deliver the experimental data necessary to evaluate the performance of the real-time optimal controller and to refine any controller design and/or functional features. Conventional control strategies will have to be incorporated in the experiments so that the performance of the proposed optimal controller is compared to existing technology. It is expected that at least 50 different tests will be performed in the laboratory.

Task 4: Conduct Lab Experiments

The purpose of this task is to conduct the lab experiments determined in Task 3. It is anticipated that the experiments will be carried out during the first year of the project with each test requiring a 48-hour period (to account for the preparation time as well as the period for the actual test performance). Because the HVAC lab can provide air at any desired temperature and humidity profiles with the help of an outdoor conditioning system, the lab tests are independent of the seasons and can be conducted throughout the year.

Task 5: Analyze and Interpret Lab Experiments

In this task, data post-processing (i.e. consistency checks, removal of outliers, correction for climate conditions), analysis and evaluation of the collected data (from task 4) will be carried out. In particular, cost savings performance, energy consumption, active TES and passive building mass storage utilization, and equipment cycling will be among the most important results to be analyzed. In addition, the experiments can reveal the accuracy and the robustness of the building dynamics model, the TES and equipment models as well as the performance of the system identification approach that adjusts the model parameters to mirror the behavior of the actual building and plant.

Task 6: Phase I Documentation

After completion of Tasks 1 through 5, a final report for Phase I will be prepared. The findings and documentation identified in individual tasks will be integrated into a single document that summarizes the work product and deliverables.

Phase II: Implementation in Field Setting

The main objective of Phase II is to test the performance of the real-time controller in actual buildings under real weather and operating conditions using two selected field sites (one in Colorado and the other in Nebraska).

Task 7: Identify Potential Field Test Sites

Suitable field test sites will be identified for a realistic evaluation of the proposed technology's performance benefits. In reference to the endorsement shown in Appendix B, Johnson Controls, Inc. will aid in finding suitable test sites in both Colorado and Nebraska. A database of large commercial buildings with thermal energy storage systems, their geographic locations, weight of construction (and thereby thermal capacitance) and technical specifications will be set up. A set of typical applications will be defined using feedback of TES experts and the database of available site candidates for each state. A short-list of candidates will be defined, and each candidate will be asked to participate. Once potential candidates have been identified, the effort of instrumentation and integration into the existing building management system will be assessed and the most suitable candidates selected.

Task 8: Prepare Field Site for Controller Evaluation

The selected field site with will be equipped with the instrumentation necessary for meaningful field experiments. Based on the controller design (see Task 1) and the available BMS in the selected buildings, the required data points to be monitored and the control parameters to be adjusted will be identified. A fail-safe configuration will be developed to bypass the experimental controller in case of hazards and failures.

Task 9: Design Field Tests

Suitable field experiments will be designed that deliver the experimental data necessary to evaluate the performance of the predictive optimal controller under real-world conditions. At least one conventional control strategy will be incorporated so that the predictive optimal controller is compared to existing technology. Most likely, this conventional control strategy will be the one executed by the controller already in place. Using the fail-safe configuration, the building energy systems will alternately be governed by the predictive optimal controller and the existing conventional controller. Proper accounting will be taken of beginning and ending storage inventory to avoid misinterpretation of the results.

Task 10: Conduct Field Tests

The field tests developed in Task 9 will be carried out for approximately six months with emphasis on the peak summer cooling period during year 2 of the project.

Task 11: Analyze and Interpret Field Tests

Collected data will be post-processed (i.e., consistency checks, removal of outliers, correction for climate conditions), analyzed and evaluated. Cost savings performance, energy consumption, human comfort, storage utilization, and equipment cycling will be among the most significant results. The field tests will help quantify the relationship between building and equipment model accuracy with controller performance and the adequacy of the system identification that adjusts the model parameters to mirror the behavior of the building and cooling plant equipment.

Task 12: Phase II and Final Documentation

After completion of Tasks 7 through 11, a final report for Phase II and the entire project will be prepared. The findings and documentation identified in individual tasks will be integrated into a single document that summarizes the work product and deliverables. The final report will be composed of the individual documentation of Phases I and II.

Dissemination Plan

University of Colorado and University of Nebraska plans to actively disseminate the findings of research to enhance scientific and technical understanding, through master’s and doctoral research work, through technical manuscripts in refereed journals (International Journal of HVAC&R Research, ASHRAE Transactions, Building and Environment Journal, and ASME Transactions) and through presentations of the project results in national and international conferences (IEEE, ASHRAE, ASME, and ASCE). Therefore, research efforts will be thoroughly evaluated by the research community through the peer-review process.

A written synopsis about the project will be written for an audience with a broad technical background. In particular, the synopsis will summarize the main findings of the project and the significance as well as the benefits of the findings to building designers, operators, and managers. The synopsis will be submitted to widely received professional publications such as the ASHRAE Insights.

It expected that at least two technical papers to be prepared shortly after the completion of the project.

Project Tasks, Status, and Deliverables

Last Updated: 10/24/06