To move the United States toward greater energy independence and security, the U.S. Department of Defense (DoD) seeks ways to reduce energy use intensity, electricity demand, and energy costs in its building portfolio, as required by legislation. One approach toward meeting this mandate is enhancing building controls to (1) minimize energy usage in response to occupancy schedules, (2) utilize weather forecasts to shift loads in advance of heat and cold waves, and (3) decrease expenses and increase revenue stream from the utility’s demand response (DR) programs. While building automation system (BAS) operators can readily achieve energy and cost savings for a few buildings through changes to the building controls, the task becomes more difficult to implement across a campus of buildings. Campus-wide savings are particularly complicated because even state-of-the-art BAS are incapable of coordinating electricity demand among buildings.
The objective of this project was to demonstrate the ability of a Collaborative Building Energy Management and Control (cBEMC) system to empower deep occupant-engagement that can achieve ongoing building energy savings and, on command, to obtain a targeted fast load-shedding relative to baseline building total load. Specifically, the team sought 30% HVAC energy savings and 20% of electric load reduction through the cBEMC deployment. Also tested were greenhouse gas emissions reduction, greater occupant control and engagement, and increased occupant comfort and satisfaction.
cBEMC is a vendor-independent software platform that enhances the capabilities of an existing BAS by actively engaging occupants in energy management and comfort control for their environment. These capabilities are designed to improve building energy efficiency and the ability to rapidly respond to fluctuations in the grid. In particular, the following innovations were introduced by cBEMC:
- “cBEMC Controller” - a runtime software component that is integrated with BAS network and communicates with BAS server via Building Automation and Control Network Communication Protocol (BACnet protocol). It is also connected to a virtual private network exposing parts of its controlling functions to building occupants and facility management via Web Human-Machine Interface (HMI). cBEMC controller provides real-time methods for occupancy-based energy management, and comfort-based building environmental control to optimize building energy efficiency and to manage DR events.
- Social network-type participation of building occupants in energy efficiency and DR events.
- HMI for social interaction among building occupants.
- Visualization of energy centric results to promote healthy competition among building occupants for energy reduction.
- Dynamic DR capability to achieve rapid target load shedding capacity in response to grid or microgrid needs.
The project team deployed and demonstrated cBEMC at Building 300 of the 171st Air Refueling Wing of the Pennsylvania Air National Guard located at the Pittsburgh International Airport in Coraopolis, Pennsylvania. A series of system tests were conducted to measure the performance of cBEMC with reference to a baseline conditions. The tests were grouped into two test scenarios – energy efficiency (EE) scenario and DR scenario. Two weeks of real data coupled with one year of Transient System Simulation platform (TRNSYS) simulation were used for the performance analysis. The table below provides the summary of the overall achievements for each performance objective.
Quantitative Performance Objectives
PO 1: Building Energy Use Reduction
30% annual reduction in HVAC energy usage and 10% annual reduction for overall building energy consumption.
Average reduction achieved was 14% and the best case scenario of 22% HVAC reduction.
Corresponding overall energy reduction (including electricity) were 10.4% and 15.8%, respectively.
PO 2: Facility Electric Load Shedding
Load shedding by 20% within 15 minutes lasting for 60 minutes
Over three DR test average kW/kWh reduction achieved was 28%
PO 3: Scope 2 GHG Emissions
Target was achieved.
Reduction achieved was 20%
PO 4: System Economics
Simple payback in 5 years
Qualitative Performance Objectives
PO 5: Occupant Control and DSM
softThermostat used weekly by occupants; and real time use for setback and DR
PO 6: Occupant Comfort and Satisfaction
Improvements in occupant satisfaction; IEQ measurement meets ASHRAE standards
PO 7: FM / Operator Feedback
Averaged rating greater than 5 (out of 7); and desire of FM to continue using the system
ASHRAE = American Society for Heating, Refrigerating and Air Conditioning Engineers DSM = demand side management FM = facility manager GHG = greenhouse gas HVAC = heating, ventilation, and air conditioning IEQ = indoor environmental quality
This project demonstrated the feasibility of a secure integration of individual building controls to a central campus energy management center in a secure network environment. As is common when designing and implementing control technologies that have a wide range of capabilities, field conditions are not always optimal to fully “test drive” a technology’s controls and algorithms. The team was not able to achieve some of the objectives due to several onsite constraints; whereas, some objectives were only partially achieved. In spite of the constraints, cBEMC performed as expected most of the time and the system increased energy awareness among building occupants.