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In this project, Siemens Corporate Technology (SCT), in collaboration with the Boeing Company, DNV KEMA, and the University of California at Berkeley (UCB), deployed and demonstrated an integrated building control system called the Intelligent Building Energy Management System (iBEMS) in four buildings at the United States Air Force Academy (USAFA). The team’s objective was to achieve energy savings using iBEMS to implement advanced, integrated control for building cooling/heating, lighting, ventilation, and plug-load management, while still providing a healthy, productive, and comfortable environment for the building occupants. An additional goal was to demonstrate a dynamic DR approach to shave or shift aggregated building peak load in response to a request from the grid, microgrid, or BAS operator, through iBEMS. Finally, the project team demonstrated the feasibility of a secure integration of individual building controls to a central campus energy management center in a secure network environment.
iBEMS is a vendor independent energy management platform that extends BAS capabilities by means of integration with advanced optimization, control, and visualization technologies. The core component is the Siemens smart energy box (SEB), which resides at both campus (microgrid) and building level to oversee a building cluster and subsystems within the buildings, including heating, ventilation, and air conditioning (HVAC) control, lighting control, and local controllers for the on-site energy resources and distributed loads. SEB is a runtime system with several basic function components developed through earlier effort in order to perform HVAC and plug loads demand response control, including a BACnet adaptor, an OpenADR client, a weather service adaptor, an Energy Plus simulation engine and an agent framework for plug load control. This project extended SEB’s capabilities with a rule-based energy efficiency implementation, a collaborative and adaptive building cluster demand management, and advanced microgrid energy management human machine interfaces.
A series of system tests were conducted in four buildings at USAFA to measure the performance of iBEMS with reference to baseline conditions. The tests were grouped into two test scenarios—an energy efficiency (EE) scenario and demand management scenario—and conducted from the perspective of the iBEMS system user who may be the facility manager, a building operator, an energy manager, or a base commander. The table below provides a summary of the overall achievements for each performance objective (PO). The results for POs 3 and 4 reflect the scaled results for a campus of 14 buildings that were selected from within the USAFA site.
Demonstration Results Summary
Performance Objective (PO) | Success Criteria | Performance Assessment |
|---|---|---|
Quantitative Performance Objectives | ||
PO 1: EE Optimization | 20-40% annual reduction in energy usage in Arnold Hall | 32% reduction with results scaled using EnergyPlus simulation |
PO 2: Demand Reduction | 15-30% demand reduction for a cluster of three buildings | 11.4% reduction of total building load; 28% reduction of actual controllable loads |
PO 3: Greenhouse Gas (GHG) Emissions | 20% reduction | 15% reduction |
PO 4: System Economics | 15% direct cost saving; simple payback in 5 years | 19.2% direct cost saving; simple payback of 3 years for campus wide iBEMS implementation |
PO 5: Security/Reliability | Secure communication; no significant effect of latency | Achieved |
Qualitative Performance Objectives | ||
PO 6: Occupant Comfort | Plug-load reduction with up to 50% participation; no substantial complaints by occupants | Site-specific constraints disallowed plug-load controls for EE and DR events; very few complaints |
PO 7: System Integration | Ease of use; flexible interface; better load control for DR | Achieved |
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. For site-specific reasons, building lighting and plug-loads, which are a major portion of electrical consumption at USAFA, were not allowed to be controlled for any EE or DR events. Only HVAC loads were allowed to be part of the EE and DR events; even so, among HVAC loads only a subset of air handling units in each building were allowed for participation in EE and DR events. Given these constraints, it can be safely stated that iBEMS performed as expected and was able to achieve most of its performance objectives.
For the Life Cycle Cost Analysis (LCCA), in the case of single building installation, without security costs, net present value of the iBEMS system over a 15 year period is $149,999, representing a 3.38 savings-to-investment ratio (SIR) and a 4 year simple payback. For campus wide installation, the net present value of the iBEMS system over a 15 year period is $4,550,053, representing a 5.76 SIR and a 3 year simple payback.
The commissioning and demonstration of the iBEMS system at USAFA helped the development team to understand the advantages and constraints of the current iBEMS implementation in the areas of equipment, integration, and communication as well as user experience of the system. Refer to the Cost and Performance Report for specifics.