CBEI research has demonstrated through simulation that, for selected building types over a range of climate zones, HVAC package solutions exist that have the potential to provide at least 50% HVAC energy savings with a simple payback of 4 years or less.
This report is the pdf version of the CBEI Final report and results.
CBEI conducted research to develop and demonstrate a library of diagnostics decision support tools that can enable cost effective diagnostics solutions for existing buildings. This report describes early results in successfully developing and demonstrating the effectiveness of diagnostics and decision support tools for subsystem diagnostics (RTU, DX, AHU-VAV and building envelope subsystems) and fault prioritization.
A novel algorithm was tested against a large and diversified dataset comprising points from five buildings, two vendors, three distributors and more than 20K points. Overall the algorithm identifies about 90% of VAVs and 80% of AHUs and reaches an accuracy of about 90% in detecting the points required by a test application. The algorithm was incorporated into a VOLTTRON ready utility.
A fault detection and diagnostics system for rooftop air conditioners was developed using low-cost electronics. The system was designed to be compatible with the VOLTTRONTM platform. The underlying fault detection and diagnostics methodology utilizes virtual sensors to measure parts of the equipment operation that are sensitive to common faults. Using virtual sensors reduces costs while also providing accurate and reliable diagnostics.
This project implemented, validated and documented an automated system for training virtual refrigerant charge sensors for rooftop unit ACs. The system automatically tunes empirical parameters of a virtual sensor for estimating the amount of refrigerant in a system. The engineering time and costs associated with calibrating a virtual sensor are reduced because of the automated testing in an open laboratory and the reduced number of tests.
CBEI facilitated integrated visioning, expert workshops and design charrettes for Building 661, which contributed to the development of a report on enclosure technologies with an emphasis on engaging the building systems and systems integration critical to high performance retrofits. The report is focused on typical (older) small commercial buildings.
This paper presents Model Predictive Control (MPC) and Fault Detection and Diagnostics (FDD) technologies, their on-line implementation, and results from several demonstrations conducted for a large-size HVAC system. The two technologies are executed at the supervisory level in a hierarchical control architecture as extensions of a baseline Building Management System (BMS). The MPC algorithm generates optimal set points for the HVAC actuator loops which minimize energy consumption while meeting equipment operational constraints and occupant comfort constraints.
A practical control algorithm for coordinating bot AC and refrigeration equipment was developed and evaluated using an energy simulation testbed for a convenience store. It was validated using actual convenience store data. The simulations allowed evaluations of savings for the unit coordinator compared to conventional control over a cooling season. The controller was designed to minimize implementation costs in that it does not require additional sensors and is self-learning.
Field demonstrations provided test and evaluation data for virtual sensor based AFDD concepts and provided a laboratory demonstration on the VOLTTRON platform.
HVAC package solutions were identified that met the stated objectives, based on 6 building types (quick service restaurant, full service restaurant, small hotel. large hotel, supermarket, and convenience store) in 6 region/climate zone combinations.
This report presents an overview of the development of the Energy Audit Tool along with case study results from the analysis of 40 buildings, and nine audited buildings at the Philadelphia Navy Yard.
CBEI conducted modeling and demonstrations to evaluate multiple technologies, including air movement strategies, ultraviolet germicidal irradiation, hybrid ventilation and under floor air distribution, ventilation and shading systems, impact of roof color and roof insulation, lighting and shading controls and devices, high performance glazing, roof retrofit technologies, photosensor controlled electric lighting, and swirl diffusers.
A scalable low-cost optimal chiller plant control algorithm was developed and effectively demonstrated with 128 case studies covering a variety of chiller plant load variations with each case being a weekly simulation of whole-building dynamic HVAC system models with closed loop local controls and supervisory chiller plant controls. Model-in-the-loop (MiL) analysis suggests a promising average energy saving of ~15% for medium office buildings and an average energy saving of ~10% for large hotel buildings.
This project developed and demonstrated novel techniques for cost-effective AFDD for Air Handling Units for small/medium commercial buildings. The diagnostic accuracy is over 95% and the payback period is less than two years.