What is Automated Fault Detection and Diagnostic (AFFD) and How to Apply at Your Facilities

Otto Van Geet, NREL
Celeste Cizik, Group14 Engineering, Inc.

As large commercial buildings strive for ever increasing levels of energy efficiency and operational performance, design engineers are specifying increasingly complex and sophisticated HVAC and building automation systems. Over time, this increased complexity often broadens the gap between design intent and the in-situ performance of commercial buildings: equipment degrades, controls change, and facilities operation staff may be unable to keep up with maintenance requirements. As a facility's operational performance declines over time, energy use goes up and interior thermal comfort may degrade.

The primary goals of a commissioning effort are to ensure that the building systems operate as originally designed, provide a safe and healthy facility, improve energy performance and minimize energy consumption, reduce operating costs, and ensure adequate O&M staff orientation and training.

Retro-commissioning (RCx) is a commissioning process undertaken to resolve operational problems, improve comfort, and optimize energy use for the current use of the building. Typical RCx efforts evaluate the operational performance of a building at a fixed instant in time, repair HVAC components that aren't working correctly, and modify control sequences and schedules as needed. Once the RCx effort concludes, the building performance slowly starts to degrade as equipment malfunctions, occupant needs change, and changes are made to the control system.

An Ongoing Commissioning (CCx) solution looks to maintain the savings achieved by the RCx and obviate the need for periodic RCx events. In an attempt to ensure that building performance doesn't start to degrade at the end of an RCx effort, a number of vendors have started offering automated fault detection and diagnostic (AFFD) tools that aggregate data from all of the available data sources within a building and perform real time diagnostics to identify suboptimal performance. Advances in BACnet communication protocols, onsite data storage capabilities, and electrical submeters have enabled the automated collection and aggregation of large quantities of real-time building performance data for these AFDD software tools.

This presentation will cover AFDD software tools and how they can be applied to lab buildings. The NREL S&TF is a seven year old, LEED-Platinum high performance laboratory building that was in need of retro-commissioning and was chosen as the pilot site for AFDD using SkySpark on the NREL campus in FY 2014. The project resulted in a 7% whole building savings for low / no cost ECMs with a payback period of under 2 years. The presentation will provide details of how retro-commissioning using AFDD was applied to the NREL S&TF and results.

Learning Objectives

  • Participants will gain an understanding of what AFDD is.
  • Participants will understand the benefits of using AFDD as part of retro-commissioning
  • Participants will understand the results NREL obtained at the S&TF by hiring Group14, a retro-commissioning expert utilizing AFDD.
  • Participants will gain an understanding of how to evaluate their own facilities for the potential use of AFDD.


Otto Van Geet is a Principal Engineer at the National Renewable Energy Laboratory (NREL). Mr. Van Geet has been involved in the design, construction, and operation of energy efficient research facilities such as labs and data centers, office and general use facilities, and low energy use campus and community design. Mr. Van Geet was one of the founding members of the Labs21 program and provides technical guidance for the program. Mr. Van Geet is a PE, a CEM and a LEED AP

Celeste Cizik, PE, CEM, LEED-AP, PMP leads the Existing Buildings team at Group14 Engineering. She has over twelve years of experience in building energy engineering including retro-commissioning, energy analysis, and mechanical system design. She has conducted energy projects at facilities and campuses across the country and has led energy trainings through the Federal Energy Management Program. Ms. Cizik has a degree in Architectural Engineering and an MBA from the University of Colorado.


Note: I2SL did not edit or revise abstract or biography text. Abstracts and biographies are displayed as submitted by the author(s).