HVAC Embedded Fault Detection and Diagnostics
HVAC System Operation and Maintenance : Embedded Diagnostics vs. Manual Diagnostics
Smart equipment for commercial and residential HVAC that recognizes when it is failing or has failed, or when environmental conditions have drifted outside its optimum capability range, and can communicate that to personnel.
For many common faults, HVAC energy efficiency decreases before there is a noticeable change in occupant comfort. The building operator does not perceive an issue with the HVAC system. Fault detection and diagnostic systems (FDD) systems have been developed to alert the technician when an HVAC component either fails or experiences a drop in efficiency (Navigant Consulting, 2012).
Smart equipment for commercial and residential HVAC can now recognize when it is failing or has failed, or when environmental conditions have drifted outside its optimum capability range. Without this technology there is currently little or no feedback to the owner about the real-time condition and operation and energy use of rooftop equipment.
With an FDD system, operating parameters are compared against a reference and when the difference between the measured conditions and the reference exceeds a critical threshold, a fault is detected (Navigant Consulting, 2012). An algorithm is then used to diagnose the fault and the operator is alerted. Widespread adoption of FDD systems could save substantial amounts of energy if the equipment sent useful information to the owner’s representative. This technology is highly cost effective with a relatively low first cost and potentially 10% savings. This technology is available, but not widely used.
A further advance upon the theme of embedded diagnostics is that of self-correcting HVAC controls. These controls could detect, isolate, characterize, and correct faults associated with biases in temperature and relative-humidity sensors, incorrectly set signal to position outside-air dampers of an air handler to meet minimum ventilation requirements, hunting dampers, and controllers left in a state of manual control override when they should be in automatic mode. Advances in such controls are still under development. (N. Fernandez et. al., Pacific Northwest National Laboratory, "Self Correcting HVAC Controls: Project Final Report", December, 2009).
Energy Savings: 13%
Energy Savings Rating:
Limited Assessment What's this?
|1||Concept not validated||Claims of energy savings may not be credible due to lack of documentation or validation by unbiased experts.|
|2||Concept validated:||An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles.|
|3||Limited assessment||An unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline. |
|4||Extensive assessment||Additional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions. |
|5||Comprehensive analysis||Results of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications.|
|6||Approved measure||Protocols for technology application are established and approved.|