HVAC Embedded Fault Detection and Diagnostics

Summary

HVAC Embedded Fault Detection and Diagnostics

HVAC System Operation and Maintenance : Embedded Diagnostics vs. Manual Diagnostics

Synopsis:

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?

Level	Status	Description
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.

Details

HVAC Embedded Fault Detection and Diagnostics

HVAC System Operation and Maintenance : Embedded Diagnostics vs. Manual Diagnostics

Item ID: 163

Sector: Commercial

Energy System: HVAC--Sensors & Controls

Technical Advisory Group: 2010 HVAC TAG (#3)
Average TAG Rating: 3.1 out of 5
TAG Ranking Date: 06/29/2010

Technical Advisory Group: 2009 HVAC TAG (#2)

Technical Advisory Group: 2015-1 Commercial HVAC TAG (#11)
Average TAG Rating: 2.89 out of 5
TAG Ranking Date: 03/10/2015
TAG Rating Commentary:

There are applications where this would prove useful - specifically campus situations where a dedicated staff is available for the maintenance and operations of buildings. But it adds a lot of cost and complexity to systems. Someone has to be there to set up and monitor these systems and understand the output. In most buildings that person does not exist.
This strategy doesn't fit well in utility incentive programs -very difficult to verify savings and measure life.
I believe the concept to be sound, and a real market need. I am less aware of the state of existing products in this area and their ease of implementation and effectiveness in savings.
See the recent NIST report by Domanski, Henderson, and others. Excellent justification through lab studies and simulations.
I would only support an open source software and control system algorithm. There are too many proprietary systems out there that don't talk to each other or can't be understood by normal energy efficiency engineers or building owners.
These are essential for ongoing savings
Not much uptake at this point. ASHRAE is working on standards and the technology might gain more traction after those are released.
BPA first needs to develop a framework for quantifying the energy savings. Products continue to be offered by the marketplace, but currently a path does not exist to credibly quantify energy savings - a robust evaluation framework is needed. Also, many existing FDD solutions are not scalable, because products require too much building-by-building configuration.

Synopsis:

Baseline Example:

Baseline Description:
Baseline Energy Use: 10.5 kWh per year per sf

Comments:

Commercial buildings with electric heating and cooling have an EUI of 19.9 kWh/sf (Table D-DA5) of the CBSA. Buildings with no electric heating and cooling use only 9.4 kWh/sf, so a rough estimate of the heating and cooling electrical load is 10.5 kWh/sf-year.

One could assume that the efficiency of HVAC equipment is 10% lower than optimum due to components being out of calibration. According to PNL, operational faults are pervasive across the commercial buildings sector, increase energy costs by up to 30%. Types of failures include failed economizers, equipment operating during unoccupied periods, and simultaneous heating and cooling. Automated fault detection and diagnostic tools are being designed to eliminate these types of energy waste and are in the process of being transferred to the private sector (Katipamula, 2012).

Manufacturer's Energy Savings Claims:

Comments:

This is more like a strategy, requiring the building owner to allocate resources to maintain equipment more often and to specify and procure equipment with advanced FDD capability.

Best Estimate of Energy Savings:

"Typical" Savings: 13%
Low and High Energy Savings: 1% to 30%
Energy Savings Reliability: 3 - Limited Assessment

Comments:

Building operators or managers need to respond to identified problems. The magnitude of savings might not be apparent to the manager who weighs the savings versus the cost of the repair. The building owner needs to have the resources to respond to anomalies as they occur. Note that HVAC control systems are often provided with various alarms and alerts. The presence of diagnostics assists building operators to get equipment operating as designed as quickly as possible i.e. it not only alerts the operator to a malfunction, but also indicates the type of malfunction that is occurring. Correcting the equipment sooner might lead to a short term increase or decrease in energy consumption. Note that this is more of a strategy than an energy savings technology and could be handled through the preparation of procurement specifications that include all potentially useful alarm and alert options.

The US DOE Building Technologies Office assumes an energy savings of 13% based upon the assumption that an FDD system would maintain equipment efficiency 15% better than conventional methods of seasonal maintenance (Navigant, 2012). This value will be used as our "best estimate" of energy savings.

Energy Use of Emerging Technology:

9.1 kWh per sf per year What's this?

Energy Use of an Emerging Technology is based upon the following algorithm.

Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))

Technical Potential:
Units: sf
Potential number of units replaced by this technology: 715,696,366
Comments:

This technology could technically be used for virtually any conditioned commercial building space, so we start by examining the total of the entire conditioned commercial building stock in the Northwest. The numbers are taken from preliminary updated numbers from the 2013 update to the Commercial Building Stock Assessment (CBSA) using the estimates for 2014 (before the update was completed -- from early January, 2014) multiplied times the percentage of commercial space that is conditioned based on the 2009 CBSA. Electrical energy savings are maximized in that portion of the stock that has an electrically heated floor area. About 27.1% of the commercial building square footage is electrically heated. Therefore, the target market represents about 27.1% x 2,640,946,000 = 715,696,366 sf.

	Total Commercial Floor space	% Conditioned	Conditioned space
Source, units	(NEEA, 2014) (s.f.)	(NEEA, 2009 App C, Table C-GB4)	(s.f.)
	3,118,000,000	84.7%	2,640,946,000

Regional Technical Potential:
0.98 TWh per year
112 aMW
What's this?

Regional Technical Potential of an Emerging Technology is calculated as follows:

Baseline Energy Use * Estimate of Energy Savings (either Typical savings OR the high range of savings) * Technical Potential (potential number of units replaced by the Emerging Technology)

First Cost:

Installed first cost per: sf

Comments:

The American Council for an Energy-Efficient Economy (ACEEE) estimates $500 per unit.

Cost Effectiveness:

Simple payback, new construction (years): N/A

Simple payback, retrofit (years): N/A

What's this?

Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.

Comments:

This technology is highly cost effective with a relatively low first cost and potentially 10% savings.

Detailed Description:

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, could save substantial amounts of energy if the equipment sent useful information to the owner’s representative. The necessary capabilities are referred to as automated Fault Detection and Diagnostics (FDD).

Some of the problems that can affect the energy efficiency of Roof Top Units (RTUs) include:
. Insufficient evaporator airflow
. Condenser coil fouling
. Incorrect refrigerant charge
. Compressor valve leakage
. Liquid line restrictions
. Economizer damper failure
. Sensor failure/degradation

Standard Practice:

The standard practice for commercial rooftop air conditioners is lower-efficiency commoditized products sold as least-purchase-price solutions.

Development Status:

Use of alarms are commonplace. Automatic fault detection and diagnostics is a major step forward. Smart Monitoring and Diagnostic system are available (as of January 2013) but not widely purchased by building owners. Future work involves the development of self-correcting controls that automatically detect and optimally compensate for faults. Retrofitting these types of controls onto existing packaged units requires considerable expertise.

According to a Public Interest Energy Research (PIER) report, the ACRx Sentinel system is undergoing field tests.
A 2006 California Energy Commission report cited a field test, with participants including Automated Logic Co.

Non-Energy Benefits:

Less HVAC run-time. Reduced maintenance, and equipment should last longer.

End User Drawbacks:

The commercial rooftop air conditioner market is fiercely competitive, and dominated by lower-efficiency commoditized products sold as least-purchase-price solutions. Utility incentives are considered essential for moving the market to higher performance (ACEEE Report).

There may be building owners that only want to pay a service tech for the annual service and for failures, and not for minor adjustments. Without studies to demonstrate at least as much savings potential as tech service fees, there may be building owners that won’t see the value.

Manufacturers appear to offer onboard diagnostics only on high-end models.

Operations and Maintenance Costs:

No information available.

Effective Life:

Comments:

Better than the average RTU and about the same as a routinely serviced and maintained RTU. 15 to 25 years.

Competing Technologies:

Higher-end direct digital controls and energy management systems, as well as emerging dashboard systems.

Reference and Citations:

PIER, 04/04/2008. Public Interest Energy Research (PIER) Program Research Write-Ups 1997-2007
State of California

NEEA, 01/01/2014. Total Pacific Northwest Building Stock Based on Preliminary Numbers from the 2013 Update to the CBSA
Northwest Energy Efficiency Alliance
Special Notes: Preliminary Building stock square footages from the database for the 2013 update to NEEA's Commercial Building Stock Assessment.

CADMUS, 12/21/2009. Northwest Commercial Building Stock Assessment (CBSA): Final Report
Prepared by the CADMUS Group for the Northwest Energy Efficiency Alliance

James Braun, 04/19/2004. Final Report Compilation for Fault Detection and Diagnostics for Rooftop Air Conditioners
California Energy Commission

PIER, 07/26/2005. Automatic Diagnosis for Ailing Rooftop Air Conditioners
Public Interest Energy Research

James Braun, 10/12/2012. Automated Fault Detection and Diagnostics for Vapor Compression Cooling Equipment
Herric Laboratories/Purdue University

Siyu Wu, 07/26/2010. Multilevel Fault Detection and Diagnosis on Office Building HVAC Systems
University of California

Jiri Vass, 03/10/2010. Embedded Controllers for Increasing HVAC Energy Efficiency by Automated Fault Diagnostics
Automation & Control Solutions (ACS) Laboratories Honeywell

J Schein, 08/01/2003. Results from Laboratory Testing of Embedded Air Handling Unit and Variable Air Volume Box Fault Detection Tools
National Institute of Standards and Technology

Arch Energy, 08/25/2004. Rooftop Unit Diagnostics
Architectural Energy Corporation

Arch Energy, 08/25/2004. Web-Enabled Automatic Diagnostics
Architectural Energy Corporation

PIER, 08/03/2007. Advanced Automated HVAC Fault Detection and Diagnostics Commercialization Program Final Production Readiness Plan
Public Interest Energy Research

Arch Energy, 11/30/2006. AHU and VAV Box Diagnostics
Architectural Energy Corporation

Srinivas Katipamula, 09/26/2012. Building Systems Diagnostics Work at Pacific Northwest National Laboratory
Pacific Northwest National Laboratory

Navigant Consulting, 10/01/2012. Energy Savings and RD&D Opportunities for Residential Building HVAC Systems
U.S. DOE Building Technologies Office

Rank & Scores

HVAC Embedded Fault Detection and Diagnostics

2015-1 Commercial HVAC TAG (#11)

Technical Advisory Group: 2015-1 Commercial HVAC TAG (#11)
TAG Ranking: 16 out of 29
Average TAG Rating: 2.89 out of 5
TAG Ranking Date: 03/10/2015
TAG Rating Commentary:

There are applications where this would prove useful - specifically campus situations where a dedicated staff is available for the maintenance and operations of buildings. But it adds a lot of cost and complexity to systems. Someone has to be there to set up and monitor these systems and understand the output. In most buildings that person does not exist.
This strategy doesn't fit well in utility incentive programs -very difficult to verify savings and measure life.
I believe the concept to be sound, and a real market need. I am less aware of the state of existing products in this area and their ease of implementation and effectiveness in savings.
See the recent NIST report by Domanski, Henderson, and others. Excellent justification through lab studies and simulations.
I would only support an open source software and control system algorithm. There are too many proprietary systems out there that don't talk to each other or can't be understood by normal energy efficiency engineers or building owners.
These are essential for ongoing savings
Not much uptake at this point. ASHRAE is working on standards and the technology might gain more traction after those are released.
BPA first needs to develop a framework for quantifying the energy savings. Products continue to be offered by the marketplace, but currently a path does not exist to credibly quantify energy savings - a robust evaluation framework is needed. Also, many existing FDD solutions are not scalable, because products require too much building-by-building configuration.

2010 HVAC TAG (#3)

Technical Advisory Group: 2010 HVAC TAG (#3)
TAG Ranking: 7 out of 36
Average TAG Rating: 3.1 out of 5
TAG Ranking Date: 06/29/2010
TAG Rating Commentary:

2009 HVAC TAG (#2)

Technical Advisory Group: 2009 HVAC TAG (#2)
TAG Ranking:
Average TAG Rating:
TAG Ranking Date:
TAG Rating Commentary: