EDR_DesignBriefs_automatedmonitoring.pdf

energydesignresources

AUTOMATED MONITORING AND FAULT DETECTION

design brief

Summary

Commissioning, retro-commissioning, re-commissioning, and

automated monitoring and fault detection (also referred to as automated

commissioning) are all systematic methods of ensuring that a building

and its hardware perform to the level intended by the owner and design

team. Buildings that are running properly benefit from reduced

maintenance, quality indoor environments, and lower energy costs.

Using only energy savings, the median payback for retro- and re-

commissioning is less than a year and approximately five years for new

construction commissioning.6

As sensor technology, building control networks, and building

supervisory software have evolved into building automation systems

(BAS), better information about building performance has become

available to building operators. Most modern BAS offer alarm filters

that may be set for out-of-range conditions and detecting critical

component faults. An emerging use of these capabilities is the

application of sophisticated algorithms to detect hidden problems that

are usually discovered in a formal commissioning process. However,

commissioning and retro-/re-commissioning lack the advantage of

continuing to monitor and identify issues, which automated monitoring

offers. The automated process can be as simple as helping building

operators gather data or as powerful as actively testing the hardware and

conducting reprogramming and recalibrations. This Design Brief

discusses developments in research and commercially available

automated monitoring systems.

C O N T E N T S

Introduction 2

Benefits of Automated Monitoring 5

Fault Detection andDiagnostics 9

FDD Detailed Example 14

Automated MonitoringPackages 17

The Future of AutomatedMonitoring 23

Conclusion 24

Glossary 25

For More Information 26

Notes 27

Automated monitoring provides

continuous monitoring of building

energy systems and can alert a

facility manager to performance

or comfort issues, saving time

and money.

PAGE 2 AUTOMATED MONITORING AND FAULT DETECTION

Introduction

Building commissioning is the systematic process of ensuring that a

building’s systems are designed, installed, and tested to perform

according to the design intent and the building owner’s operational

needs. The commissioning process can be applied to new and existing

buildings and covers the building envelope, plumbing, and all energized

systems (lighting, HVAC, refrigeration, life-safety, occupant transport,

and specific processes). Commissioning is an iterative process of

communication, observation, actively testing components and systems,

and recording results. Traditionally, it has been conducted over a set

time period by a team of specialists who understand the design,

installation, and operation of these systems. If applied to existing

buildings, it is often called retro-commissioning (first application) or re-

commissioning (second and subsequent applications).

The commissioning of new buildings is most effective when considered

throughout the planning, design, construction, and post-occupancy

stages. Integrating commissioning into a new building project provides

the opportunity for the best initial performance, which the owner can

use as a guideline throughout the life of the building.

Post-occupancy commissioning (including retro-commissioning and re-

commissioning) usually are performed because some aspect of building

performance, such as occupant comfort or energy use, has exceeded the

baseline performance that should be achieved. Post-occupancy

commissioning is the process of systematically re-evaluating the

performance of the building systems. Simply tuning the building

controls is often a cost-effective means of returning the building to its

design performance. But commissioning of existing buildings often

identifies components or systems that should be repaired or replaced.

Repair and replacement offer the opportunity to install higher efficiency

equipment or improve operations by improving the controls for systems.

Often comfort is improved, and energy use or demand is reduced.

A key limitation to commissioning and retro-/re-commissioning is that

each one is a periodic service, and building performance usually tends to

drift away from the design baseline over time. Also, retro-/re-

PAGE 3AUTOMATED MONITORING AND FAULT DETECTION

commissioning are usually not considered until a problem is significant

enough to warrant action. Over time, the slow deterioration in

equipment and changes in control systems, specifically the HVAC

system, adds up to higher energy costs and degrading comfort. Changes

in building use, including increases in occupant density, personal

computers, copiers, and other energy-consuming office equipment, may

also adversely affect performance.

Degradation in performance is often due to budget shortfalls for

equipment repair and replacement, and shortages of trained operators.

In turn, equipment life may be shorter than expected because operators

must spend a greater portion of their time addressing problems that

cause comfort complaints rather than underlying equipment problems.

They simply don’t have enough time to manually analyze trend data and

inspect equipment on a routine basis. And, since it’s not practical to

have a commissioning team on hand at all times, an outsider’s

perspective on performance degradation and how changes in building

use affect energy use and comfort is not available.

As mentioned, due to the evolution of BAS, better information about

building performance has become available to building operators. Most

modern BAS offer alarm filters for detecting critical component faults

and sophisticated algorithms for finding hidden problems that are

usually discovered in a formal commissioning process. Some in the

industry have called this “auto-commissioning” because it automates

some, but not all, of the processes in traditional commissioning.

Automated commissioning is continuous or periodic monitoring of

building sensor and control points, applying algorithms that detect

faults in building systems, and notifying operators that faults exist.

However, it does not necessarily involve commissioning experts and

relies on traditional commissioning functional tests.

To acknowledge these differences, this paper has adopted “automated

monitoring” to describe technologies that are more reliant on BAS.

Table 1 shows trends in the evolution of building automation systems

and the resulting higher quality information.


Source: Architectural Energy Corporation

“Faults” are conditions that are outside of design intent and may include

conditions that waste energy, increase electric or natural gas demand,

and may result in comfort complaints. In addition to detecting faults,

automated monitoring systems may also diagnose faults and provide

information about possible causes.

Automated monitoring can provide operators with information that

allows them to focus on the root causes of comfort complaints and energy

waste. It also can be a very valuable adjunct to retro-/re-commissioning

projects by providing insight into equipment deficiencies at the

beginning of the project. Table 2 summarizes the key characteristics

associated with commissioning, retro-commissioning, re-commissioning,

and automated monitoring.

Level Building ControlDescription

Control Access(Local, Remote)

Control SystemCharacteristics

Operator InteractionWith Controls

Commissioning Technology

1 Independent,separate control ofcomponents and/orsystems

Local No or little datastorage

Manual control ofcomponent andsystem operations

On-site personal observation;use of pre-functional checklists and functionalperformance tests

2 Integration ofcontrol under on-site supervisorysoftware

Local Ability to store anddisplay data

Automated control ofon/off schedules andsetpoints

Level 1 plus local humananalysis of displayed data tofind operations problems

3 Level 2 plusconnection viaphone line

Local and RemoteComputerTerminals

Level 2 plus abilityto apply filter rule-sets to generateautomatic alarms

Level 2 plus simplealarms and remoteaccess

Level 2 plus remote access andautomatic alarms forequipment protection and/oroccupant comfort

4 Level 3 plusInternet technology

Level 3 plusalarms to remotepagers, cellphones, andemail

Level 3 plusembeddeddiagnostics in localcontrollers and/ordiagnostics atsupervisory level

Level 3 plusinformation to assessmaintenancerequirements

Level 3 plus diagnostic reportsfor fault detection atcomponent and/or system level

5 Level 4 withoutside input forutility demandresponse (weatherand loadinformation)

Same as Level 4 Level 4 plus built-inoptimization basedon internal loadsand externaldemand response

Level 4 plusautomatic loadmanagement andinformation to assesspredictivemaintenance

Level 4 plus predictive loadand maintenance models

Table 1. Evolution of Building Automation Systems


Benefits of Automated Monitoring

Automated monitoring systems can provide information that benefit

building performance in the areas of indoor air quality, thermal

comfort, energy cost savings, labor savings, and risk mitigation.

Incorporating automated monitoring features in a building also may

qualify for credits under the U.S. Green Building Council’s (USGBC)

Leadership in Energy and Environmental Design (LEED) Green

Building Rating System™.

Indoor Air Quality and Thermal Comfort

When a component fails in the HVAC system, often the building

operators and occupants are not aware that anything has changed. For

Table 2. Matrix of Commissioning Characteristics

Commissioning Retro-Commissioning Re-Commissioning Auto-Monitoring

Application New Construction Existing buildings that havenever been previouslycommissioned, or if buildingage or modifications render commissioning plans obsolete

Existing buildings thathave beencommissioned orretro-commissioned

All applications

Timing As early as possiblei.e. pre-design

Occurs in response tounder-performance orproblems in the buildingsystems

Occurs periodically orin scheduled intervalsas part of the O&M, orin response to specificoperating issues

Any time afterbuilding systems areinstalled andoperational

Purpose Ensures buildingsystems will performoptimally

Solves problems thatprevents buildings fromperforming optimally

Ensures building isstill performingoptimally, maintainslevel of previouscommissioning

Continuouslymaintains optimalperformance

Frequency Once during theinitial design andconstruction

Once, as needed due toage; 10-15yrs

Every 3-5yrs Once installed,provides continualcommissioning for thelife of the building

Cost6 Varies with size andcomplexity of systems:$0.50 to $3.00/ft2,median is $1.00/ft2

$0.05-$0.40/ft2, median is $0.27/ft2

Costs will be similarto retro-commissioning

Too large a range offunctions and costs tocurrently compare. Haspotential to be mostcost effective method.

Benefit6 $1.00/ft2 energysaving with a medianpayback of 4.8 yrs.One time non-energybenefit = $1.24/ft2

$0.27/ft2 for 15% energysavings and payback of0.7 yrs, one time non-energy benefits = $0.18/ft2

Similar to retro-,depending onfrequency

Similar to retro- andre-commissioning withcontinuous benefits forthe length of operation.

Source: Architectural Energy Corporation


example, if an outdoor supply air (OSA) damper seized in the closed

position or was closed by a technician to address an occupancy

complaint, fresh air would not be delivered to occupied spaces. This

condition may reduce energy costs because the proper amount of outside

air would have not been heated or cooled, but this is clearly at the

expense of good indoor air quality. Also, during periods when the outside

air temperature is within the economizer range, free cooling would not

be available. Automated monitoring can detect this problem quickly and,

in some cases, provide a diagnosis of what caused the problem.

Energy Cost Savings

Automated monitoring can expose a problem long before a serious

malfunction occurs. If an outdoor supply air (OSA) damper seized in

the open position, during cooler weather the boiler or heater would

compensate for the added cold air and the indoor air temperature would

remain within setpoint limits. During winter months, however, the

ambient temperature would drop and the hot water coil or heater might

not have enough capacity to maintain the set point, creating

uncomfortable room temperatures. At this point, occupants would

complain and building maintenance staff would eventually become

aware of the problem. During extremely cold temperature conditions, it

is possible that coils might even freeze. Significant energy waste can

occur for months without automated monitoring.

For existing buildings, retro- or re-commissioning typically results in a

reduction in energy use of 10 percent to 30 percent (see retro-

commissioning sidebar) with payback periods that are often less than

one year. The energy saved using automated monitoring is predicted to

be similar to retro- or re-commissioning. The initial hardware, software,

and setup costs for an automated monitoring system may be equivalent

to that of a retro- or re-commissioning project.

An automated monitoring system, if used properly, enables building

operators to create persistence in savings for energy, labor, and

maintenance during the life of the facility. Finally, indoor environments

for building occupants can be more reliably maintained, which help

mitigate indoor air quality (IAQ) issues and associated costs.

Retro-Commissioning Cost SavingsRetro-commissioning of existing

buildings reduces energy use by

anywhere from a few percent to

more than 60 percent of pre-retro-

commissioning consumption, with

most savings falling into the range

of 10 percent to 30 percent.1

In 2004, Lawrence Berkeley National

Laboratory, Portland Energy

Conservation Inc., and the Energy

Systems Laboratory at Texas A&M

University developed the largest survey

to date on the costs associated with

commissioning on commercial buildings.

The reseachers reported, “For existing

buildings, we found median

commissioning costs of $0.27/ft2,

whole-building energy savings of

15 percent, and payback times of

0.7 years.

These results are conservative insofar

as the scope of commissioning rarely

spans all fuels and building systems in

which savings may be found, not all

recommendations are implemented, and

significant first-cost and ongoing non-

energy benefits are rarely quantified.”6


Labor Savings and Risk Mitigation

The most tangible benefit of automated monitoring is energy cost

savings, but there are other benefits that are not as obvious. One such

benefit is labor cost savings, in the form of more efficient diagnosis and

maintenance. Automated monitoring systems have the potential to not

only find a problem with minimal or no human intervention, but to also

detect problems earlier. When problems are detected early, maintenance

staff are able to directly address faults before they have existed for long

periods, which results in better performing systems.

Constantly monitoring the energy systems also may mitigate the risk

that a major failure will occur, because some catastrophic failures result

from malfunctions going unnoticed. In some cases, major equipment

failures can be completely avoided, or downtime can be scheduled for

repairs or replacements instead of being forced into emergency outage

situations. Long term equipment condition can be tracked by an

automated monitoring system, allowing equipment replacements and

maintenance work to be forecasted.

LEED Accreditation

For building owners pursuing accreditation under the USGBC LEED®

rating systems, automated monitoring systems may help qualify projects

for credits under the Energy and Atmosphere (EA) and Indoor

Environmental Quality (EQ) categories. For the New Construction

(LEED-NC) rating system, automated monitoring systems could apply

to the following.

� EA prerequisite #1: Fundamental Commissioning of Building

Energy Systems and EA credit #3: Enhanced Commissioning -

designing and implementing an automated monitoring system

should support the commissioning activities for a new facility and

help qualify for this prerequisite and credit.

� EA credit #5: Measurement and Verification - an automated

monitoring system may support on-going accountability of energy

consumption (required for at least one year) under this credit.

� EQ credit #1: Outdoor Air Delivery Monitoring - if carbon dioxide

and air flow data points are permanently monitored and provide

continual feedback into the automated system, a credit is achievable.

A visual or audible alert is required when conditions vary by more

than 10 percent.

The Existing Buildings (LEED-EB) rating system has similar credits

under the EA and EQ categories.

� EA prerequisite #1: Existing Building Commissioning - designing

and implementing an automated monitoring system as part of retro-

commissioning an existing facility supports this prerequisite.

� EA credit #3.3: Building Operations and Maintenance - Building

Systems Monitoring – this requires continuous monitoring, alarms

that identify issues, and a system for responding to repairs. These

requirements align with the primary goals of automated monitoring

systems.

� EA credit #5.1-5.3: Performance Measurement - Enhanced Metering

– this requires continuous metering during a selected performance

period of various building energy and water consumption with

measures in place to show improved performance. Automated

monitoring systems can be designed to monitor the performance of

most systems listed in the checklist including cooling loads, chilled

water system efficiency, air volume, air and water economizers, and

variable frequency drive operation.

� EA credit #6: Documenting Sustainable Building Cost Impact -

information from automated monitoring systems also can be used to

meet the requirements listed for this credit.

� EQ credit #1: Outdoor Air Delivery Monitoring - if carbon dioxide

and air flow data points are permanently monitored and provide

continual feedback into the automated system, credit under the EQ

credit #1 is achievable.



� EQ credit #7.2: Thermal Comfort: Permanent Monitoring System -

this credit requires measurement and trending of temperatures,

relative humidity, and CO2 or air speed at locations selected

according to the impact on occupant comfort. Automated

monitoring systems can be designed to handle these tasks.

Fault Detection and Diagnostics

Considered the cornerstone of automated monitoring, fault detection

and diagnostics (FDD) is the process by which malfunctions,

degradations, and broken equipment is recognized and diagnosed by

software. A system that has chronically high supply air temperatures

during the summer might have a stuck damper. In the absence of FDD,

a technician must visually inspect the outside air dampers or review the

time series plots of the outside, return, mixed, and supply air

temperatures and reach a correct diagnosis. FDD software can run the

same data through an algorithm and reach the same conclusion quicker.

Unlike traditional commissioning where a building is monitored for a

discrete amount of time, automated FDD is continuous and can ensure

the proper function of building systems as long as it is in place. Human

intervention is still needed to carry out repairs and maintenance.

However, once a repair is completed, the FDD system will automatically

verify that it is functioning correctly.

Although not yet commercially available, FDD tools with active control

could further react to the fault by taking action. Most malfunctions are

minor and either reduce efficiency or cause poor IAQ. If the problem

can be fixed through the BAS, such as an out-of-calibration sensor, the

FDD controller could recalibrate the sensor and report the adjustment.

If a fix through the BAS is not possible, an alternative may be to bypass

the malfunctioning sensor and run the system at a slightly reduced

efficiency until the problem is corrected. The last scenario would occur

when either safety is compromised or the HVAC system could suffer

catastrophic failure. In this case, the FDD controller would take the

appropriate action and issue an alarm to the building operator. Figure 1

shows a generic FDD process decision tree.


Detecting Faults

Regardless of the fault detection method used, faults are detected when

the comparison residual (actual value minus predicted value), exceeds a

predefined threshold. Not all values come directly from readings, some

variables are either calculated or characteristic values, such as outside air

quantity or coefficient of performance for an air conditioner. Regardless

of the source of the variable, it is important to use a dynamic model for

predicted values. HVAC systems are inherently dynamic due to

changing indoor and outdoor conditions. Using a fixed value as a

comparison will result in either too many or too few faults being

reported. For example, if facility staff were measuring efficiency and

comparing it to a fixed minimum value, the result would not be accurate

because efficiency changes with input conditions. For this reason, the

detection algorithm should run a dynamic model. This could be as

simple as using a formula to change the threshold based on inputs or a

real time simulation of the whole system.

Building System/Component

Fault Detection

Passive FaultDiagnosis/Isolation

Fault Evaluation

• Safety• Availability• Energy/Cost Impact• Comfort• Environmental• Impact

No ActionRequired

Decision

Request a Repairand Continue

Reconfigure the Controls

Tolerate?

ReconfigureControls?

Continue toOperate?

Alarm/Shutdown

Fault

Fault Diagnosed

No Fault

ProactiveDiagnosis

Mea

sure

men

ts

Pro-ActiveDiatnosis for

Fault Isolation

Tolerate

No

No

No

Operate

Reconfigure

Figure 1. Generic Automated FDD Process Tree

Source: Portland Energy Conservation, Inc.


Diagnosing Faults

Diagnosing faults is a much more sophisticated process than detection.

Detection is as simple as fault or no fault, diagnosis may require an

analysis of multiple faults (passive diagnosis), or require manipulation of

the system itself (active diagnosis). Many times a fault is detected but its

cause cannot be determined without observing the system through a

wide range of conditions or modes. Using the proactive measure, modes

can be forced and a conclusion reached in a relatively short amount of

time. Passive diagnostics may take considerable time for the system to

cycle through the required conditions or modes on its own.

The cause of some faults can be determined as soon as they are

discovered. For example, if a large pressure drop is found across the air

filter, the diagnosis would be a clogged air filter (assuming the sensor is

functioning properly). On the other hand, triggered faults that are a

result of calculated values typically need further testing to determine

their origin. For example, the monitoring system might detect a

potential sensor error, but is unable to pin point the error among three

different sensors – return air, mixed air, and outside air. A proactive

system could wait until the building is unoccupied to force modes that

reveal the diagnosis. Through the BAS, the diagnostics program could

initiate 100 percent outside air and compare both mixed air and outside

air, then switch the dampers for 100 percent return air, and compare the

return air and mixed air. By isolating the different sensors and

comparing them, the faulty sensor should reveal itself. Figure 2 shows a

proactive FDD decision tree for a faulty sensor.


A malfunctioning sensor does not always need to be replaced. Sensors

may be un-calibrated, drifting, or installed incorrectly. By reviewing the

backlog of data on the sensor, the actual issue can sometimes be

determined and the appropriate action taken. A fully automated

monitoring system may be able to recalibrate the sensor and give a

report without ever needing the assistance of a technician.

Proactive DiagnosticsTemperature Sensor Problem

TemperatureSensor

Problem

SequentialOperation

Close Outdoor-AirDamper Completely

Shut (100%Recirculation)

Close Return-AirDamper Completely

Shut (100% Outdoor Air)

Wait for Conditionsto Reach

Steady-State

Wait for Conditionsto Reach

Steady-State

Is Mixed-Air Temperature =Return-Air Temperature

Is Mixed-Air Temperature =Outdoor-Air Temperature

Equal Equal

NoNoMixed-Air andReturn-Air

Temperature Sensors OK

Mixed-Air andOutdoor-Air

Temperature Sensors OK

If BothTests Fail

Problem: Outdoor-AirTemperature Sensor

Problem

Problem: Return-AirTemperature Sensor

Problem

Problem: Mixed-AirTemperature Sensor

Problem

Figure 2. Possible Decision Tree to Isolate Faulty Temperature Sensor



Verifying HVAC Programming and Schedules

Automated tools can monitor system schedules over long periods of

time and detect changes that waste energy. It is not uncommon for

operational schedules to be manually overridden for special events or

maintenance. If the BAS does not have a function to return the schedule

to normal operation, the over-ride condition may persist for weeks or

months. Simply reporting each over-ride condition may save significant

amounts of energy by allowing a supervisor to see and correct changes

that could be overlooked.

Data Handling and Documentation

Apart from the labor saving benefits that fault detection and diagnosis

provides, valuable time is also saved on data management. Part of the

automation process involves the management and conversion of data into

a comprehensible format. This can be as simple as interpreting and

exporting into a spreadsheet or as complex as a graphical interface capable

of performing many advanced functions with the data. Data storage and

data mining are key features that allow for easy review of historical trends.

Additionally, many of the current automated monitoring systems provide

access to building information via the Internet, which produces time

savings for facility managers and staff, especially when multiple building

locations or campus-wide sites are involved.

Automated documentation is another advantage of automated

monitoring. Automated tools are capable of creating performance and

maintenance reports as well as managing some types of commissioning

documents. Performance reports can track deficiencies and report

improvements. A major survey of commissioning providers suggested

that key aspects for automated monitoring systems were tracking and

creating standardized commissioning reports through automation.8


FDD Detailed Example

Diagnose Faulty Outside Air Damper

Faulty dampers and valves in air-handling units (AHU) are difficult to

identify. A leaky hot water valve will increase the temperature of the air

entering the cooling coil, but this is compensated for by increased

mechanical cooling. The same thing occurs with damper problems: an

incorrect mixed air temperature due to excessive or inadequate outside

air can most times be compensated for by increased heating or cooling.

Since IAQ is generally not affected, faults in these components can go

unnoticed for years. Valves and dampers consist of many different

components and it is beyond the capabilities of current software to

distinguish what type of malfunctions occurred. Simply identifying a

fault will alert users to a damper or valve malfunction.

One way to diagnose a faulty outside air damper is to monitor either the

fan power or pressure drop across the damper. The pressure drop and fan

power will be different for every AHU, so an initial “training” period is

required to characterize the operation. Using this method, a simple look-

up table could be created that relates outside air fraction, damper position,

and fan power or pressure drop across the damper. Data for this table

would be collected by first setting the system to normal operation mode

with the outside air damper (OSAD) fully closed. Then, allow the return

air and exhaust air dampers to operate normally and the system to reach

equilibrium, and record the three inputs. The next step is to record the

measurement again, this time with the damper open 10 percent and repeat

the process in 10 percent increments until the damper is 100 percent open.

The next stage is to characterize the system for a stuck open and stuck

closed damper. To do this, the process is repeated as before with the system

operating normally except the damper is forced open or shut. The return

air and exhaust air dampers should operate as if the OSAD was in the

correct position. For instance, if the system was calling for full outside air,

the return damper would be shut and the fan would be working against a

large pressure drop causing more power to be drawn. If the damper was

stuck open, then the power draw would be lower. The system must be

characterized first to be able to determine the exact meaning of the power

differences. A typical look-up table might look like Table 3.


As shown in Figure 3, the first step in diagnosing a potential damper

problem is to validate the sensors to ensure they are reading correctly.

Then, confirm that the damper position is correct by comparing it to

the expected damper position. The expected damper position can be

determined based on outside air temperature and the mode of the AHU.

If the system is operating appropriately, the next step is to use the look

up table to confirm that the fan power corresponds to normal operation.

If it is not, a higher power draw in this example corresponds to a stuck

closed damper, and a lower draw corresponds to an open damper.

Once the FDD system has made a diagnosis, it can react in different

ways depending on how sophisticated and well integrated it is with the

HVAC system. If the FDD system is capable of being active, it can make

changes, such as changing schedules or recalibrating sensors. Some

faults, like the damper example, cannot be fixed through the controller

and require a physical repair. In a system where the FDD cannot make

changes, creating a fault alarm is the only response.

Table 3: Lookup Table for Diagnosing Damper Faults, Created by Actively Calibrating the Damper System8

10 0.15 1,550 0.05 1,560 0.15 1,500

20 0.25 1,450 0.08 1,600 0.25 1,400

30 0.40 1,350 0.15 1,625 0.40 1,300

50 0.60 1,250 0.20 1,650 0.60 1,200

70 0.75 1,150 0.40 1,750 0.75 1,100

100 1.00 1,000 0.70 1,800 1.00 1,000


Outdoor AirDamperSignal

(% Open)

Normal Operation Outdoor Air DamperStuck Fully Closed

Outdoor Air DamperStuck Fully Open

Outdoor AirFraction

Supply FanPower

Consumption(Watts)

Outdoor AirFraction

Supply FanPower

Consumption(Watts)

Outdoor AirFraction

Supply FanPower

Consumption(Watts)


Is Actual Pressure

Drop and Power Consumption = Expected

Pressure Dropand Power

Consumption?

No

No

Yes

No

Correct

Good

Equal

No

Yes

Validate SensorMeasurements

Are SensorMeasurements

Good?Problem: Sensor Problem

Is Outdoor-AirDamper Signal

Correct?

Lookup Table forNormal Operation

Lookup Table forFaulty Operation

Is Actual Pressure

Drop and Power Consumption = Expected


Consumption?

Is Actual OAF =Expected OAF?

No

Problem: Unknown DamperProblem

Problem: Damper Problem

OK: OA Damper Operation OK

Problem: Control orControl Code

OAF is OK, but not the


Consumption

Figure 3. Decision Tree to Detect and Diagnose Outdoor Air Damper Faults



Automated Monitoring Packages

A number of public and private organizations have been actively

working to develop semi- and fully automated monitoring packages.

Summaries of several programs are provided. It is important to note that

some are available commercially, some are under development, and

others are under research. Additional information about the

organizations is shown in the For More Information section or by

footnote references provided in the Notes section.

ABCAT

The Automated Building Commissioning Analysis Tool (ABCAT),

developed by the Energy System Laboratory at Texas A&M University,

uses existing hardware in a fully commissioned building to achieve a

baseline measurement for operational energy use. During the calibration

period, the program is running its own simulation model; at the end of

that period, the mean error is subtracted to further calibrate the model.

It then monitors the building and compares the actual inside air quality

and energy use to the calibrated model. When the two values are not

synchronized, a fault is reported by the system.4

ACRx® Sentinel

Field Diagnostics Services Inc. created the ACRx® Sentinel package to

diagnose faults in small commercial air-conditioning units. The Sentinel

uses custom hardware installed in packaged-HVAC units to monitor

and transmit data to a web server via a wireless modem. The software

analyzes refrigeration and air-side data on a daily basis and reports faults

on a web page, including estimated wasted energy costs.9 The Sentinel

is available for retrofit applications and is likely to be available as an

OEM (original equipment manufacturer) feature that is sold to HVAC

companies within the next few years.


APAR and VPACC

The Air-handling unit Performance Assessment Rules (APAR) is an

expert set of rules for fault detection in air handling units developed and

published by National Institute for Standards and Technology (NIST)

(ASHRAE, 2001). The rules apply to single duct, variable- or constant-

volume air-handlers with hydronic heating and cooling and economizers.

APAR uses control signals and occupancy schedules to identify the mode

of AHU operation. Each mode has a subset of performance rules that are

evaluated using BAS sensor data. These modes of operation include

heating, cooling with outdoor air, mechanical cooling with 100 percent

outdoor air, mechanical cooling with minimum outdoor air, and

“unknown”, where the condition of the valves and dampers do not

correspond to an identified mode. The rules are suitable for

incorporation into AHU-controller hardware or use in a BAS supervisory

computer. The rules have been tested in hardware manufactured by

Alerton, Automated Logic, Johnson Controls, Delta Controls, and

others. An expanded version of the rules is used in the ENFORMA‚

Building Diagnostics software, which is referenced in this section.

The VAV-box Performance Assessment Control Chart (VPACC) method

was also developed and published by NIST. This method is based on a

widely used statistical method used in manufacturing to detect anomalies

in manufacturing processes. The VPACC algorithms are compact and

may be embedded in VAV-box controllers or used in supervisory control

software. The rules have been tested in hardware manufactured by

Alerton, Automated Logic, Johnson Controls, Delta Controls, and others.

CITE-AHU

CITE-AHU is a retro-commissioning tool developed from a joint effort

between NIST and CSTB, the French Scientific and Technical Centre

for Building. Designed specifically for AHUs, the program uses APAR

algorithms. CITE-AHU depends on the existing hardware in a building

and taps into the BAS for its interface. By connecting directly to the BAS,

CITE-AHU can perform active tests to force different modes. This

allows the program to more aggressively pursue faults without waiting for

them to happen.3


DABO

Diagnostic Agent for Building Operators (DABO) was developed at the

CANMET Energy Technology Centre-Varennes in Canada. DABO

requires a BAS because it actively monitors and controls the HVAC

system with four different modules.

Currently, the Diagnostic Agent module is the only part available for

commercialization. The Diagnostic Agent uses expert systems and

pattern recognition to monitor, diagnose, and report faults. The

Adaptive Controller monitors and controls the sub-systems of the

HVAC system, such as VAV boxes and AHUs at optimal levels. The

Building Energy Agent uses inputs from the Diagnostic Agent and the

Adaptive Controller to predict performance and optimize set points.

The Building Maintenance Agent uses outputs from the Diagnostics

Agent to create a maintenance schedule report. The last module in the

circle is the Building Commissioning Agent, which is the active part of

DABO. Using the information from the Diagnostic Agent, it runs a

series of tests and actively changes settings based on the results.5

EffTrack

EffTrack, developed by Efficiency Technologies, Inc. is an automated

efficiency and diagnostic web-based service focused on chiller, boiler,

and plate exchanger efficiency and trending. EffTrack uploads data from

an existing BAS and/or additional monitoring equipment to its servers

and processes the data to provide facility managers the ability to

document, monitor, evaluate, and manage chiller system performance.

Efficiency Technologies has announced plans for future enhancements

that will include advanced chiller charting, internationalization (metric

units), diagnostics, and automated data collection for boilers and plate

exchangers, water treatment analysis, screw chillers, steam driven

chillers, evaporator condensers, air-cooled and rooftop units, air

handling units, and tower systems.


ENFORMA® Building Diagnostics

ENFORMA Building Diagnostics (BD), developed by Architectural

Energy Corporation, is automated fault detection and diagnostics

software that runs on Tridium’s NiagaraAX BAS platform. The

ENFORMA software uses trend data from the underlying BAS,

processes it once a day, and stores and reports the faults for air-handlers,

chillers, cooling towers, and related equipment. The results can be

accessed using commonly available web browsers. ENFORMA BD

capabilities include a customizable graphical display of the data to

confirm faults detected by the system. Based on the duration of the

faults, the urgency level is displayed as red, yellow, or green in a graphic

maxtrix with days of the week in columns and building components in

rows. The program can be installed on a local or remote NiagaraAX

system, allowing managers and service personnel to remotely track

multiple building locations.

Information Monitoring and Diagnostic System (IMDS)

IMDS is a research system developed by Lawrence Berkeley National

Laboratory. The IMDS archives measurements from high-quality

sensors every minute. It includes a powerful data-visualization tool,

which can be used on-site or accessed via the Internet. The IMDS has

been used to identify and correct a series of control problems in a

demonstration building. It has also allowed the operators to make more

effective use of the building control system, freeing up time to take care

of other tenant needs. The operators believe they have significantly

increased building comfort, potentially improving tenant health and

productivity. The reduction in the time required to operate the building

is worth about $20,000 per year. A control system retrofit based on

findings from the IMDS is expected to reduce annual energy use by 20

percent, saving more than $30,000 per year. The project has also

evaluated simple chiller models for fault detection, concluding that they

can be used as references to monitor operation and detect faults. The

ability of the IMDS to measure cooling load and chiller power to within

one percent accuracy and with a one-minute sampling interval permits

the detection of faults that would otherwise be missed.


INFOMETRICS

Infometrics, developed by Cimetrics, is a remote monitoring service

using hardware and software that access data from the underlying BAS.

Cimetrics personnel analyze the data to find and diagnose faults.

Quarterly reports are created for the client with an energy use analysis,

mechanical system performance analysis, and a set of operational

recommendations prioritized by savings.2

PACRAT

Performance and Continuous Re-Commissioning Analysis Tool

(PACRAT) is an automated monitoring tool created by Facility

Dynamics. PACRAT taps into the existing BAS trend logs to monitor

and analyze the performance of the HVAC system. PACRAT has

three modules:

� Bass (data collection module)

� Expert (analysis and diagnosis module)

� Viewer (user interface)

The Bass module’s purpose is to connect to the building and to create

trend logs of appropriate data on a local server. The data are downloaded

periodically and analyzed using the Expert module. The Expert module

completes the analysis and diagnosis, and passes the processed

information on to the Viewer. The Viewer is a user-friendly interface

where the faults are categorized by importance. Faults with high

estimated energy waste are at the top of the list of suggested repairs.

Along with fault detecting and reporting, PACRAT can meter energy

use to maintain two running baselines for before and after comparison

of savings based on current utility rate schedules. Users are provided

with a real time reading of energy and unrealized energy savings.7

Rooftop Diagnostician

Developed at Pacific Northwest National Laboratory (PNNL), which is

operated by Battelle for the U.S. Department of Energy, this tool allows

facility staff to determine the cause of a malfunction in a rooftop unit or

to monitor performance in order to optimize regularly scheduled


maintenance. Rooftop Diagnostician provides fast and effective

diagnostics for HVAC units in commercial buildings, allowing staff to

better monitor the HVAC system to provide optimal performance.

The Rooftop Diagnostician attaches directly onto the HVAC unit and

provides real-time web-based performance information. The Rooftop

Diagnostician is available for licensing from Battelle and provides the

following. 10

� Supports heat pumps and dual fuel systems

� Detects low fresh air supply to prevent “sick” buildings

� Features a web-enabled display so no special software is needed

� Detects high energy use and control failures

� Provides real-time information that permits service analysis

� Collects performance data from three months to five years.

Whole Building Diagnostician

The Whole Building Diagnostician (WBD) was created by PNNL,

which is operated by Battelle for the U.S. Department of Energy.

WBD uses a building’s own data collection capabilities, when possible,

to funnel data into one of two modules: the Whole-Building Energy

module (WBE) and the Outside Air Economizer (OAE) diagnostics

module. The WBE monitors energy consumption and displays the

results on a graph in the form of an energy index. The index represents

the ratio of expected energy use to actual energy use. The expected

value comes from an internal empirical model that takes into account

factors such as time of day and weather. The OAE uses a limited

number of the sensor and control outputs on the air handling unit to

detect roughly 20 common errors. The errors are then color coded

based on severity and reported to the user. It is available for licensing

from Battelle.11


The Future of Automated Monitoring

Areas for Improvement

Automated monitoring and specifically FDD are still under substantial

development. Current products have already proven to be valuable

commissioning and maintenance tools, though installed systems are

few. One of the reasons for the lack of market presence is public

awareness, although technical information and case studies on

automated monitoring are becoming more prevalent. With increased

awareness and usage, automated tools and systems will become more

sophisticated and cost effective.

In five to 10 years, it is foreseeable that FDD tools will be integral to

building energy and control systems. Similar types of self-diagnostics are

standard equipment in the aerospace industry, power plants, and most

modern vehicles. One way to accelerate market adoption of this technology

is to embed the FDD software into the HVAC component controllers or

the BAS. Since most new buildings already use some sort of BAS, including

FDD on all new systems would lower the prices considerably.

Tools also could be developed to make automated monitoring and FDD

fully comprehensive across all building systems. The current focus is on

HVAC systems because the faults are most prevalent and the hardest to

detect. Lighting also provides an opportunity for FDD, because it has a

significant impact on energy consumption and many lighting systems

rely on control strategies to ensure efficiency. A comprehensive FDD

system could monitor the HVAC, lighting, water, and other essential

building systems that depend on programs or schedules to control use.

Current Development

As noted above, many different organizations are developing automated

monitoring tools, each with a slightly different focus. Most products are

focused on one or more major HVAC components, with the intent of

expanding the scope to create a comprehensive analysis tool that can be

used to detect and diagnose faults throughout the whole HVAC system.

The details of research and development by private organizations are

closely guarded. However, public groups such as CANMET Energy

Technology centre in Canada, NIST, and Annex 40 readily announce

current progress and future development.


Conclusion

Lack of proper commissioning, inexperienced operators incapable of

handling complicated building controls, and insufficient maintenance,

lead to reduced equipment life and increased operating costs.

Commissioning, re-commissioning, and retro-commissioning require

qualified commissioning personnel for periodically gathering, reviewing,

and documenting performance data. After traditional commissioning has

been completed, the beneficial effects often begin to dissipate.

On the other hand, automated monitoring provides continuous

feedback on building performance and affords the opportunity to

reduce labor requirements and create energy savings. Whether the

installed automated monitoring system is an active or passive FDD

system, nearly all HVAC systems will realize better performance.

Many hurdles still exist for this industry. Public awareness may be the

most significant. Many organizations are investing in this technology

with the hope that these products will be a common part of building

systems in the future. For now, only a few commercial and government

buildings utilize automated monitoring, and these few cases have shown

the concept to be viable. It is only a matter of time before automated

monitoring is installed as a common HVAC tool, and is expanded to

encompass other building systems.


Glossary

ABCAT Automated Building Commissioning and Analysis Tool

AEC Architectural Energy Corporation

AFDD Automated Fault Detection and Diagnostics

AHU/RTU Air Handler Unit/Roof Top Unit

APAR Air handling unit Performance Assessment Rules

ASHRAE American Society of Heating, Refrigeration andAir-conditioning Engineers

BAS Building Automation System

DABO Diagnostics Agent For Building Operators

FDD Fault Detection and Diagnostics

HVAC Heating Ventilating and Air Conditioning

IAQ Indoor Air Quality

LEED® Leadership in Energy and Environmental Design

NIST National Institute of Standards and Technology

O&M Operations and Maintenance

OSA Outside Air

OSAD Outside Air Damper

OAE Outside Air Economizer

PACRAT Performance and Continuous Re-commissioningAnalysis Tool

PECI Portland Energy Conservation Inc.

PNNL Pacific Northwest National Laboratory

USGBC United States Green Building Council

VAV (box) Variable Air Volume

VFD Variable Frequency Drive

WBD Whole Building Diagnostician


FOR MORE INFORMATION

ASHRAE (American Society of Heating, Refrigeration, and Air Conditioning

Engineers) established the APAR set in 2001. www.ashrae.org

Architectural Energy Corporation developed ENFORMA diagnostic software.

www.archenergy.com

CANMET Energy Technology Centre is Canada’s leading science and

technology organization with a mandate to develop and demonstrate energy-

efficient, alternative, and renewable energy technologies and processes.

www.nrcan.gc.ca

CTSB focuses on four major areas: research, advanced engineering, quality

assessment, and dissemination of knowledge. international.cstb.fr/default.asp

Efficiency Technologies, Inc. developed EffTrack. www.efftec.com

Energy Laboratory at Texas A&M University developed ABCAT.

esl.eslwin.tamu.edu/

Facility Dynamics created PACRAT. www.facilitydynamics.com

Field Diagnostics developed the Sentinel. www.fielddiagnostics.com

International Energy Agency Annex 40 Commissioning – HVAC

Commissioning of Buildings and HVAC Systems for Improved Comfort and

Energy Savings. The objective of Annex 40 was to develop, validate, and

document tools for commissioning of buildings and building services.

These tools include guidelines on commissioning procedures and

recommendations for improving commissioning processes, as well as

prototype software that could be implemented as stand-alone tools and/or

embedded in Building Energy Management Systems (BEMS). The work

performed in the Annex is focused on HVAC systems and their associated

control systems. www.commissioning-hvac.org/default.asp

NIST is the National Institute of Standards Technology, developer of APAR

and VPACC and co-developer of CITE-AHU. www.nist.gov

Pacific Northwest National Laboratory (PNNL), operated by Battelle for the U.S.

Department of Energy, is the developer of the Whole Building Diagnostician

and the Rooftop Diagnostician. PNNL’s mission is to provide basic and applied

research to deliver energy, environmental, and national security for the nation.

www.pnl.gov/

Tridium is the developer of the Niagara Framework®, a software framework

that integrates diverse systems and devices into a unified platform that can

be managed and controlled in real time over the Internet. www.tridium.com/


Notes

1. Brambley, Michael, and Srinivas Katipamula. “Beyond Commissioning.” The Role of Automation. Feb. 2005. Pacific Northwest National Laboratory.www.automatedbuildings.com/news/feb05/articles/pnl/pnl.htm

2. “Building Accountablity.” Cimetrics.www.cimetrics.com/home/infometrics/

3. Castro, Natascha S., and Hossien Vaezi-Nejad. CITE-AHU, an Automated Commissioning Tool for Air-Handling Units. National Conference on Building Commissioning, 2005.

4. Claridge, D.E. Engineering and Software Requirement of theAutomated Building Commissioning and Analysis Tool. Energy Systems Laboratory (ESL) at Texas A&M University. ESL, Texas A&M, 2005.txspace.tamu.edu/bitstream/1969.1/2081/1/ESL-TR-05-01-02.pdf

5. Intelligent Building Operating Technologies. CANMET EnergyCentre. Varennes: CANMET Energy Technology Centre, 2004.cetc-varennes.nrcan.gc.ca/fichier.php/codectec/En/2004-044/2004-044e.pdf

6. Mills, Evan. “Cost-Effectiveness of Commercial-BuildingCommissioning.” Dec. 2004. Lawrence Berkeley NationalLaboratory, Portland Energy Conservation, Energy SystemLaboratory. eetd.lbl.gov/emills/PUBS/Cx-Costs-Benefits.html

7. “PACRAT.” Facility Dynamics.www.facilitydynamics.com/Pacwho.pdf

8. Portland Energy Conservation, Inc. Methods for Automated andContinuous Commissioning of Building Systems. ARTI: 21-CR.Springfield: US Dept. Commerce, 2003.

9. Rauch, Christopher A. “Field Diagnostics Services, Inc.”Acrx.Com. 2002. www.acrx.com/FieldDiagnosticServicesIncCompanyDescription.pdf

10. Rooftop Diagnostician.availabletechnologies.pnl.gov/technology.asp?id=58

11. “Whole Building Diagnostician.” Building Systems Program. 20 Oct. 2005.www.buildingsystemsprogram.pnl.gov/fdd/wbd/index.stm

Energy Design Resources provides information and design tools toarchitects, engineers, lighting designers, and building owners anddevelopers. Our goal is to make it easier for designers to createenergy efficient new nonresidential buildings in California. EnergyDesign Resources is funded by California utility customers andadministered by Pacific Gas and Electric Company, SacramentoMunicipal Utility District, San Diego Gas and Electric, SouthernCalifornia Edison, and Southern California Gas Company, under theauspices of the California Public Utilities Commission. To learn moreabout Energy Design Resources, please visit our Web site atwww.energydesignresources.com.

This design brief was prepared for Energy Design Resources byArchitectural Energy Corporation.

09/2007

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