Article 96: Functional Performance Testing (FPT)

1. Introduction

Functional Performance Testing (FPT) represents the systematic process of validating that Building Automation System (BAS) components and integrated HVAC systems operate according to design specifications, sequence of operations, and owner requirements. This critical commissioning activity occurs after Pre-Functional Checklist (PFC) completion and verifies that all control strategies function correctly under actual operating conditions.

FPT serves as the definitive verification mechanism that confirms the "brains" of the building automation system—the DDC (Direct Digital Control) controllers, sensors, actuators, and software algorithms—perform their intended functions reliably. Unlike component-level testing, FPT evaluates system-level performance, inter-system coordination, and the complete signal path from sensing element through control logic to final controlled device.

ASHRAE Guideline 0 (The Commissioning Process) and ASHRAE Standard 202 (Building Commissioning) establish the foundational framework for FPT activities, while NEBB (National Environmental Balancing Bureau) Procedural Standards provide detailed methodologies for TAB (Testing, Adjusting, and Balancing) coordination with functional testing.

2. FPT Scope and Objectives

2.1 Scope Definition

The FPT scope encompasses all BAS-controlled equipment and systems, including but not limited to:

2.2 Primary Objectives

1. Verify Sequence of Operations: Confirm each control sequence executes correctly under all specified conditions
2. Validate Control Algorithms: Test PID loops, setpoint changes, staging logic, and optimization routines
3. Check System Integration: Ensure inter-system coordination (AHU-chiller, VAV-ahu, pump-plant)
4. Document Performance: Record actual versus expected performance for acceptance documentation
5. Identify Deficiencies: Discover and document system issues before owner acceptance

2.3 Testing Boundaries

FPT begins at the point where Pre-Functional Checklist items are complete: - All equipment is mechanically installed and electrically connected - All sensors are calibrated and verified - All DDC controllers are programmed and communication established - All actuators are installed and connected to controllers - Point-to-point verification is complete

3. Test Procedures for Air Handling Units (AHU)

3.1 Pre-Test Preparation

Before initiating AHU FPT, verify the following conditions:

3.2 Supply Fan Testing Sequence

Test ID: AHU-SF-01
Description: Supply Fan Modulation Control
Equipment: [AHU Designation]
Date: [Test Date]

Step 1: Verify fan status indication
         - Command fan ON from BAS
         - Confirm status point shows RUN
         - Record start-up current (compare to FLA)

Step 2: Test VFD modulation response
         - Setpoint: [Design CFM]
         - Current reading: _________ CFM
         - Expected: Within ±5% of setpoint
         - Result: PASS / FAIL

Step 3: Test duct static pressure control
         - Adjust setpoint to [Test Value] inHg
         - Measure response time: _________ seconds
         - Verify stable control (no oscillation >±10%)
         - Result: PASS / FAIL

Step 4: Test minimum speed setting
         - Command minimum ventilation
         - Verify speed ≥ [Minimum %] = _________%
         - Result: PASS / FAIL

3.3 Heating Coil Control Testing

3.4 Cooling Coil Control Testing

3.5 Mixed Air Plenum Testing

3.6 AHU Performance Acceptance Criteria

4. Test Procedures for Variable Air Volume (VAV) Systems

4.1 VAV Box Individual Testing

Each VAV terminal unit requires individual functional testing before system-level verification:

Series Fan-Powered VAV Testing

Test ID: VAV-FP-## (## = Box Number)
Box Type: Series Fan-Powered
Location: [Zone Designation]

Step 1: Verify box identification
         - Confirm BAS address matches physical location
         - Verify box size and type in software

Step 2: Test damper modulation
         - Command cooling maximum
         - Damper should open to 100%
         - Record: _________%

         Command cooling minimum
         - Damper should modulate to [Min CFM]%
         - Record: _________%

Step 3: Test reheat coil (if equipped)
         - Setpoint: [Room Temp + 5°F]
         - Reheat valve should modulate
         - Verify discharge air temperature rise

Step 4: Test series fan control
         - Fan should cycle based on thermal demand
         - Verify fan status indication
         - Test constant volume override

Parallel Fan-Powered VAV Testing

4.2 VAV System-Level Testing

After individual box testing, verify system coordination:

Static Pressure Control Verification

Zone Coordination Testing

4.3 VAV Performance Acceptance Criteria

5. Test Procedures for Chiller Plant

5.1 Pre-Test Requirements

5.2 Lead/Lag Chiller Sequencing

Test ID: CHP-LL-01
Description: Chiller Lead/Lag Rotation
Plant Configuration: [X] Chillers

Step 1: Verify lead chiller identification
         - Check BAS configuration
         - Confirm lead designation: Chiller #[X]
         - Verify lag identification: Chiller #[X], #[X]

Step 2: Test automatic rotation
         - Simulate lead chiller shutdown
         - Verify lag chiller starts within [X] seconds
         - Confirm automatic lead reassignment
         - Result: PASS / FAIL

Step 3: Test staged loading
         - Create load condition requiring 2 chillers
         - Verify second chiller starts at [X]% capacity
         - Verify equal runtime accumulation
         - Result: PASS / FAIL

Step 4: Test unequal loading
         - Verify optimized staging algorithm
         - Confirm most efficient combination
         - Result: PASS / FAIL

5.3 Condenser Water System Testing

5.4 Chiller Control Sequences

Chilled Water Reset Testing

Chiller Capacity Control

| Test Step | Action | Expected Response | Accept | |-----------||--------|-------------------|--------| | CCC-01 | Increase load command | Chiller steps up capacity | Smooth transition | | CCC-02 | Decrease load command | Chiller steps down capacity | Per manufacturer | | CCC-03 | Verify unloading sequence | Compressor stages OFF first | Per sequence | | CCC-04 | Test minimum capacity | Does not drop below [X]% | Manufacturer limit |

5.5 Chiller Plant Performance Criteria

6. Test Procedures for Pumps

6.1 Pump Pre-Test Verification

6.2 Variable Speed Pump Control Testing

Primary Chilled Water Pump Testing

Test ID: PUMP-PCH-##
Location: [Designation]

Step 1: Test constant speed operation
         - Set drive to 100%
         - Verify design flow rate: _________ GPM
         - Record motor current: _________ Amps
         - Result: PASS / FAIL

Step 2: Test VFD modulation - pressure sensor method
         - Set differential pressure setpoint: [X] psi
         - VFD should modulate to maintain pressure
         - Test at 25%, 50%, 75% load points
         - Verify no oscillation (hunting)
         - Result: PASS / FAIL

Step 3: Test speed limits
         - Command minimum speed
         - Verify ≥ [Min Speed]%: _________%
         - Verify safe minimum flow maintained
         - Result: PASS / FAIL

Step 4: Test pump staging
         - Simulate additional load
         - Verify second pump starts
         - Verify equal runtime sharing
         - Result: PASS / FAIL

6.3 Pump Control Sequence Tests

6.4 Pump Performance Acceptance Criteria

7. Data Logging Verification

7.1 Trend Log Configuration Review

Verify BAS trend log configurations capture all critical parameters:

7.2 Data Quality Verification

7.3 Alarm System Verification

8. Sequence of Operations Verification

8.1 Control Sequence Test Matrix

Verify each specified sequence of operations against design intent:

8.2 Critical Sequence Testing

Occupied/Unoccupied Transition

Test ID: SOO-OCC-01
Transition: Unoccupied → Occupied

Step 1: Verify unoccupied state
         - System in setback mode
         - Zone temps at setback values
         - Equipment at minimum

Step 2: Trigger occupied mode (scheduled or manual)
         - Morning warm-up/cool-down initiates
         - Equipment starts per startup sequence
         - Zone temperatures begin moving toward setpoint

Step 3: Verify transition timing
         - Occupied time: _________
         - Zones at setpoint time: _________
         - Transition duration: _________ minutes
         - Result: PASS / FAIL (≤60 min target)

Step 4: Verify system stabilization
         - All zones within ±1°F of setpoint
         - No simultaneous heating/cooling
         - Equipment at optimal staging

8.3 Integration Sequence Testing

9. Seasonal Testing

9.1 Seasonal Testing Requirements

ASHRAE Guideline 0 requires seasonal testing to verify system performance under actual load conditions:

9.2 Summer Seasonal Testing

9.3 Winter Seasonal Testing

9.4 Seasonal Testing Report Requirements

Each seasonal test report shall include: - Test dates and duration - Weather conditions during testing - System operating mode and setpoints - Performance data (temperatures, flows, pressures) - Deviations from design conditions - Corrective actions taken - Recommendation for seasonal acceptance

10. Documentation Requirements

10.1 Required FPT Documentation

10.2 FPT Report Content

The Functional Performance Testing Summary Report shall include:

1. Executive Summary
2. Project overview
3. FPT scope and methodology
4. Overall test results summary

5. Outstanding deficiencies

6. Test Results by System

7. Each tested system
8. Test procedures performed
9. Actual vs. expected results

10. Pass/fail status

11. Deficiency Summary

12. List of all deficiencies
13. Severity classification
14. Resolution status

15. Verification documentation

16. Performance Verification

17. Trend data analysis
18. Energy performance comparison

19. Comfort assessment

20. Recommendations

21. Optimization opportunities
22. Maintenance recommendations
23. Training needs

10.3 Record Retention

11. Common Failures and Resolutions

11.1 Control System Failures

11.2 Equipment Integration Failures

11.3 Performance Failures

11.4 Documentation Failures

12. Frequently Asked Questions (FAQ)

Q1: What is the difference between Pre-Functional Testing and Functional Performance Testing?

A: Pre-Functional Testing (PFT) verifies individual component installation and readiness—this includes confirming sensors are calibrated, actuators are connected, and controllers are communicating. Functional Performance Testing (FPT) goes beyond to verify that systems perform their intended functions under actual operating conditions, testing complete sequences of operation, system integration, and dynamic performance. PFT is prerequisite to FPT; FPT cannot begin until PFT is complete.

Q2: When should FPT be scheduled relative to construction completion?

A: FPT should be scheduled during the commissioning process after Pre-Functional Checklists are substantially complete (typically 80-90%+), but before owner acceptance. Best practice schedules FPT to allow time for deficiency correction before seasonal testing. For occupied buildings, FPT may need to occur during off-hours to minimize disruption while still testing under realistic conditions.

Q3: What is the minimum staffing for FPT?

A: Effective FPT requires at minimum two qualified persons: one to operate the BAS and monitor responses, and one at equipment locations to observe physical responses and take field measurements. Additional personnel may be needed for complex systems or large buildings. All personnel should understand the sequences of operations and testing procedures.

Q4: How long does FPT typically take for a commercial building?

A: FPT duration varies significantly based on building size, system complexity, and the number of systems. A typical 100,000 sq ft commercial building may require 2-4 weeks of testing. Larger or more complex facilities (hospitals, data centers) may require 6-8 weeks or more. The testing should not be rushed; adequate time must be allowed to test all sequences under various conditions.

Q5: Can FPT be performed on existing buildings?

A: Yes, FPT principles can be applied to existing buildings through retrocommissioning. The process is similar but adapted: existing systems must be evaluated, sequences must be documented through investigation, and testing focuses on verifying current operation meets design intent and owner requirements. ASHRAE Standard 100 provides guidance for existing building commissioning.

Q6: What are acceptance criteria for FPT?

A: Acceptance criteria should be defined in the Owner's Project Requirements (OPR) document and include: - Equipment performance (temperatures, flows, pressures within specified ranges) - Control response times (systems respond within specified timeframes) - Energy performance (systems operate within expected energy budgets) - Indoor environmental quality (temperatures, humidity within comfort ranges) - Safety systems (all interlocks and safety devices function correctly)

Q7: How should deficiencies be documented?

A: Deficiencies should be documented in a deficiency log that includes: - Unique identifier number - Date and time discovered - Location and system affected - Description of the deficiency - Expected vs. actual performance - Severity (critical, major, minor) - Responsible party - Resolution date and verification - Supporting documentation (photos, trend data, etc.)

Q8: What is seasonal testing and why is it required?

A: Seasonal testing verifies system performance under actual peak load conditions—summer cooling/dehumidification and winter heating/humidification. Systems must be tested under real conditions because: - Design conditions rarely occur during initial testing - Full load performance differs from partial load - Controls may behave differently under actual weather conditions - Energy performance should be verified seasonally

ASHRAE Guideline 0 requires seasonal testing as part of complete commissioning.

Q9: How does FPT relate to ASHRAE 90.1 compliance?

A: ASHRAE 90.1 Section 6.7.5 requires functional testing of HVAC controls as part of mandatory commissioning. The testing must verify: - Control sequences operate as specified - Equipment is controlled to optimize energy performance - Setpoint reset controls function correctly - Deadband and staging controls function - Interface between building automation and equipment

FPT provides the documentation required to demonstrate 90.1 compliance.

Q10: What training is required before FPT?

A: Operations and maintenance (O&M) staff should receive training before FPT completion to ensure they can: - Navigate the BAS interface - Respond to alarms - Make setpoint adjustments - Interpret trend data - Perform routine maintenance - Document system changes

Training should be documented with sign-off sheets and completion certificates.