Ongoing commissioning and preventive maintenance are complementary but distinct activities with different focuses, methodologies, and objectives, both essential for optimal building performance.
Preventive Maintenance (PM) focuses on equipment preservation through regular physical maintenance activities: filter changes, belt replacements, lubrication, cleaning, component inspections, and scheduled part replacements. PM prevents equipment failures, extends equipment life, and maintains warranty coverage. In-house or outsourced maintenance technicians perform PM following manufacturer schedules and specifications, typically documented in Computerized Maintenance Management Systems (CMMS).
PM asks: “Is equipment physically sound and likely to operate reliably?”
Ongoing Commissioning focuses on verifying systems perform as designed through functional testing, sensor calibration, control sequence verification, and integrated system performance assessment. Commissioning confirms equipment operates correctly, controls respond properly to varying conditions, systems integrate effectively, and performance meets design intent.
Commissioning asks: “Is equipment operating correctly to meet performance requirements efficiently?”
Key differences:
• Scope: PM addresses individual equipment; commissioning addresses integrated system performance.
• Methods: PM involves physical inspection and component replacement; commissioning uses functional testing and performance measurement.
• Frequency: PM typically occurs monthly or quarterly per equipment schedules; commissioning occurs quarterly to annually per building needs.
• Expertise: PM requires maintenance technician skills; commissioning requires system-level engineering expertise.
• Focus: PM is proactive (preventing breakdowns); commissioning is proactive and can often be predictive with historical data review and/or MBCx capabilities (optimizing performance).
Example scenarios illustrating the difference:
A cooling tower receives PM: cleaning basins, treating water, replacing worn fill, lubricating fan motors, and inspecting belts. Commissioning verifies: tower achieves design approach temperature, staging control sequences operate correctly, lockouts function properly, and tower integrates with chiller plant optimization strategies.
An air handling unit receives PM: filter changes, belt tension adjustment, bearing lubrication, coil cleaning. Commissioning verifies: supply air temperature controls properly, economizer operates correctly, minimum outside air meets ventilation requirements, heating and cooling don’t operate simultaneously, and static pressure resets appropriately.
Integration for maximum effectiveness: PM keeps equipment operating; commissioning ensures equipment operates correctly toward intended outcomes. Equipment with excellent PM but no commissioning often runs reliably while operating incorrectly, wasting energy while providing inadequate performance. Equipment with commissioning but inadequate PM may operate correctly briefly before failing.
Optimal facility management includes both PM and ongoing commissioning, maintenance preserves equipment, commissioning optimizes performance.
For ongoing commissioning programs complementing your preventive maintenance to achieve comprehensive building system management, contact Catalyst Commissioning Group at info@catalystcx.com.