Commissioning drawing review
What commissioning agents look for during design and construction document review.
Why Commissioning Reviews Drawings
Commissioning is the systematic process of ensuring building systems perform as intended. The commissioning agent (CxA) reviews drawings at multiple design stages to catch issues that would otherwise surface only during functional testing, when fixes are expensive and schedule-critical. A good CxA review at DD or 60% CD prevents the most common categories of late-stage rework.
Review Milestones
- Owner's Project Requirements (OPR) review, confirms design intent is documented before drawings exist
- Basis of Design (BOD) review, confirms designer's response to OPR
- Schematic Design (SD) review, verifies system selection aligns with OPR
- Design Development (DD) review, verifies sizing, zoning, and controls strategies
- 60% / 95% Construction Documents review, detail-level coordination, sequence of operations, and testability
- Submittal review, verifies submitted equipment matches design and OPR
What to Look for in Mechanical Drawings
- Equipment schedules match the BOD and OPR sizing
- System zoning aligns with intended occupancy and use patterns
- Outdoor air calculations meet ASHRAE 62.1 and any project enhancement targets
- Sequence of operations included for every system, not just summarized
- Control sensor locations specified and accessible for verification
- Test ports, balancing dampers, and measurement stations shown
- Equipment access for maintenance and testing reachable per code
- Heat recovery, economizer, and DCV controls clearly specified
- Hydronic system arrangement supports proper balancing
What to Look for in Electrical Drawings
- Panel schedules show actual loads and demand factors
- Emergency and standby power transfer schemes clear and testable
- Lighting controls include daylight, occupancy, and time-of-day per IECC
- Sub-metering points specified per OPR or jurisdiction requirements
- Power quality measurement (where required) accessible for monitoring
- Equipment locations match mechanical drawings (no orphan power feeds)
What to Look for in Plumbing and Fire Protection
- Domestic hot water recirculation balanced and metered
- Backflow preventers accessible for annual testing
- Fire pump test header location and discharge path documented
- Sprinkler hydraulic calculations match the system delivered
- Standpipe test connection accessible
Sequence of Operations: Don't Skip
The single biggest source of late-stage commissioning rework is missing or vague sequences of operations. A good CxA review confirms that every controlled system has a written sequence that covers occupied mode, unoccupied mode, warm-up, cool-down, alarms, safeties, and failure modes. If the sequence is described only as "system shall maintain comfort conditions," that's a flag.
Run the proposed sequence on paper against a realistic day's operation. If you can't trace what every controlled device does in response to every sensor input, the sequence isn't buildable, let alone testable.
Documents Required for Functional Testing
- Final approved sequence of operations
- Submittal data for installed equipment
- Approved Test & Balance report
- Control system points list and graphics
- Updated drawings reflecting field changes
- Manufacturer startup reports
- Equipment trend data covering minimum required test period
Keep exploring
Related references and guides for commissioning and design review.
Understanding mechanical, electrical, and plumbing systems.
Catch code issues before plan review.
Best practices for coordinated drawing review.
HVAC schedules, diffusers, and sequences of operation.