The owner’s project requirements (OPR) is the owner’s plain-language statement of what the building must do; the basis of design (BOD) is the design team’s technical explanation of how the system will meet it. Together they anchor a commercial HVAC project — the OPR defines success, the BOD documents the engineering choices, and commissioning later verifies the building delivers both.
The owner’s project requirements document what the owner needs in their own terms: temperature and humidity expectations, occupancy and hours, energy goals, budget, redundancy needs, maintenance capacity, and any operational quirks. It is intentionally non-technical — it is the owner’s voice, not the engineer’s.
A clear OPR is the reference point that keeps a project honest. When a value-engineering decision comes up later, the OPR is what you check it against.
The basis of design is the technical answer to the OPR. It records the design conditions used, the load assumptions, the system type selected and why, equipment efficiencies, ventilation strategy, control approach, and the codes and standards followed.
The BOD is where the engineering reasoning lives. If someone asks two years later why the building has a chilled-water plant instead of VRF, the BOD has the answer.
The OPR is requirements; the BOD is response. The OPR says “the data room must stay below 75°F continuously, even during a utility outage.” The BOD says “a dedicated split system with N+1 redundancy on standby power, sized for X tons.”
Without the OPR, there is nothing to measure the design against. Without the BOD, there is no record of the engineering logic. Commissioning needs both to do its job.
Functional performance testing during commissioning verifies that the installed system meets the BOD, and that the BOD actually satisfies the OPR. The documents are the test script. A building cannot be meaningfully commissioned without them — there is no standard to test against.
This is why thorough owners and good design-builders insist on writing both early, not reconstructing them at closeout.
In design-build, the OPR is developed jointly with the owner at the start, and the design-builder authors the BOD as the design develops — keeping both under one accountable roof. On owner’s-rep engagements, we help the owner write the OPR and then hold the design team’s BOD to it.
Either way, these documents are cheap to produce and expensive to omit. They are the foundation the design-build process is built on.
The owner’s project requirements (OPR) is the owner’s plain-language statement of what the building must do. The basis of design (BOD) is the design team’s technical explanation of how the system meets those requirements. The OPR defines success; the BOD documents the engineering response.
The OPR is the benchmark every later decision is measured against — system selection, value engineering, and commissioning all reference it. Without it, there is no agreed definition of what the building is supposed to achieve.
The design team — in design-build, that is the design-builder. It records design conditions, load assumptions, system selection rationale, equipment efficiencies, ventilation and control strategy, and the codes followed.
Commissioning verifies that the installed system meets the basis of design and that the design satisfies the owner’s project requirements. The OPR and BOD are the standard the functional performance testing is run against.
Suncoast Cold Systems delivers commercial HVAC design-build across Tampa, St. Petersburg, Clearwater, Brandon, Riverview, Temple Terrace, and Wesley Chapel — load calcs, equipment selection, layouts, controls, install, and commissioning under one contract. Licensed Class A A/C Contractor (FL #CAC1824642), with a Florida PE of record on sealed work.
Where the OPR and BOD fit in the six phases.
How the building is verified against the BOD.
Working under your seal and design intent.