Lesson 2 – Design Intent and Owner’s Project Requirements (OPR)
Lesson Objective
In this lesson, you will understand why HVAC designs fail when project intent is not clearly defined.
You will also learn what the Owner’s Project Requirements (OPR) are and how they guide design decisions.
What Is Design Intent?
Dsign intent is a clear statement of what the owner wants to achieve from the building.
It describes goals, not solutions. It answers the question: “What does success look like for this project?”
In HVAC projects, design intent may include goals such as:
- Thermal comfort
- Energy efficiency
- Low operating cost
- Simple maintenance
- High system flexibility
Without a clear intent, every design decision becomes subjective.
From Intent to Measurable Criteria
Design intent alone is not enough.
Each intent must be supported by clear and measurable criteria. These criteria define the minimum acceptable performance.
This is where the Owner’s Project Requirements (OPR) come in.
For example:
- Intent: Provide good thermal comfort
- Criterion: Comply with ASHRAE thermal comfort requirements
- Intent: Achieve energy efficiency
- Criterion: Meet energy code limits or specific efficiency targets
The OPR connects intent to design decisions.
What Is the Owner’s Project Requirements (OPR)?
The OPR is a documented summary of the owner’s expectations and requirements.
It defines:
- Indoor environmental conditions
- Operating schedules
- Energy and efficiency targets
- Maintenance expectations
- Special system requirements
The OPR provides the reference against which all design decisions are evaluated.
Example 1 – Comfort Without Definition
An owner asks for “high comfort” in an office building.
No temperature range is defined.
No humidity limits are specified.
No noise criteria are mentioned.
After occupancy, occupants complain:
- Some areas feel too cold
- Others feel too warm
- Noise complaints increase
The HVAC system may be working correctly, but expectations were never defined.
Example 2 – Comfort Defined Through OPR
Aanother project, comfort is clearly defined in the OPR:
- Indoor temperature range is specified
- Humidity limits are defined
- Noise criteria are stated
Design decisions become easier:
- System selection is clearer
- Zoning strategy is justified
- Control strategies are aligned with expectations
The result is fewer disputes and better performance.
Why OPR Is Critical for HVAC Designers
HVAC designers rely on the OPR to justify their decisions.
When questions arise about:
- System selection
- Equipment size
- Control complexity
- Budget trade-offs
The OPR becomes the reference point.
Without it, the designer is forced to defend decisions based on personal opinion.
Example 3 – Energy Efficiency vs First Cost
In HVAC designer proposes a high-efficiency system.
The owner rejects it due to higher first cost.
If the OPR prioritizes low capital cost, the rejection is valid.
If the OPR prioritizes long-term energy savings, the rejection contradicts the project intent.
The OPR prevents confusion and misalignment.
Key Takeaway
Design intent defines goals.
The OPR translates those goals into measurable requirements.
Without a clear OPR, HVAC design becomes reactive and defensive instead of deliberate and controlled.
Reflection Question
In your recent projects, was the design intent clearly documented — or did it exist only as verbal expectations?