Design Process Phases
The HVAC design process progresses through defined phases, each building upon the previous to develop complete construction documents. Understanding phase deliverables and coordination requirements ensures efficient project execution and quality outcomes.
Phase Overview
Traditional Design Phases
| Phase | Effort | Key Deliverables |
|---|---|---|
| Programming | 5-10% | Requirements document |
| Schematic Design | 15-20% | System concepts, single-lines |
| Design Development | 25-30% | Equipment sizing, layouts |
| Construction Documents | 35-40% | Complete bid documents |
| Construction Administration | 10-15% | Submittals, field support |
Phase Progression
Each phase refines design detail:
Programming → SD → DD → CD → CA
[Concepts] → [Systems] → [Equipment] → [Details] → [Installation]
Programming Phase
Objective
Define project requirements and constraints before design begins.
Activities
- Facility assessment (existing conditions)
- Owner interview (operational requirements)
- Code review (applicable standards)
- Budget establishment
- Schedule development
HVAC Deliverables
- Preliminary load estimates
- System type recommendations
- Utility capacity assessment
- Phasing considerations
- Special requirements identification
Schematic Design (SD)
Objective
Establish overall HVAC system concepts and approaches.
Activities
- Conceptual load calculations
- System selection
- Equipment location concepts
- Preliminary ductwork/piping routing
- Controls approach
- Energy analysis (preliminary)
HVAC Deliverables
| Document | Content |
|---|---|
| SD Report | System narratives, basis of design |
| Floor Plans | Equipment locations, major routing |
| System Diagrams | Single-line flow diagrams |
| Equipment List | Preliminary sizing |
| Code Summary | Applicable standards |
Coordination
- Architectural space allocation
- Structural load coordination
- Electrical power requirements
- Site utility connections
SD Review
Owner approval milestone:
- System concept acceptance
- Budget alignment
- Schedule confirmation
- Authority to proceed to DD
Design Development (DD)
Objective
Develop selected systems with specific equipment and layouts.
Activities
- Detailed load calculations
- Equipment selection
- Ductwork/piping sizing
- Control sequences
- Coordination drawings
- Energy modeling
- Life cycle cost analysis
HVAC Deliverables
| Document | Content |
|---|---|
| DD Drawings | Scaled floor plans, sections |
| Equipment Schedules | Sized equipment data |
| Control Diagrams | System schematics |
| Specifications | Outline specs |
| Energy Report | Code compliance, analysis |
DD Drawing Set
Mechanical Plans:
- Equipment layouts
- Ductwork routing and sizing
- Piping routing
- Device locations
Details:
- Typical installations
- Equipment connections
- Coordination sections
Schedules:
- Equipment data
- Diffuser schedules
- Control valve schedules
Coordination Intensive
- Clash detection (BIM coordination)
- Ceiling coordination
- Shaft sizing verification
- Equipment access planning
Construction Documents (CD)
Objective
Complete documents suitable for competitive bidding and construction.
Activities
- Final sizing verification
- Complete detailing
- Specification completion
- Coordination resolution
- Permit submissions
- Quality control review
HVAC Deliverables
Drawings:
- Complete floor plans
- Enlarged plans (mechanical rooms)
- Sections and elevations
- Details (all required)
- Schedules (complete)
- Diagrams (control, riser)
Specifications:
- Division 23 complete
- Product specifications
- Execution requirements
- Quality assurance provisions
Quality Control
- Internal technical review
- Coordination verification
- Code compliance check
- Constructability review
- Cost estimate validation
CD Milestones
Typical submission stages:
- 50% CD: Major systems complete
- 90% CD: Near-complete for review
- 100% CD: Bid-ready documents
- Permit Set: Authority submissions
Construction Administration
Objective
Support construction to ensure design intent is achieved.
Activities
- Submittal review
- RFI response
- Field observation
- Change order support
- Commissioning coordination
- Closeout documentation
Deliverables
- Reviewed submittals
- RFI responses
- Field reports
- Punch lists
- Record drawing support
Phase Integration
BIM Coordination
Model development by phase:
- SD: Conceptual massing
- DD: System routing, major equipment
- CD: Detailed components, clash-free
Cost Control
Estimate refinement:
- Programming: Order of magnitude (±30%)
- SD: Conceptual (±20%)
- DD: Detailed (±10%)
- CD: Contractor pricing (±5%)
Schedule Management
Track design schedule:
- Phase completion dates
- Review period duration
- Coordination milestones
- Permit timeline
Understanding design phase progression enables appropriate effort allocation, timely deliverables, and successful project outcomes through systematic development of HVAC systems from concept to construction documents.
Sections
Proposal Phase
HVAC design proposal development including project understanding, scope definition, fee calculation methods, qualifications statements, team organization, schedule development, and proposal presentation strategies for mechanical engineering services
Schematic Design Phase
Comprehensive guide to HVAC schematic design phase including system concept development, preliminary load calculations, equipment space allocation, major equipment selection, energy analysis, and schematic drawings for HVAC professionals
Design Development Phase
Comprehensive guide to HVAC design development phase including detailed system design, equipment selection finalization, duct and pipe sizing, control sequences, interdisciplinary coordination, cost estimating, and DD drawings and specifications for mechanical engineering projects