NOTE
You’re Already Designing (You Just Don’t Know It)
In the course of our work, energy engineers regularly assess existing building systems and make recommendations for improvements—whether it’s upgrading HVAC equipment for better efficiency, retrofitting lighting systems, or optimizing controls for energy savings. However, many energy engineers may not realize that when they develop these recommendations, they are inherently engaging in the engineering design process.
Whether suggesting a boiler replacement, proposing a new air handler configuration, or recommending electrical system upgrades, energy engineers are essentially working through design phases—often without the formal structure or terminology used by traditional MEP design firms and the wider AEC industry.
As an energy engineer making technology recommendations, you are performing some level of design work regardless of whether you work at a traditional design firm. Your recommendations don’t exist in isolation; they must integrate with the broader building systems and follow the same progression from concept to implementation
The AEC industry breaks design work into distinct phases, each with specific goals, deliverables, and levels of detail. Understanding these phases helps energy engineers know what to expect and what to ask for at each stage of a project.
Each phase builds upon the previous one, with increasing levels of detail and precision. The SD phase establishes “what” systems will be used, the DD phase determines “where” and “how big,” and the CD phase specifies “exactly how” everything will be installed. This progression allows for design refinement while managing project costs and schedules effectively.
Pre-Design / Programming
This is the phase before formal design begins. The project team identifies needs, establishes goals, develops preliminary budgets, and defines the scope. Energy efficiency goals and utility program requirements should be established here.
Schematic Design (SD)
The Schematic Design phase marks the beginning of the MEP engineering process, where broad concepts are translated into preliminary system strategies. During this phase, engineers work closely with architects and other design team members to establish the fundamental framework for building systems. The completion of the SD phase is usually considered around 25%-30% design completion. Cost estimates at this phase are rough.
Key Objectives in the SD phase:
- Preliminary System Selection: Engineers determine the most appropriate HVAC, electrical, and plumbing systems based on building type, occupancy, and project goals
- Load Analysis: Preliminary calculations for heating/cooling loads, electrical demand, and plumbing fixture requirements
- Space Planning: Coordination with architects to allocate space for major equipment (mechanical rooms, electrical rooms, elevators)
- Sustainability Goals: Integration of energy efficiency strategies and renewable energy considerations
Typical SD phase deliverables:
- Single-line diagrams showing primary system configurations
- Equipment schedules with approximate sizes and capacities
- Basic floor plans indicating equipment locations and major distribution routes
- Preliminary energy models and utility consumption estimates
- Initial cost estimates and system comparisons
During SD, engineers focus on proving the viability of their system concepts rather than detailed design. The drawings are intentionally simple, often showing equipment as blocks or symbols without specific routing of pipes, ducts, or conduits.
Design Development (DD)
The Design Development phase represents a significant step forward in detail and coordination. Engineers refine their schematic concepts into more defined systems that can be properly coordinated with architectural and structural elements. The design becomes more specific. Systems are sized, materials are selected, and major components are defined. Drawings show more detail but aren’t yet at the level needed for construction. The completion of the DD phase is usually considered around 50%-60% design completion. Cost estimates become more refined.
Key Objectives in the DD phase:
- System Refinement: Detailed system selection with specific equipment types and performance criteria
- Load Calculations: More precise engineering calculations with actual equipment selections
- Spatial Coordination: Three-dimensional coordination with structure, architecture, and other trades
- Code Compliance: Detailed code analysis and compliance verification
- Performance Optimization: Fine-tuning systems for efficiency, maintainability, and constructability
Typical DD phase deliverables:
- Detailed floor plans showing equipment, major ductwork, piping, and conduit routing
- Riser diagrams illustrating vertical distribution systems
- Equipment schedules with specific manufacturers and model numbers
- Preliminary control sequences and system operation descriptions
- Updated energy models with refined equipment selections
- Detailed cost estimates with better accuracy
In the DD phase, the “big picture” systems are broken down into their component parts. Engineers must now consider how air handlers connect to ductwork, how electrical panels feed specific loads, and how plumbing systems handle both supply and waste. This phase requires extensive coordination meetings to resolve conflicts between trades.
Construction Documents (CD)
The Construction Documents phase produces the final, bid-ready drawings and specifications that contractors will use for pricing and construction (in a traditional design-bid-build delivery method). Every detail necessary for proper installation must be documented clearly and completely. The design is considered 100% complete.
Key Objectives in the CD phase:
- Complete Documentation: Every pipe, duct, conduit, and piece of equipment fully detailed and dimensioned
- Technical Specifications: Comprehensive written specifications covering materials, installation methods, and performance requirements
- Constructability Review: Analysis of installation sequences and access requirements
- Quality Standards: Clear definition of testing, commissioning, and acceptance criteria
- Final Coordination: Resolution of all conflicts between trades and building systems
Typical CD phase deliverables:
- Fully detailed floor plans, sections, and details showing every system component
- Complete equipment schedules with cut sheets and installation requirements
- Comprehensive control diagrams and sequences of operation
- Written technical specifications for all materials and equipment
- Details and sections showing critical installation conditions
- Complete electrical panel schedules and circuit listings
- Plumbing fixture schedules and utility service requirements
Bidding / Procurement
Not always considered a distinct design phase, but contractors review the construction documents and submit bids. The design team may answer questions and issue clarifications.
Warning
For Energy Engineers: When you ask for a “design” or “cost estimate,” which phase are you really asking about? A schematic-level estimate will be very different from a construction document-level estimate. Similarly, trying to finalize energy savings calculations during schematic design often means making assumptions that will change as the design develops.
As-Built Drawings
UCSD Definitions
From: https://plandesignbuild.ucsd.edu/design/descriptions.html
Pre-Design
A project charter is developed which defines the preliminary and conceptual scope, budget and schedule of the project. The charter indicates the needs and functions of the user and the potential square footage. Following selection of an Executive Design Professional, potential pre-design includes preparation of a Detailed Project Program.
Schematic Design
Schematic design is the first phase of basic services for project design. At this stage in a project, the design professional describes the project three-dimensionally. A range of alternative design concepts are explored to define the character of the completed project and an optimum realization of the detailed project program.
Design Development
During the design development phase, the project design is further refined. Plan arrangements, specific space accommodations, equipment and furnishings, building design, materials and colors, and complete definitions of all systems serving the project are developed. All design decisions are completed during this phase in order to prepare the subsequent construction documents.
Construction Documents
The construction document phase consists of preparation of drawings and specifications establishing the requirements for construction of the project. The construction documents describe the quality, configuration, size, and relationship of all components to be incorporated into the project. Construction documents must be consistent with the detailed project program, the construction budget and the project schedule. The construction documents serve as a basis for obtaining bids from contractors and are used by contractors to obtain price quotes from subcontractors.