MEP Design Services Explained: Scope, Deliverables & Workflow

When an architect designs a building and a developer commits to construction, the success of that project depends enormously on the quality of MEP design services engaged to engineer the building’s systems. Yet many project owners and developers have limited visibility into what MEP design actually entails, what deliverables to expect at each phase, and how the workflow integrates with the broader design team.

This guide demystifies MEP design services from scope to workflow to deliverables. Budlong’s licensed engineers have designed MEP systems for hospitals, schools, commercial offices, government buildings, and industrial facilities throughout California. The following is an accurate and practical account of what professional MEP design services involve.

1. What Are MEP Design Services?

MEP design services are the professional engineering services required to design the mechanical, electrical, and plumbing systems of a building. These services are provided by licensed professional engineers (PE) and cover everything from initial system concept through the production of complete construction documents.

A comprehensive MEP design engagement transforms an architect’s floor plans and program requirements into a technically complete and code-compliant set of engineering drawings, specifications, and supporting calculations. The documents produced by MEP engineers are what contractors use to price, procure equipment for, and physically build the building’s systems.

Budlong’s MEP services cover all three disciplines — mechanical, electrical, and plumbing — with full internal coordination among discipline leads, ensuring consistent design intent and minimizing conflicts before construction begins.

2. Scope of MEP Design Services

The scope of MEP design services is defined by the project’s size, complexity, building type, and the owner’s specific requirements. While scope can vary, most full-service MEP design engagements include the following components across all three disciplines.

3. MEP Design Phases and Deliverables

MEP design services are delivered in phases aligned with the standard AIA project delivery framework. Each phase produces specific deliverables that build upon the work of the previous phase.

Phase 1: Predesign and Feasibility

During predesign, MEP engineers review the project program, conduct site utility investigations, evaluate existing systems (for renovation projects), and develop a preliminary Basis of Design. This phase may also include energy feasibility studies and assessment of sustainability certification requirements. Early engagement at this phase is strongly recommended — see our discussion of engaging HVAC engineers before architectural finalization.

Phase 2: Schematic Design (SD)

SD deliverables include a formally approved Basis of Design, schematic-level floor plans showing major equipment locations and primary system routing, preliminary equipment schedules, and a narrative description of each system. The SD package is used by the owner and architect to confirm design direction before committing to more detailed engineering work.

Phase 3: Design Development (DD)

DD documents develop the SD concepts into a more complete and spatially coordinated design. Deliverables include updated floor plans with more complete system routing, refined equipment schedules, single-line electrical diagrams, plumbing riser diagrams, and preliminary specifications. Clash coordination between MEP disciplines and with the structural system is also performed at this phase.

Phase 4: Construction Documents (CD)

Construction documents are the complete, permit-ready set of MEP drawings and specifications. They include fully detailed plan sheets for every level of the building, sections showing critical system routing and clearances, equipment schedules with final selections, technical specifications for each system, and all supporting calculations. MEP drafting services play a critical role in producing clear, accurate, and well-coordinated CD drawings.

Phase 5: Construction Administration (CA)

During construction, MEP engineers remain engaged to review and approve contractor submittals and shop drawings, respond to requests for information (RFIs), conduct periodic site visits to observe the installation, and support the commissioning process. Building commissioning services verify that installed systems meet design intent and perform as specified before the building is occupied.

4. Mechanical Design Scope in Detail

The mechanical discipline within MEP design services is responsible for HVAC systems that control temperature, humidity, ventilation, and air quality in the building. Mechanical design typically represents the largest share of MEP effort on most building types.

HVAC Load Calculations

Mechanical engineers perform heating and cooling load calculations using methods defined in ASHRAE Handbook — Fundamentals or California-specific tools for Title 24 compliance. These calculations determine the capacity of all HVAC equipment and are the foundation for equipment selection. HVAC design services at Budlong include full load calculations for every zone in the building.

System Selection and Equipment Design

Based on load calculations, the mechanical engineer selects the HVAC system type — which may be a split system, packaged rooftop unit, variable refrigerant flow (VRF) system, chilled water system, or dedicated outdoor air system (DOAS) — and specifies equipment to meet the calculated loads and efficiency requirements. Current HVAC design trends emphasize electrification, heat pump technology, and demand-controlled ventilation.

Ductwork and Hydronic System Design

Duct sizing, layout, and pressure drop calculations are performed to ensure adequate airflow to each zone. For hydronic systems, pipe sizing, pump selection, and system balancing are also within the mechanical design scope. Ductwork routing must be coordinated with the structural system, other MEP systems, and architectural ceiling heights.

5. Electrical Design Scope in Detail

The electrical discipline within MEP design services covers power distribution from the utility service entrance through every circuit and device in the building, as well as lighting design and low-voltage systems.

Electrical Load Calculations and Service Entrance

Electrical engineers calculate connected load, demand load, and short-circuit current to size the utility service, main distribution panel, and all downstream equipment. The electrical service entrance design must coordinate with the local utility company’s requirements and the building’s future load growth potential. Electrical design for future load expansion is a critical consideration that is often overlooked in cost-driven projects.

Power Distribution Design

Power distribution design includes the layout of switchgear, panelboards, transformers, and branch circuit wiring. For complex buildings, this also includes medium-voltage distribution, emergency power systems (generators and UPS), and automatic transfer switches. Electrical engineering for safety, reliability, and efficiency is central to Budlong’s electrical design practice.

Lighting Design

Interior and exterior lighting design encompasses fixture selection, layout, photometric analysis, and lighting controls. California Title 24 sets mandatory lighting power density limits, and MEP electrical engineers produce the compliance documentation required for permit. Architectural lighting design services from Budlong integrate both functional and aesthetic lighting objectives.

6. Plumbing Design Scope in Detail

Plumbing design within MEP services encompasses all water supply, drainage, and specialty piping systems in the building. Plumbing engineering services at Budlong cover domestic water, sanitary systems, storm drainage, gas piping, and medical gas systems for healthcare clients.

Domestic Water System Design

Plumbing engineers size the cold water distribution system and the domestic hot water (DHW) system based on fixture unit counts and system pressure requirements. Hot water system design must account for Legionella prevention through temperature maintenance and recirculation, which is particularly critical in healthcare and hospitality facilities.

Sanitary and Storm Drainage

Sanitary drainage systems are designed using fixture unit loading per the California Plumbing Code, with appropriate pipe sizing, slope, and cleanout locations. Storm drainage design accounts for roof drainage, area drains, and coordination with civil engineering for site drainage. Key principles of plumbing engineering guide Budlong’s approach to code-compliant drainage system design.

Specialty Plumbing Systems

Depending on building type, specialty plumbing scope may include medical gas systems, laboratory chemical waste systems, grease waste systems for food service, fire suppression piping, and process water systems for industrial or manufacturing clients. The importance of plumbing engineering in specialized facilities cannot be overstated.

7. MEP Coordination Workflow

The coordination workflow between MEP disciplines and with the broader project team is one of the most critical determinants of project success. Poorly coordinated MEP design is the single largest driver of construction rework and field change orders.

Internal MEP Discipline Coordination

Within the MEP team, coordination occurs continuously throughout design. Mechanical engineers need electrical power for equipment; plumbing engineers need access routes that avoid duct systems; electrical conduit banks need to be routed without blocking ductwork or pipe runs. Shared BIM models enable all three disciplines to design in the same coordinated space simultaneously.

Coordination with Architect and Structural Engineer

MEP engineers share updated models and drawings with the architect and structural engineer at defined coordination milestones. Penetrations through structural beams and slabs must be reviewed and approved by the structural engineer. Ceiling heights, shaft locations, and mechanical room dimensions must be coordinated with the architectural drawings. Integrated MEP services improve this coordination by providing a single point of contact for all three MEP disciplines.

BIM Clash Detection

Formal clash detection runs are conducted at DD and CD milestones using Navisworks or similar software. All hard clashes (physical intersections) and soft clashes (clearance violations) are documented in a clash matrix and resolved through discipline coordination meetings. BIM coordination advances have made this process faster and more reliable than ever.

8. How MEP Design Fees Are Structured

MEP design fees are structured in several ways depending on the nature and complexity of the project. Understanding the most common structures helps project owners budget accurately and evaluate proposals from competing firms.

Percentage of Construction Cost

For larger ground-up projects, MEP fees are often quoted as a percentage of the MEP construction cost (or total construction cost). Typical MEP design fees range from 3 to 8 percent of construction cost, with more complex building types (healthcare, laboratories) at the higher end of the range.

Lump-Sum Fixed Fee

For well-defined projects with clear scope, a fixed lump-sum fee provides cost certainty for both the owner and the engineer. This structure works well when the project’s scope, size, and program are established before the fee is negotiated.

Hourly Not-to-Exceed

For smaller projects, tenant improvements, or studies and assessments, an hourly not-to-exceed structure is common. The engineer tracks hours and bills monthly up to the agreed maximum. This structure is flexible but requires careful scope definition to avoid exceeding the budget.

9. Quality Control and Code Compliance

Quality control (QC) and code compliance are built into the MEP design process at Budlong through internal discipline reviews, peer reviews, and compliance check procedures before documents are issued for permitting or construction.

Internal QC Reviews

At each phase milestone, MEP documents are reviewed internally by a senior engineer who was not the primary designer. This review checks for technical accuracy, code compliance, coordination consistency, and completeness of specifications and details.

Title 24 and CALGreen Compliance

California projects require Title 24 energy compliance documentation produced by the MEP engineer. This includes HVAC system compliance forms (Mech-1, Mech-2, etc.) and lighting compliance forms (LTG-1, LTG-2, etc.). Sustainable design services from Budlong ensure that energy compliance is integrated into the design from the outset rather than retrofitted at the end of the CD phase.

Fire and Life Safety

MEP design services often include coordination with fire protection engineers for fire suppression and fire alarm systems. Fire safety engineering in MEP ensures that suppression systems, alarm panels, and MEP system interactions are properly designed and code-compliant.

10. Who Uses MEP Design Services?

MEP design services are engaged by a wide range of clients across California. Understanding which clients and sectors depend on professional MEP design helps frame the value of the service.

11. Related Reading

For further reading, consult the ASHRAE standards library, the U.S. Department of Energy Building Energy Codes Program, the Consulting-Specifying Engineer MEP resource center, NFPA codes and standards, and the IAPMO plumbing and mechanical codes.

12. Frequently Asked Questions