What is the primary purpose of a Basis of Design (BOD) document in HVAC projects?

• A. It documents design decisions, control philosophy, sequences, and instrumentation choices.
• B. It lists the project schedule and milestones.
• C. It provides the equipment procurement cost estimates.
• D. It sets the building's energy codes.

Answer: (A)

The Basis of Design captures the decisions that define how the HVAC system should operate, including the control philosophy, sequences of operation, and the instrumentation choices. This document serves as the single reference for designers, contractors, and commissioning agents to understand the intended behavior of the system, ensuring the owner's requirements are met and that all design work stays aligned with that intent. It guides equipment selection, performance criteria, and the overall design approach, and it helps verify that changes remain consistent with the established direction. Schedules, milestones, and cost estimates belong to project management and budgeting, while energy-code compliance is addressed in separate code-based documents; the BOD may reference relevant codes but its primary purpose is to articulate design intent and how the system should function.