Project Delivery Method: Design-Build (D-B)

Owner Team: Hospital president, owner representative (consultant), project manager of capital projects, and facility manager (in-house staff)

Project Delivery Team: D-B project manager and HVAC D-B engineer

HVAC Project Team: HVAC supervisor (in-house staff); automatic temperature control (ATC) technician subcontractor; building automation system (BAS) technician (in-house staff); third-party commissioning consultant (CxC); third-party testing, adjusting, and balancing (TAB) technician; and infection control consultant (IC)

Application 2019 ASHRAE Handbook: Healthcare Facilities, Chapter 9

Systems 2020 ASHRAE Handbook: Air Cleaners for Particulate Contaminants, Chapter 29

Project Type: Infrastructure improvements

References: 2017 ASHRAE Handbook – Fundamentals; refer to the codes and standards section in the back of each ASHRAE Handbook for additional reference; ASHRAE Standard 170 (Ventilation of Healthcare Facilities); ASHRAE Standard 202 (Commissioning Process for Buildings & Systems); and the Design-Build Institute of America (DBIA)


  • The HVAC system selection and design intent are based on the process outlined in ASHRAE Handbook 2020, Chapter 1, “HVAC System Analysis and Selection,” and include the following:
    • Owner’s building program goals and additional goals 
    • System constraints and constructability constraints
    • Finalized air filter MERV rating and unit sizes
    • The ATC shall include new automatic controls, a BACnet interface, and internet interface to the existing BAS interface and existing computerized maintenance management software (CMMS) system interface
  • Program and Project Goals:
    • Functional goals: (refer to 2020 Handbook, Chapter 1)
    • Budget goals: first cost, operating cost, and life cycle cost
    • Timeline goals: phased construction date throughout the hospital 
    • Management goals: air filtration and IAQ management 
  • Existing Conditions: 
    • Central air systems
    • Minimum, air-side economizer and 100% outside air systems 
  • Central Air Systems:
    • Supply air systems: single-duct, single-zone, single-duct-multiple zones with terminal units, dual-duct dual-fan, rooftop, underfloor air distribution (UFAD), primary-secondary, constant volume, and variable air volume (VAV) 
    • Pre-filter, final filter, after filter, HEPA filter, and fan-power HEPA filter unit with a MERV rating based on the area served
  • Supply Air Fans:
    • Add variable frequency drive (VFD) to reengineered existing central air systems with filter differential pressure drop control set points 


  • The HVAC design criteria shall be in sync with:
    • D-B project delivery method 
    • The owner’s project requirements 
    • The design criteria shall be based on an analytical analysis of existing HVAC conditions, associated operation, and proactive maintenance management in sync with the hospital’s overall needs, updating the policy and procedure manual as it pertains to occupant comfort and IAQ and infection control. 
    • From this updating of the P&P manual, the existing central air-handling systems will be rebalanced and retro-commissioned after enhanced filter MERV-rated filters replace existing filters.
  • The design criteria shall be based on:
    • ASHRAE Standard 170, “Ventilation of Healthcare Facilities”
    • ASHRAE Standard 202, “Commissioning Process for Buildings & Systems”
    • Retrofit all central air systems with a new VFD
  • Conceptual/schematic phase general notes:
    • The D-B HVAC design engineer shall provide system flow diagrams with each HVAC system along with the ATC sequences of operation 
    • The facility manager shall have the O&M technicians trained to accommodate P&P changes as they affect the HVAC system occupant comfort, IAQ, etc. 

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