Project Delivery Method: Design-bid-build (DBB)
Owner Team: Pharmaceutical building manager, owner representative consultant, facility manager (in-house staff), and third-party commissioning (Cx) agent
Project Delivery Team: HVAC consulting firm’s project manager and design engineer; electrical, plumbing, and structural engineer consultants; and the utility company representative
HVAC Project Delivery Team: The HVAC contractor was awarded the project based on the contract document bid as well as the “best value” in lieu of the lowest bid. Other team members include the DBB HVAC job superintendent, supervisor, automatic temperature control (ATC) subcontractor, and the rigging subcontractor
2019 ASHRAE Handbook HVAC Application: Commercial & Public Buildings, Chapter 3; and Industrial Air-Conditioning, Chapter 15
2020 ASHRAE Handbook HVAC Systems and Equipment: Condenser Water Systems, Chapter 14; and Cooling Towers, Chapter 40
Project Type: Infrastructure (central process cooling and HVAC chilled water system cooling) and facility differed maintenance master plan implementation
References: 2019 ASHRAE Handbook, HVAC Applications; and 2020 ASHRAE Handbook, HVAC Systems and Equipment
Other References: Cooling Technology Institute (cooling towers); ASHRAE Guideline 22, Instrumentation for Monitoring Central Chilled Water Plant Efficiency; ASHRAE Fundamentals of Design and Control of Central Chilled-Water Plants; ASHRAE Standard 202, Commissioning Process for Buildings and Systems; and Facility Condition Index (FCI) – a standard facility condition benchmark
DESIGN INTENT DOCUMENT (DID)
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 included FCI financial evaluation by the company’s asset master plan to repair rather than replace the two 800-ton cooling towers serving the pharmaceutical company’s condenser water system. The existing towers were in poor operating condition, unreliable, and expensive to operate.
A DBB firm, which also serves as the pharmaceutical facility’s mechanical service company contractor, was chosen as the best value prime contractor for the job.
Existing equipment to remain as part of the condenser water system includes the plate and frame heat exchangers and split-case pumps with standby pumps, each with variable frequency drives (VFDs). Automatic controls shall include new controls, a BACnet interface, and an internet interface with an existing building automation system (BAS) interface.
The infrastructure program and project goals shall include energy performance goals and budget goals, i.e., first cost, operating cost, life cycle cost, and return on investment (ROI). The timeline shall be completed during heating season.
The management goals include reduced energy consumption and improved reliability.
The pharmaceutical owner’s team shall contract the services of an owner representative to facilitate the DBB process from conceptual design intent documents through the one-year warranty phase.
The owner representative shall contract the services of a third-party commissioning agent to assist in the overseeing of the DBB contract and compliance with the design team’s contract documents.
DESIGN CRITERIA DOCUMENT
• The HVAC design criteria shall be in sync with the project delivery method. The equipment retrofit replacement is based on contract drawings and specifications, including division 1 general conditions and supplementary general conditions.
• The design criteria shall be based on an existing ATC sequence of operation for the pharmaceutical’s process chilled water system that operates year-round and the HVAC chilled water system during the air conditioning season.
• The new cooling towers shall each be capable of operating year-round and be furnished with electric sump pan heaters and pump head pressure control on heating season VFD process cooling. During air conditioning season, the two new towers, each sized for two-thirds of the total cooling capacity shall operate in parallel with the associated VFD chilled water and condenser water pumping systems.
• Condenser water pipe distribution shall be insulated and include electrical heat tracing on the winter outdoor pipe distribution.
• The existing plate and frame heat exchanger shall function on waterside economizer mode operation with one new cooling tower with the plate and frame heat exchanger separating process chilled water from condenser water system, while the HVAC chilled water system and associated pumps shall be off during the heating season.
• Based on the infrastructure and management project goals, the condenser water and chilled water systems shall have flow meters and Btuh energy metering furnished and installed per ASHRAE Guideline 22, Instrumentation for Monitoring Central Chilled Water Plant Efficiency.
• The addition of a new BAS computer system with remote monitoring and management shall be interfaced with the existing process chilled water system and HVAC chilled water system to reduce operating cost and enhance operation and maintenance year-round.
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