VC-21A-C051 – How to Design a Variable Air Volume Central Hospital Air Handling System

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Hospital air systems require a significant effort in design. Each space must be assessed for minimum outdoor air ventilation, minimum total ventilation, and pressure relationship. These considerations complicate the design process for a central air handling system. This paper is an offshoot of California Energy Commissioning research project “Advanced HVAC Technology Demonstration Project to Reduce Natural Gas Use in Hospitals”, where existing constant-volume systems were converted to variable air volume. During the project, the design process for variable volume systems had to be articulated. Once articulated for the project, we formulated it into a generic design process, which is presented here.

The following is a process for design of variable volume central air handling systems in US hospitals. It includes seven steps, (1) define the peak and neutral conditions, (2) divide the space into zones, (3) load calculations (peak condition), (4) peak condition room balance schedule (RBS), (5) neutral condition room balance schedule (RBS), (6) operating performance prediction and (7) acceptance criteria for commissioning.

Step five, in particular is novel, since it involves the design engineer calculating air flows and room balances at a system minimum condition. Most design engineers are quite familiar with calculations at the maximum heating and maximum cooling conditions. But, creating an explicit design for the neutral or system minimum condition may be a new practice to many. Steps 6 and 7, which are optional, are needed for operational performance validation, when data systems are used in commissioning to validate the design intent, i.e. if a data-based, monitoring based, or connected commissioning system is used.

Product Details

Published:
2021
Number of Pages:
9
Units of Measure:
Dual
File Size:
1 file , 2.7 MB
Product Code(s):
D-VC-21A-C051
Note:
This product is unavailable in Russia, Belarus