Using Computational Fluid Dynamics to Optimize HVAC Design

Leverage the power of simulation on your next building design

High demands are placed on modern HVAC systems to create optimal indoor environments while minimizing energy usage. Consequently, usage of computer-based analysis tools like computational fluid dynamics (CFD) that aid in the design of these systems is becoming more prevalent. With the recent addendum to ASHRAE 62.1 we expect the demand for CFD analyses to increase even further. The change states that a CFD analysis can be used to estimate the ventilation effectiveness value used to determine the outdoor air requirement instead of tables provided in the standard.

We understand that a CFD analysis doesn’t make sense for every project, but this article is aimed at helping you determine the types of projects that can benefit from conducting a CFD analysis.

As it relates to building design, CFD is best suited to difficult to design spaces within a building. It is also recommended for spaces that repeat many times throughout a building like an office (private or open) or a patient room. Generally, projects that are well suited for a CFD analysis fall into two categories: high-risk environments and challenging applications.

A  High-risk Environment is defined as a controlled environment that requires precision control of temperature, humidity, and/or air quality in the space. Examples of these spaces include clean rooms, labs, drug storage facilities, agriculture and horticultural facilities, health care facilities, specialized manufacturing and archival vaults.

When thinking about whether your project would classify as a high-risk environment that would benefit from a CFD analysis, ask yourself the following questions.

• Does this space require a high accuracy in control systems?
• Does this space require stable and reliable conditions?
• Would a failure in the system have a high economic impact on the owner?

CFD results for a hospital surgical room application.

Images on the left show temperature and velocity at 66 in. above the floor.

The other types of applications that are well suited to CFD are Challenging Applications. Challenging applications might use an engineered product such as chilled beams or displacement ventilation, or a conventional system that is applied in a large open space. Other spaces that fall into this category include applications that are subject to extreme heat gains or losses. Examples include atriums, auditoriums, battery storage facilities, airport terminals, areas with high ceilings or no ceiling, and areas with a large glass façade.

Questions to consider with these projects include:

• Are there any best practices for this type of design?
• Does the engineer have experience designing this type of application, or using this HVAC technology?
• Would a miscalculation in the design result in costly rework?
• Is a physical mock-up possible?

CFD results showing ventilation effectiveness of an auditorium using displacement ventilation.

With over 10 years of experience in modelling indoor environments, the Predict team can model any indoor space. Predict works directly with the Price engineering teams to ensure all of the product design details and performance information is built into the model.

To learn more about Predict, or if you come across a project you believe is well suited for a CFD analysis, we encourage you to contact us at CFD@priceindustries.com.