4-Pipe VAV vs. Active Chilled Beams for Labs

Steve Taylor, Taylor Engineering

Variable air volume (VAV) laboratory HVAC systems, including VAV fume hoods, are now standard practice and dramatically improve energy efficiency compared to the constant volume systems they replaced. To further improve efficiency, modern laboratory HVAC designs focus on two primary goals: minimizing the energy used to condition outdoor air and minimizing terminal unit reheat energy. In this regard, several guides and articles encourage using active chilled beams (ACB) in lab zones. But ACBs are often not the best choice from a cost and efficiency perspective. This presentation discusses an alternative design, 4-pipe VAV (4PVAV) systems, which is often cheaper and more efficient. The presentation will discuss the details of what makes a lab ventilation-dominated, hood-dominated or load-dominated and how these categories help define when ACB or 4-pipe VAV systems can save more energy.

Learning Objectives

  • Explore the pros and cons of using active chilled beams versus 4-pipe VAV systems;
  • become familiar with different lab types as they define which system type is more appropriate;
  • understand the difference between a load-dominated, hood-dominated, and ventilation-dominated lab space; and
  • understand the cost and energy implications of two popular mechanical systems used in laboratories.


Steve Taylor is a Principal at Taylor Engineering in Alameda, California. He graduated from Stanford University with a BS in Physics and a MS in Mechanical Engineering and has 40 years of commercial HVAC and control system design and construction experience. He is a Fellow of the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) and one of very few to have received all of ASHRAE's top awards for technical achievement.


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