Open vs. Closed Processes: Choosing the Right Approach for Manufacturing Facilities

One of the most important decisions in designing a manufacturing space, especially in a science and technology environment, is how much to expose the product during production. The choice between an open or closed process directly influences cleanroom classification, airflow strategy, operating costs, and long-term flexibility.

WHAT IS AN OPEN PROCESS?

An open process includes any manufacturing step that exposes the product to the surrounding environment, even for a second. These steps may involve manual handling, operations in biosafety cabinets, or open workstations. Because the product is exposed, the room itself must provide protection. Typically, this means higher cleanroom grades, increased air changes, and stronger HVAC systems. Open processes usually occur during the earlier stages of manufacturing or when product enclosure isn’t feasible.

WHAT IS A CLOSED PROCESS?

A closed process keeps products fully contained within equipment. Since the product is isolated, the surrounding room’s systems are less necessary in controlling contamination.

Closed processes reduce risk while allowing lower cleanroom classifications and flexibility for more energy-efficient HVAC strategies. As manufacturing scales, we favor closed systems for consistency, safety, and operational efficiency.

HOW DO THESE AFFECT FACILITY DESIGN

Open processes require larger air–handling systems, more filtration, and higher operating costs. Closed processes require more advanced equipment upfront, but allow for smaller, uncomplicated facilities.

Air strategy is the big differentiator. Open viral processes require 100% once-through air, while closed systems allow air recirculation, which reduces energy use.

WHEN IS EACH APPROACH APPROPRIATE?

Open processes are best when flexibility and hands-on handling are needed or when the process is still developing. Closed processes are the better option when using established manufacturing processes, materials are expensive, and when long-term efficiency is imperative.

Most facilities employ a hybrid approach, closing as many steps as possible while designing the environment to support the remaining steps.

THE TAKEAWAY

Open and closed processes are not opposing strategies. Understanding when to use each allows teams to build manufacturing spaces that are efficient and scalable as needs change.

Have a question about your science and technology manufacturing space? Connect with me at rdoyle@wbengineering.com.