Engineering Effective Ventilation Systems for Industrial Facilities

Why Moving Beyond Minimum Standards Is Essential for Worker Safety

Industrial facilities with fuel-fired vehicles face one of the toughest indoor air quality challenges in the industry. Constant vehicle movement makes traditional exhaust capture systems impractical, leaving these environments vulnerable to harmful contaminants like carbon monoxide (CO), nitrogen dioxide (NO₂), and diesel particulate matter (DPM). Many of these pollutants are toxic, and several are recognized carcinogens by global health organizations.

At SMS Engineering, we’ve seen firsthand how relying solely on prescriptive code requirements can leave workers under‑protected in these high‑risk spaces. Today’s exposure limits are more stringent than ever, and effective solutions must be engineering engineered around real operating conditions, not generic design assumptions.

In this article, we break down the modern strategies and engineering tools that help us design ventilation systems that aren’t just compliant, they’re genuinely protective.

Why Ventilation Matters More Than Ever

Exhaust fumes aren’t just unpleasant, they’re dangerous. In facilities where vehicles idle or operate indoors, contaminants can accumulate rapidly without proper ventilation, increasing the risk of both short‑term respiratory irritation and long‑term chronic health effects.

Regulatory bodies have tightened exposure limits in response to growing evidence of harm. A key example is the American Conference of Governmental Industrial Hygienists (ACGIH) reducing the Threshold Limit Value – Time Weighted Average (TLV‑TWA) for NO₂ from 3 ppm to 0.2 ppm. With limits this stringent, meeting standards requires engineering precision, not outdated prescriptive rates.

Prescriptive vs. Performance-Based Ventilation Design

Traditional design standards, such as ASHRAE 62.1 and the ACGIH Industrial Ventilation Handbook, provide prescriptive airflow rates (e.g., 1.5 cfm/ft² for service bays or 10,000 cfm per propane‑fueled lift truck). While these values offer a baseline, they often fail to capture the complexity and variability of actual industrial operations.

A performance-based approach changes the game. offers a more accurate and protective solution. Rather than relying on fixed numbers, it focuses on actual contaminant concentrations in workers’ breathing zones. This requires facility‑specific assessments, advanced modelling, and a deeper analysis of how a space is truly used.

Understanding the Air You Can’t See

Advanced simulation tools allow engineers to visualize how contaminants like CO, NO₂, and DPM move through a facility under different operating scenarios.

Gas diffusion and particulate modelling consider:

• Traffic flow and movement patterns

• Idle durations and warm‑up cycles

• Ventilation layout and supply/exhaust locations

• Worker positioning and exposure points

  
  

This data enables engineers to:

• Determine ventilation rates based on actual contaminant loads

• Design targeted and efficient air distribution strategies

• Ensure exposure limits are consistently met, not just averaged

  
  

Modelling transforms invisible risks into actionable design guidance.

Smarter Dilution Ventilation

In facilities with frequent vehicle movement, dilution ventilation, introducing clean outdoor air to mix with and dilute contaminants, is often the only feasible strategy. When direct tailpipe extraction isn’t practical, dilution becomes essential.

However, not all dilution systems are equally effective.

A significant improvement is delivering fresh air directly at the worker’s breathing zone, rather than introducing it overhead. This increases ventilation effectiveness dramatically and reduces the overall airflow (and energy) required.

Additionally, in areas where vehicles idle in predictable locations, localized exhaust hoods can be added to create a hybrid solution that boosts contaminant removal without disrupting operations.

Air Distribution That Works Harder

Air distribution is one of the most important elements of an effective ventilation system. Thoughtful airflow design ensures contaminants are carried away from workers rather than recirculated throughout the space.

One of the most efficient configurations is a low‑level supply combined with high‑level exhaust, which promotes upward movement of warm, contaminated air and reduces short‑circuiting in the space. 

To support this, engineers may use:

• Floor‑mounted supply plenums to deliver clean air directly where workers need it

• Zoned ventilation controls to manage high‑activity or high‑risk areas independently

• Right‑sized equipment that meets performance targets without unnecessary energy use

  
  

This approach not only improves contaminant removal but also enhances energy efficiency and overall system performance.

Winter Operations: Why Cold Weather Raises the Stakes

Cold weather introduces new challenges that can significantly impact indoor air quality. In winter, bay doors stay closed longer, vehicles idle more during warm‑up cycles, and natural air infiltration decreases. These factors all contribute to higher contaminant buildup.

Winter also increases thermal stratification, warm, contaminated air rises and becomes trapped above the workspace, making ceiling‑level diffusers far less effective than they are in milder seasons.

Designing for winter means:

• Reinforcing low‑level air supply to break up stagnant layers and ensure contaminants are captured effectively

• Adjusting airflow rates and control sequences to reflect seasonal operational demands

• Integrating make‑up air tempering so cold outdoor air can be introduced without sacrificing worker comfort or energy performance.

  
  

Winter operations aren’t just a colder version of normal operations, they fundamentally change how air moves in a facility. Ventilation systems must be designed to perform reliably in both the mildest and harshest conditions.

Key Takeaways for Smarter Ventilation Design

✔ Go Beyond the Code Requirements

Prescriptive standards don’t always align with modern exposure research. Performance‑based design ensures workers are truly protected.

✔ Use Hybrid Strategies When Possible

Combining dilution ventilation with localized exhaust capture maximizes effectiveness.

✔ Optimize for Efficiency

Better airflow patterns reduce energy use, right‑size equipment, and boost overall system performance.

The Bottom Line

Effective ventilation isn’t just about compliance, it’s about protecting the people who work in these facilities every day. In industrial environments, especially those with constant vehicle movement, that means adopting performance‑based design and engineering solutions tailored to real operational conditions.

At SMS Engineering, we design intelligent, responsive, and data‑driven ventilation systems that create safer, healthier workplaces, grounded in engineering precision and proven through real‑world results.