Wildfires and Indoor Air Quality: Engineering Strategies for Commercial HVAC and Educational Facilities

Wildfires continue to intensify due to climate change, posing significant challenges to indoor air quality (IAQ) in commercial buildings and schools. As wildfire smoke contains high levels of fine particulate matter (PM2.5) and gaseous pollutants, engineers face the complex task of minimizing infiltration through HVAC systems while keeping energy efficiency and system performance intact.

Increased wildfires has created more focus on the impact smoke has on HVAC systems

The Engineering Challenge: Wildfire Smoke Infiltration

Wildfire smoke can infiltrate buildings through several pathways:

• Natural Ventilation and Air Infiltration: Open windows, doors, and even small cracks in the building envelope can allow outdoor air, laden with PM2.5, to compromise indoor environments.

• Mechanical Ventilation: HVAC systems designed to bring in fresh air may unwittingly draw in particulate pollutants unless properly adjusted during smoke events.

  
  

For engineers focused on commercial HVAC and air quality, the challenge is to design or retrofit systems that not only cater to occupant comfort but also provide robust barriers against smoke intrusion. This requires careful evaluation of air handling units, ductwork sealing, and the selection of air filters that strike a balance between high efficiency and acceptable pressure drop.

Optimizing HVAC Performance with Enhanced Filtration

One of the most effective strategies for protecting IAQ during wildfire events is upgrading the air filtration system. Key technical considerations include:

• High-Efficiency Filters: Engineers should consider using filters with a MERV 13 rating or higher. These filters capture much of the PM2.5 while still allowing sufficient airflow. However, it’s essential to assess the HVAC system’s fan capacity and ductwork to avoid increased static pressure that can decrease efficiency.

• Supplemental Filtration Options: Deploying portable air cleaners and supplemental filtration at air intakes can significantly reduce indoor particulate levels during peak smoke periods. These units, designed for commercial settings, can be integrated into existing maintenance plans and monitored through digital control systems.

• Smart Sensor Integration: Incorporating low-cost or calibrated air sensors into the building management system (BMS) allows real-time monitoring of indoor PM2.5 concentrations. Data from these sensors can be used to dynamically adjust ventilation rates and filtration settings, ensuring a balance between fresh air intake and the minimization of outdoor pollutants.

  
  

Adapting HVAC Operations During Smoke Events

Beyond hardware upgrades, operational modifications are vital when defending indoor air quality:

• Adjusting Ventilation Settings: During periods of heavy smoke, engineers can optimize HVAC settings by reducing the intake of outside air and increasing the recirculation of indoor air through high-efficiency filters. This not only protects the interior environment but can also reduce energy consumption by lessening the load on the cooling system.

• Developing a Smoke Readiness Plan: A comprehensive plan tailored to each building should include pre-event maintenance checks, stockpiling spare filters, and protocols for rapid deployment of portable air cleaners. Factoring in weatherization measures to reduce envelope leakage is equally critical in both commercial buildings and schools.

  
  

Implementing and Testing Engineering Solutions

When retrofitting or designing systems for enhanced IAQ:

• System Compatibility and Testing: Engineers must verify that new filtration and sensor components are compatible with legacy HVAC systems. This often requires bench testing and on-site validation to ensure that system adjustments do not inadvertently compromise indoor climate control.

• Collaboration with ASHRAE Guidelines: Guidance documents such as ASHRAE Guideline 44 help bridge the gap between current HVAC design practices and the emerging needs dictated by wildfire smoke challenges. These guidelines offer a framework for evaluating filter performance, assessing air handling unit (AHU) readiness, and determining the optimum operational regimes during smoke events.

• Maintenance and Monitoring Protocols: Regular maintenance, including periodic pressure drop measurements across filters and verification of sensor calibrations, is essential. A proactive approach ensures that commercial HVAC systems continue to operate at peak efficiency while delivering high-quality indoor air.

  
  

Building Resilient Commercial and Educational Environments

The increasing prevalence of wildfires calls for engineers to be on the forefront of adapting commercial HVAC systems—and by extension, schools and public buildings—to protect indoor air quality. By integrating high-efficiency filtration, leveraging real-time air quality sensors, and adopting dynamic operational strategies, engineering teams can significantly reduce indoor smoke levels and ensure the health and productivity of building occupants.

How is your team preparing your commercial HVAC systems or school facilities for wildfire smoke events? Have you identified key integration points for high-efficiency filters or advanced air sensors that can serve as critical components in your smoke readiness plan?

Exploring innovative filtration technology, enhancing building envelope sealing, and continuous monitoring are just a few ways the engineering community is responding to this pressing air quality challenge. As these strategies evolve, they will shape the future of sustainable and resilient building design in a wildfire-prone environment.