How Can HVAC Systems Ensure Better Indoor Air Quality (IAQ)?

Optimizing HVAC equipment with smart building automation systems (BAS) equipped with AI can significantly enhance indoor air quality (IAQ), both for new and retrofit building applications. Plus, it can also boost ROI in the form of workplace productivity, which can be as much $800 per employee, per year in the United States. Facility teams focused on IAQ understand the importance of increasing clean, filtrated airflow within the building. Conditions are constantly shifting in response to weather, outdoor air quality, occupant behaviors and equipment health – all of which can pose a challenge when it comes to optimizing occupant health, wellness, and productivity. Combining HVAC equipment like air handling units (AHUs) and dedicated outdoor air systems (DOAS) with intelligent BAS solutions enables both HVAC equipment and IAQ performance to be continuously monitored and enhanced in real-time. Using AI and machine learning algorithms, the BAS can adjust HVAC equipment and building systems autonomously to maintain optimal performance as conditions change. These smart platforms not only enhance HVAC performance, but they also provide operators with data that is easy to interpret while being presented with action steps. This information can help them make decisions about equipment upgrades, space utilization and maintenance strategies while staying aligned to their IAQ goals.

Most individuals think of HVAC systems as simply providing heating or cooling for a building. While that is true, the operation of the HVAC system is also essential to indoor air quality (IAQ). A central HVAC system distributes air through ductwork and can influence IAQ in several ways:

• Filtration: Removing pollutants, dust, and allergens from the air.
• Ventilation: Introducing fresh outdoor air to dilute CO₂, VOCs, and other contaminants.
• Temperature and Humidity Control: Maintaining comfortable conditions and preventing mold or mildew growth.

The integration of radiant heating and cooling can further enhance IAQ. Radiant systems reduce the amount of air that needs to be circulated, lowering the spread of dust and allergens. By pairing radiant with an ERV/HRV (residential) or DOAS (commercial), the system can dedicate air movement to filtration, fresh air supply, and humidity control, ensuring a healthier indoor environment.

Indoor air quality (IAQ) is becoming a top priority in commercial buildings, yet as an industry, we are still developing a clear baseline for what “good” IAQ really looks like. We are now recognizing that construction phases and system upgrades can have a significant, and often overlooked, impact on pollutant levels—particularly spikes in volatile organic compounds (VOCs) that were previously underestimated. HVAC systems are central to meeting these challenges. High-efficiency filtration is essential, with ASHRAE recommending MERV 13 or higher filters to capture fine particulates, allergens, and even airborne viruses. Just as important is proper system installation and ongoing maintenance to ensure reliable performance. Ventilation strategies have evolved beyond fixed schedules. With CO₂ sensors, demand-controlled ventilation, and longer operating hours, HVAC systems can deliver outdoor air exactly when and where it is needed. This targeted approach helps dilute indoor pollutants while avoiding unnecessary energy use. The CDC’s recommendation of at least five air changes per hour highlights the need for adaptive, real-time airflow management. Today, smart HVAC technologies make this possible. With IoT sensors, live air quality monitoring, and intelligent controls, we can now adjust ventilation dynamically in response to changing conditions—whether those are driven by occupants, materials, or outdoor air. This enables better IAQ while maintaining a balanced, energy-efficient strategy.

Buildings today face rising expectations for comfort, efficiency and indoor air quality, and HVAC systems sit at the center of it all. For many facilities, the path forward starts with optimizing what already exists. Retrofitting hydronic systems, for instance, allow building owners to improve air quality, comfort, and performance without the cost or disruption of a full replacement. Hydronic systems are water-based systems, which are a more efficient medium for heat transfer than air. Hydronic technology improves indoor air quality by separating air distribution from temperature control, reducing the spread of harmful airborne particles while maintaining consistent comfort. Despite these benefits towards efficiency and air quality, there are still ways legacy systems can be improved through retrofit. Legacy systems driven by constant speed motors with flow throttled by valves often take longer periods of time to stabilize temperature, operate less quietly, and are subject to more severe temperature swings in response to sharp changes in demand. Hydronic systems powered by variable frequency drives and high-efficiency motors enable quieter, more precise, control of temperature and system output, helping maintain stable conditions in different areas throughout the building at a lower cost. Used in conjunction with connected controls and sensors, another layer of intelligence is added that allows facility teams to monitor performance continuously, detect inefficiencies early, and make targeted adjustments that extend equipment life. Employing these upgrades with energy-efficient equipment, building owners can create spaces that support occupant health today while positioning their systems for greater resilience and performance in the future.

Maintaining true indoor air quality starts with recognizing that no amount of filtration can replace outdoor air—filters can capture particles, but they can’t address CO₂, formaldehyde, or the broader mix of gas-phase contaminants that accumulate in occupied spaces. The challenge, of course, is conditioning that outdoor air efficiently, which is where liquid-desiccant systems change the equation. By delivering extremely efficient latent removal and biocidal air treatment at the DOAS level, liquid desiccant makes ventilation far less energy-intensive and reduces the need for complex control strategies just to keep humidity in check. And maintaining humidity control is critical: excess moisture drives mold and bacterial growth on surfaces where filtration offers no protection. By pairing robust outdoor-air ventilation with high-efficiency liquid-desiccant treatment, buildings can achieve healthier air, simpler operations, and more resilient IAQ performance in all conditions.