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Did you know that Americans spend approximately 90% of their lives in indoor environments? The U.S. Environmental Protection Agency first shared this finding back in 1994 with the National Human Activity Pattern Survey and since then, the figure has inched upwards. A more recent study published in 2024 in the Journal of the American Planning Association shows that Americans now spend nearly an hour less outside their homes daily compared to 2019, indicating a lasting trend toward indoor living.
Indoor air quality (IAQ) is a critical factor in maintaining health, safety, and operational efficiency in any built environment. In hospitals, for example, clean air is essential for patient recovery and staff well-being, as poor IAQ can worsen respiratory conditions and increase infection risks. Airports, with their high foot traffic and enclosed spaces, depend on good air quality to reduce the spread of airborne illnesses. Commercial office buildings and university campuses observe an impact on occupant health as well as productivity when air quality is compromised, often leading to absenteeism and decreased performance.
Beyond health concerns, IAQ is tied to regulatory compliance, as many jurisdictions enforce standards such as ASHRAE and OSHA to ensure occupant safety and avoid costly penalties. Monitoring and managing IAQ supports operational efficiency via HVAC optimization, which in turn reduces energy consumption and maintains comfort.
Modern sensor-based solutions make it possible to track pollutants in real time. Identifying impurities like CO₂, PM2.5, VOCs (volatile organic compounds), humidity, temperature, and radon helps facility teams pinpoint poorly ventilated areas and analyze trends. These insights allow predictive maintenance, allowing for HVAC adjustments, and enhance occupant experience. When issues arise, organizations deploy mitigation strategies like increasing ventilation, upgrading filtration systems, controlling pollutant sources, managing occupancy patterns, and scheduling maintenance such as duct cleaning and filter replacement. Ultimately, proactive IAQ management safeguards health and improves operational efficiency and sustainability.
Willow offers three key sets of skills that support these mitigation strategies. Let’s walk through each of these.
Willow insights related to valve position play an important role in maintaining and improving air quality in buildings. Here’s how:
1. Control outdoor air flow and recirculation rates: Insights on valve position ensure that outdoor air dampers and water or steam coil control valves are modulating appropriately based on actual occupancy or demand. This is crucial for maintaining recommended ventilation rates and keeping pollutant levels, such as CO₂ low. Examples of Willow Skills that call out adjustment of outdoor air valve and damper position are: AHU Outside Air Damper(s) Tuning, AHU Not Using Dry-Bulb Economizer and AHU is Not Operating While Outside Air Damper Open.
2. Demand-Controlled Ventilation (DCV) Optimization: Insights may leverage sensors such as CO₂ and humidity to drive ventilation valves to modulate fresh air intake precisely as needed. This prevents excess buildup of CO₂ and other contaminants while enabling energy-efficient operation. A Willow Skill that addresses DCV is Outside Air Intake Above Minimum while Return Air CO₂ is Below Setpoint.
3. Automated feedback prompts corrective action: Willow insights compare commanded valve position, i.e. what the building automation system tells the valve to do, with actual valve position measured by feedback sensors. If a valve is stuck, hunting, or misadjusted, insights quickly flag the issue so it can be corrected, hence preventing under- or over-ventilation which can negatively affect air quality. Examples of Willow skills for valve and damper fault detection include AHU Cooling Command (Output) != Position Feedback (Input), Terminal Unit Damper Command (Output) != State Feedback (Input), and Terminal Unit Damper Position Constant While Zone Temperature is not at Setpoint.
4. Pre-emptive issue detection and occupant comfort: By providing timely insights and recommendations tied to valve position discrepancies, Willow enables operators to maintain compliance with ASHRAE indoor air quality standards and keep spaces comfortable for occupants. Examples of Willow skills for occupant comfort and compliance include Multiple Terminal Units Served by AHU have Dampers that are Fully Open and VAV Airflow is Below Airflow Setpoint with Damper at 100%.
Willow has skills that specifically pertain to filter replacement and maintenance in HVAC systems. These skills provide actionable insights for timely filter changes, which directly impacts air quality and system efficiency. A skill called AHU Dirty Filter – Switch indicates that the Air Handling Unit’s filter alarm switch has activated. This means that the filter sensor has detected a dirty or clogged filter. This is a direct signal that filter replacement or maintenance is required. Similarly, AHU Dirty Filter – Differential Pressure is triggered when the differential pressure across the unit’s filters exceeds a set threshold, indicating clogging, restricted airflow, or dirty filters requiring cleaning or replacement.
Willow skills and insights, when integrated with IAQ sensors, provide automated, data-driven actions to maintain and improve the building’s indoor air quality. Here’s how this process works:
First, IAQ sensors continuously measure parameters such as CO₂, VOCs, particulate matter (PM2.5/PM10), humidity, temperature, and even radon. This sensor data is fed into the Willow platform as real-time or near-real-time telemetry. Then, Willow skills monitor the incoming sensor values. Skills come prebuilt or can also be further configured to assess when IAQ levels are outside of recommended thresholds, e.g. CO₂ above 1,000 ppm, VOCs elevated, or PM2.5 exceeding 35 μg/m³. When a parameter exceeds its designated safe range, Willow generates an insight. For example, if CO₂ from a sensor trends above threshold, the skill Space CO₂ Level High or IAQ Sensor CO₂ Alert will trigger an actionable insight in the platform.
Each insight contains recommendations. Examples include: increase outdoor air ventilation, check and replace HVAC filters, inspect operation of zone-level dampers and review building occupancy or special source of pollutants. These recommendations are tailored to address the source of poor IAQ identified by the sensor. Insights can trigger automated ticket generation and maintenance workflows, ensuring a documented response. When BMS integration is also deployed, Willow’s Active Control can automatically adjust HVAC setpoints, damper positions, or ventilation schedules in response to the sensor reading.
As an example, when CO₂ levels exceeds threshold, the skill Space CO₂ Level High is triggered with a recommended action for the facilities team to increase ventilation or adjust the outdoor airflow setpoint. To monitor for PM2.5 levels, the Particulate Level Above Safe Limit skill generates a recommended action to check the filtration system and investigate the source of the particulates. VOC is monitored with a skill called VOC Alert Detected. The insight recommends boosting ventilation and to identify and remove potential sources like cleaning agents. If humidity readings from the sensors indicate out of range conditions, a skill for High/Low Humidity Warning enables adjustment of humidification or dehumidification as needed. Facility teams may be advised to inspect ventilation and the building envelope.
Another example is Space Air Quality Above ASHRAE Recommendation. This skill detects when the air quality within a space exceeds the recommended limits set by ASHRAE standards. It monitors sensor data such as particulate matter, CO₂, or other air quality indicators relative to ASHRAE threshold values. When levels surpass these recommendations, the skill generates an insight alerting operators to potential issues with ventilation, filtration, or occupancy that may affect comfort and safety within the space.
Running these skills constantly with Willow ensures that there is continuous and automated oversight with no lapse in monitoring. The insights provide a targeted set of context-specific steps for the facilities team. This minimizes trial-and-error and ensures faster IAQ correction. Last but not least, an audit trail is generated. Each IAQ event and mitigation step can be tracked, supporting compliance and occupant safety.
Willow skills transform IAQ management with strategies that simplify real time VAV air flow adjustment, condition based filter replacement and reading raw IAQ data from sensors into immediate, actionable insights. This helps organizations create environments where people can truly breathe easy every day.