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Indoor Air Quality and HVAC Systems: How IAQ Monitoring Optimizes HVAC System Performance

People spend over 90% of their days inside of buildings, and we have HVAC systems to thank for the comfortable experience. HVAC systems, a key component of modern buildings, are responsible for controlling crucial aspects of building occupant comfort, like temperature, humidity, and air quality. 

hvac ductwork

With growing interests in sustainability and green building, people are looking to reduce the amount of energy consumed by their HVAC systems while preserving its core purpose: creating a comfortable, healthy indoor environment. How can this be achieved? One strategy is air quality monitoring. 

First, we are going to briefly introduce what HVAC stands for, as well as link to some resources for you to learn more about HVAC. 

HVAC overview

The term ‘HVAC’ stands for heating, ventilating, and air conditioning. You may also see refrigeration included in HVAC as HVAC/R, HVACR, or HACR. HVAC systems utilize many different pieces of equipment, including but not limited to:

  • Air filters and prefilers
  • Heating/cooling coils
  • Heat exchangers
  • Supply fans
  • Humidification/dehumidification 
  • Ductwork
  • Dampers and actuators

HVAC systems are designed to maintain indoor thermal comfort, through heating and cooling, and indoor air quality for building occupants. 

Helpful resources for learning about HVAC systems

Many online resources provide in-depth explanations about HVAC systems for beginners and seasoned HVAC professionals alike. HVAC is a really broad topic, so we’ve listed some learning options below for people curious about HVAC. 

Why Is Ventilation and Air Filtration Crucial for IAQ?

As we mentioned above, one of the purposes of a building’s HVAC system is to maintain healthy indoor air quality. When discussing indoor air quality, the ‘ventilating’ part of the acronym is what we should be considering. 

Why is ventilation (including air filtration) crucial for maintaining good indoor air quality? Let’s take a look at three air quality pollutants: particulate matter, VOCs, and carbon dioxide. 

Particulate matter

Particulate matter pollution is an enormous problem all across the world. An estimated 91% of the world’s population lives in areas where air quality levels exceed WHO limits. 

As your HVAC system draws in outdoor air to supply the building, particulate matter can easily pollute the air inside (without even considering indoor sources of particulate matter). The air filters in your air handling unit (AHU) are designed to remove this particulate matter, and the amount and type of particulate matter that the filters remove will depend on the filter’s Minimum Efficiency Reporting Value (MERV) rating. 

For buildings located in highly polluted areas, the ventilation system’s air filters are the building’s best line of defense against particulate matter. 

Volatile organic compounds (VOCs)

Unlike particulate matter, the majority of which originates from the outdoors, volatile organic compounds (VOCs) are chemicals that are usually emitted by materials and products indoors. VOC concentrations can be reduced through indoor source control, replacing certain products with low-emitting alternatives. 

However, the easiest way to manage VOCs inside of buildings is the ventilation system. Increasing the supply of fresh, outdoor air dilutes indoor VOC concentrations to safe levels, and the VOCs are later exhausted through return vents. 

Carbon dioxide (CO2)

Carbon dioxide is technically not an air pollutant, but elevated indoor concentrations of carbon dioxide are still a concern for building occupants. 

Carbon dioxide has a very similar relationship with ventilation as VOCs do. Outdoor levels of carbon dioxide are generally much lower than indoor levels, so introducing more fresh air into the building will likewise reduce CO2 concentrations. 

Helpful HVAC and IAQ resources

For resources specifically related to indoor air quality and HVAC system design, we recommend checking out the articles listed below.

How IAQ Monitoring Streamlines HVAC System Operation

Since filtration and ventilation systems are key determinants of indoor air quality, why don’t all facility managers just max-out ventilation rates and air filter MERV ratings? Well, there are some major downsides to doing so. Pumping more air into the building will increase energy costs, and higher MERV rated filters can increase energy usage and stress on the system, potentially causing system breakdowns. We need to compromise between good indoor air quality and HVAC system efficiency. 

covid-19 map

When the COVID-19 pandemic began in 2020, HVAC systems swiftly became a key tool for reducing infection risks indoors. 

Air quality monitoring can help bridge the gap between these two goals. On the one hand, indoor air quality monitors, like the Sensedge or Sensedge Mini, will provide accurate air quality readings so you know the state of the air in the building. Since one of the main purposes of a building’s HVAC system is to maintain good air quality, having air quality data will ensure that the HVAC system is fulfilling its purpose. This is especially critical given the COVID-19 pandemic; ventilation and air filtration are key strategies for reducing the risk of COVID-19 spreading, and air quality monitoring can help you assess the efficacy of these strategies

On the other hand, air quality data can help you run the building’s HVAC system more efficiently. These efficiencies relate to ventilation rates and air filtration. 

Ventilation rates & air quality sensors

Demand controlled ventilation (DCV) is one common way to leverage air quality data in the running of HVAC systems. With DCV, carbon dioxide (CO2) sensors estimate occupancy by measuring the amount of CO2 in a space, and this occupancy rate determines the amount of air supplied to that space. In a variable air volume (VAV) ventilation system, unoccupied rooms will be supplied with less air than occupied spaces, cutting down on unnecessary energy usage.

DCV saves an average of 17.8% on energy across all U.S climate zones compared to simple occupancy for lighting alone. Not only does DCV save energy, but the CO2 readings also ensure that building occupants remain unaffected by elevated concentrations of carbon dioxide. 

Air filtration & air quality sensors

Particulate matter readings can provide actionable information about your HVAC system's air filters. In commercial ventilation systems, MERV ratings indicate the efficiency of air filters. The higher the MERV rating, the greater the amount of particulate matter removed from the air passing through the filter. High efficiency filters have higher pressure drops, which can increase energy costs.

If indoor particulate matter levels are high, this is a good indication that you may need to invest in air filters with a higher MERV rating. If your indoor particulate matter levels are good to go, however, this indicates that you could utilize a lower-efficiency air filter and save on energy.


Data provided by air quality sensors can not only unlock the combined benefits of greater efficiency and better indoor air quality through HVAC optimizations, but also help you earn building certifications and boost occupant wellness. For more information about the benefits of air quality monitoring, we recommend checking out our 2021 Air Quality Monitoring Guide for Businesses

You Air Quality Monitoring Solutions: The Sensedge and Sensedge Mini

Kaiterra’s Sensedge and Sensedge Mini are powerful air quality monitoring devices that you can use to optimize your HVAC system and promote a healthy indoor environment. Both devices feature:

  • A comprehensive selection of air quality sensing parameters
  • Flexible power, connectivity, and installation options
  • Modular designs that make recalibration quick and convenient

Contact our team below for more information about our commercial air quality monitoring solutions:

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Kaiterra is a global company on a mission to end air pollution. We make air monitors that empower people to make small changes in their everyday lives and help with researchers, NGOs, and governments around the world to end air pollution at the source.