Understanding the Limitations of Air Changes in HVAC Systems for Effective Air Purification

Indoor air quality is a crucial issue, especially as many people spend long hours indoors. Efficient heating, ventilation, and air conditioning (HVAC) systems play a significant role in creating a comfortable and healthy environment. However, relying solely on air changes as a measure for air purification can lead to misunderstandings about their effectiveness. This post delves into the limitations of air changes in standard HVAC systems and how they impact air purification.

The Importance of Air Changes

Air changes per hour (ACH) measures how many times the air in a room is replaced in an hour. It serves as a key indicator of ventilation effectiveness and is closely linked to indoor air quality. Generally, a higher ACH is tied to better air quality since it signifies a greater volume of fresh air entering a space.

However, while maintaining adequate ACH is important, it is only one piece of the puzzle affecting air purification. The type of HVAC system and the quality of air filtration play critical roles. According to the Environmental Protection Agency (EPA), indoor air can be two to five times more polluted than outdoor air. This statistic highlights the need to look beyond just ACH to improve air quality.

The Role of Filtration Systems

Many HVAC systems may lack high-efficiency particulate air (HEPA) filters or advanced filtration technologies. Standard filters often fail to capture smaller particles, like fine dust and pollen. For example, HEPA filters can trap 99.97% of particles that are 0.3 microns large, but most standard filters do not meet this benchmark. This limitation means that even with frequent air changes, harmful contaminants may still exist.

To bolster air purification efforts, integrating high-quality filters with a higher Minimum Efficiency Reporting Value (MERV) rating is essential. Choosing filters with MERV ratings of 13 or higher can capture smaller allergens and improve indoor air quality significantly.

Air Change Rates and Their Limitations

It's vital to recognize that a high air change rate does not always equate to better air quality. In some cases, bringing in outdoor air could introduce higher levels of pollutants, especially in urban areas. For instance, during rush hour, the air quality can deteriorate because of vehicle emissions. If an HVAC system is automatically increasing air changes during these times, it may exacerbate indoor pollution rather than alleviate it.

Moreover, in energy-efficient buildings that are tightly sealed, achieving an ideal ACH can be difficult. An overly sealed environment can lead to stale air, which is harmful to health. The American Lung Association stresses the importance of balanced ventilation to ensure fresh air circulation without compromising the integrity of the indoor environment.

Beyond Air Changes: The Authentic Need for UVC Germicidal Luminaires

Given the limitations of air changes in HVAC systems, considering supplemental air purification systems can be beneficial. Upper UVC Germicidal luminaires can capture all airborne contaminants effectively. Many Modern Upper UVC Germicidal luminaries are placed at ceiling height an emit a narrow band of light that does not shine downwards, which allow for daily movement

The use of UVC luminaires have become the additional solution to effectively purify the air, through air convection the number of air changes in a room exceed over 20 ACH per hour, and because the Luminaries are placed at ceiling height 100 percent of the air is captured, there it is the most effective way to purify an indoor space. the effectiveness of UVC is well established but what is not understood well is the movement of air and aerosol contamination.

The speed in which the infect a room is the same speed that the room is purified as this is driven by air convection. It is this reason why Upper Germicidal Luminaries are widely used in area such as Offices, Hospital waiting room, etc, is because it provides the most effective means of air purification and is safe, as the light does not chine down due to a patented design, that emits a narrow band of light.

Factors Influencing Effective Air Purification

Achieving optimal air purification goes beyond simply maintaining recommended air change rates. Several factors also play crucial roles:

1. Room Size and Configuration: The layout of the space impacts air circulation. Larger rooms or areas with obstacles may need extra air changes or purification methods to ensure consistent air quality throughout. For instance, a conference room with a capacity of 100 people may require more frequent air changes than a smaller office.

   
   

2. Occupancy Levels: Spaces with high occupancy generate more pollutants like carbon dioxide and volatile organic compounds (VOCs) from personal care products. For example, a room with 10 people can generate five times the CO2 levels compared to an empty room. Therefore, more air changes may be necessary to maintain healthy air quality in crowded settings.

   
   

3. The Nature of Contaminants: Different air pollutants demand different filtration strategies. Particulate matter can often be trapped with advanced filters, but gaseous pollutants may require specialised carbon-based filters for effective removal.

   
   

Regular Maintenance and System Checks

The effectiveness of an HVAC system hinges on the regular maintenance of its filters and components. Clogged filters can restrict airflow and reduce filtration efficiency, leading to poor air quality. For optimal performance, it is recommended to check and replace filters every 1 to 3 months, depending on usage.

Professional maintenance can also help spot issues that might be affecting air circulation and quality. Regular assessments ensure the HVAC system works correctly and that any necessary modifications are implemented to enhance air purification.

Final Thoughts

While air changes per hour serve as a useful measurement for evaluating indoor air quality, they are just one part of a broader equation that affects air purification. The limitations of standard HVAC systems can hinder their ability to significantly improve air quality. Therefore, additional strategies, such as advanced filtration systems and standalone air purifiers, should be considered.

Improving indoor air quality requires a comprehensive approach that considers room design, occupancy levels, and pollutant types. By addressing these elements, individuals and organisations can create healthier indoor environments that promote well-being.

Understanding the limitations of air changes in HVAC systems empowers decision-makers to take informed actions that positively affect air quality. By enhancing air purification efforts, a more comfortable and healthier indoor atmosphere can be achieved for everyone.

The most effective solution that is additional and negates the limitations of HVAC systems limited air changes is to place a UVC Germicidal luminarre in each room, where there is a high population of human traffic, it is inexpensive, effective and safe.