Discover the essential factors and best practices for designing high-performance AHUs that enhance indoor air quality, energy efficiency, and occupant comfort in various construction environments.
One of the critical challenges faced in cold climates is snow entrainment, which occurs when fluffy snow is carried into the airstream. At airflow velocities as low as 50 feet per minute (fpm), snow can be drawn into the system, potentially leading to operational inefficiencies, water accumulation, and even airflow stoppages.
Since completely eliminating snow entrainment is impossible, the focus should be on effective management strategies:
Moisture carry-over occurs when condensation from components such as cooling coils, heat recovery devices, and humidifiers is picked up by the airstream and transported downstream. If not managed properly, this can lead to corrosion, flooded plenums, water damage to building structures, and even compromised air quality.
To mitigate these risks, consider the following:
Minimizing Air Stratification
Stratification occurs when multiple air streams—such as outdoor air (OA) and return air (RA)—do not mix effectively, leading to temperature inconsistencies and reduced coil efficiency. Poor air mixing can result in sensor errors, inefficient heating or cooling, and discomfort in conditioned spaces.
Best practices to avoid stratification include:
Noise control is an essential aspect of AHU design, particularly in applications such as hospitals, offices, and residential buildings where excessive sound levels can cause discomfort. Since fans are the primary noise source, selecting the right fan type and implementing sound attenuation measures is key.
Sound mitigation strategies include:
Ensuring Proper Clearance for Maintenance and Testing
Proper clearances around an AHU are essential for maintenance accessibility, component removal, and electrical servicing. Insufficient space can lead to operational inefficiencies and increased maintenance costs.
Key clearance considerations include:
Conclusion
Optimizing AHU design is a multi-faceted process that requires careful consideration of environmental factors, system layout, component selection, and maintenance accessibility. By implementing best practices for managing snow entrainment, moisture carry-over, stratification, sound attenuation, and clearances, HVAC professionals can enhance the efficiency, reliability, and longevity of AHU systems.
Investing in high-quality AHU design not only improves energy efficiency and occupant comfort but also reduces long-term operational and maintenance costs. By leveraging these insights, HVAC engineers and facility managers can make informed decisions that lead to better-performing air handling systems.