What is FAHU (Fresh Air Handling Unit) in HVAC?

In the realm of HVAC (Heating, Ventilation, and Air Conditioning) systems, technological evolutions have been made to these systems to enhance comfort quality for their users. FAHU (Fresh Air Handling Unit) is one such technological evolution that has caught the attention of the industry. This system is designed as a part of the HVAC unit to enhance indoor air quality and ensure energy efficiency. This article will discuss what is FAHU in HVAC. And what are its characteristics and application?

What is FAHU?

FAHU which is short for Fresh Air Handling Unit is somewhat similar to AHU (Air Handling Unit) except it doesn’t recirculate the air in the habitat. So,

“A Fresh Air Handling Unit (FAHU) is specialized HVAC equipment designed to supply the fresh outdoor air to the living spaces, filter and condition the air, and distribute that air to indoor spaces.”

These units primarily held the responsibility of instigating the fresh air and then retreating it before letting it enter the building. Unlike traditional systems, these systems don’t use the same air twice for reheating or cooling the space as their sole purpose is to provide fresh air on the premises. 

Working of FAHU

Your FAHU goes through this process to provide you with fresh air:

Air Intake: Louvers or Dampers located on the exterior of the FAHU let the fresh air into the system. The amount of entering air is controlled based on indoor air quality and outdoor conditions.

Pre-Filtration: this step allows the filters to capture large particles like dirt, dust, debris, and pollen before it enters the main part of the FAHU. This saves the system from clogging sensitive downstream filters.

Main Filtration: Pre Filtered Air now enters the Main Filter which removes finer particles like allergens and contaminants through HEPA filters or High-rated MERV filters ensuring supreme quality of air.

Heat Exchange (if applicable): Heat exchangers in the FAHU ensure the transfer of heat between incoming fresh air and outgoing exhaust air without mixing them. It results in the cooling of the warm air in summer and the heating of the cold air in winter.

Air Conditioning and Humidity Control: The air now passes through cooling coils or heating coils according to the desired temperature. Humidifiers and Dehumidifiers are also integrated into the system to control the humidity levels.

Supply Fan Operation: The conditioned and treated air is then propelled by a supply fan. This fan creates a positive pressure within the FAHU system, forcing the air through the ductwork and into the building’s indoor spaces.

Distribution: The conditioned air is now supplied evenly through the ductwork to various rooms and other living spaces.

Exhaust: Some FAHU systems include an exhaust fan that pushes the stale air out into the environment and maintains comfort levels in the house.

Control and Automation: Several Parameters monitor the whole process like temperature, humidity, and air quality. These servers inform the control systems to adjust the temperature indoors accordingly. This system also looks for outdoor weather conditions to provide optimum performance.

Characteristics of FAHU:

Fresh Air Handling Units possess many characteristics that differentiate them from other units.

Air Cleaning:

These systems are capable of removing pollutants, particulates, and contaminants from the air. Their advanced filtration technology ensures the rotation of clean and fresh air in the atmosphere.

Separate Heat Canals:

One of their distinct characteristics is their heat recovery mechanism. Their heat exchangers can transfer the heat between the fresh incoming air and the exhaust air. This pre-conditioning of air results in reduced energy consumption.

Humidity Control:

FAHU can regulate the air to control the humidity in the indoor space. Different humidity levels can be achieved according to conditioning needs.

Energy Efficiency:

These units are considered energy-efficient because of their excellent utilization of heat recovery systems, variable speed drives, and advanced control algorithms that allow them to optimize the unit’s performance according to the space’s requirements.

Control Systems:

Some of the modern FAHUs are equipped with sophisticated control systems that can control monitoring, adjustment, and automation of the unit. You can have precise control over indoor air quality and comfort levels this way.

Customization:

These units are customizable. They come in different sizes and configurations and you can design one that is specific to your needs. This made them applicable in wide industries.

Regulatory Compliance:

One commendable characteristic of Fresh Air Handling Units is their compliance with the building codes and standards related to indoor air and ventilation.

Applications of FAHU

• Commercial Buildings: Office, Retail Stores, Restaurants, Hotels 
• Healthcare Facilities: Operating rooms, Isolation rooms, Patient wards (Recirculation of air is not preferred in hospitals due to germs and bacteria affected air)
• Industrial Settings: Medicine Industry
• Educational Institutes: Classrooms, Libraries, Auditoriums
• Residential Complexes and Data Centers

Fresh Air Handling Units (FAHUs) have emerged as indispensable components in modern HVAC systems. Their ability to deliver clean, conditioned, and fresh outdoor air to indoor spaces while enhancing energy efficiency and indoor air quality makes them a cornerstone of comfortable and healthy environments in various sectors, including commercial, residential, industrial, and healthcare. As technology continues to advance, FAHUs are likely to evolve further, contributing to more sustainable and pleasant indoor environments.