An Air-Handling Unit Outside Next To A Green Bush

In the quest for sustainable building practices, AHU refurbishment has emerged as a cost-effective and efficient alternative to installing entirely new air handling units. This guide aims to shed light on the process of AHU refurbishment and explore its potential benefits.

What is an Air Handling Unit (AHU)?

Air Handling Units (AHUs) are integral to mechanical ventilation in buildings across the UK. These units draw fresh air from the outside, pass it through filters to purify it, and then heat or cool it using coils to achieve the desired indoor temperature. AHUs also play a crucial role in providing thermal comfort to occupants by regulating temperature and humidity.

New AHUs are now designed in accordance with Energy-related Products (ErP) regulations and incorporate heat recovery devices and more efficient EC fan technology. While modern AHUs are larger to accommodate improved energy efficiency, they offer greater sustainability and lower energy consumption.

The Importance of AHU Refurbishment

AHU refurbishment offers numerous advantages in terms of sustainability and energy efficiency:

  1. Cost-Effectiveness: Refurbishing existing AHUs is often more budget-friendly than purchasing new units, making it an attractive option for businesses seeking cost-effective solutions.
  2. Energy Efficiency: Upgrading components within the AHU casework, such as fans, filters, and coils, can significantly enhance the unit’s energy efficiency, resulting in reduced energy consumption and environmental impact.
  3. Extended Lifespan: Through extensive refurbishment, the life cycle of AHUs can be extended by up to 15 years when combined with regular Planned Preventative Maintenance (PPM) plans, making it a long-term sustainability measure.
  4. Improved Indoor Air Quality (IAQ): Upgrading filter banks and implementing air cleaning technologies like UV-C and Bipolar Ionisation can lead to better IAQ, ensuring healthier and more comfortable indoor environments.
  5. Access to Modern Technologies: Refurbished AHUs can accommodate modern technologies, such as retrofit cooling coils or air purification systems, further enhancing sustainability and IAQ.

Upgrading AHU Fans: Benefits and Considerations

Replacing traditional belt-driven centrifugal fans with EC plug fans brings numerous advantages:

  1. Increased Efficiency: EC plug fans are up to 30% more efficient than traditional fans, resulting in energy savings and quicker payback periods.
  2. Reduced Maintenance: Unlike belt-driven fans, EC plug fans have no belts or pulleys, eliminating the need for regular maintenance and allowing engineers to focus on other tasks.
  3. Space Savings: The compact design of EC fans allows room for retrofitting cooling coils or air purification technologies, maximising the use of available space.
  4. Enhanced Control: EC fans come with built-in speed controllers, enabling automatic adjustments by the Building Management System (BMS) for energy optimisation.

Optimising Air Flow within AHUs

Increasing air flow within an AHU must be done carefully to avoid compromising the functionality of its components:

  1. Design Velocity: Each component within the AHU has a design velocity that should not be exceeded to maintain optimal performance.
  2. Cooling Coil Implications: Increasing air velocity over cooling coils may require additional moisture eliminators and could reduce the coil’s cooling capacity, affecting indoor thermal comfort.

Consultation and Site Surveys

To determine whether AHU refurbishment is suitable for your building, it is essential to consult with experts and conduct full site surveys. Professionals, like those at Building Ventilation Solutions, can assess the potential for increased air flow and recommend the best course of action.


AHU refurbishment offers a compelling solution for building owners seeking sustainability, energy efficiency, and cost-effectiveness. By upgrading components and implementing modern technologies, AHUs can be revitalised, extending their life cycle and improving indoor air quality. If you are considering AHU refurbishment, contact the experts at Building Ventilation Solutions for tailored advice and solutions to meet your building’s needs and sustainability goals.