AHU (Air Handling Unit) Design Basics: A Beginner’s Guide-2024

by MEP Details
AHU (Air Handling Unit)

Introduction

The design guidelines and factors for an AHU Air Handling Unit is full foam for commercial or industrial HVAC systems are described in this document. Maintaining a building’s interior temperature, humidity levels, and air quality all depend heavily on the AHU.

AHU
(Air Handling Unit)

AHU (Air Handling Unit) Design Criteria

CapacityCalculated based on building size, occupancy, and cooling/heating load requirements.Cubic Feet per Minute (CFM)
Air QualityProvides adequate filtration to remove particulate matter, allergens, and contaminants from incoming air.NA
Temperature ControlCapable of heating or cooling air as per building’s needs, with precise temperature control.Degrees Celsius (°C) or Fahrenheit (°F)
Humidity ControlRegulates humidity levels within desired range for comfort and health.Percentage (%)
Energy EfficiencyDesign considerations include energy-efficient components and systems to minimize operational costs and environmental impact.NA
Noise LevelsIncorporates measures to reduce noise levels for occupant comfort.Decibels (dB)

AHU Components Basic Description

Air FiltersHigh-efficiency particulate air (HEPA) filters or equivalent for removing fine particles and allergens.
Heating/Cooling CoilsCoils connected to a heating or cooling source to adjust air temperature.
Humidifier/DehumidifierIntegrates a humidifier or dehumidifier as needed to control humidity levels based on climate and indoor conditions.
FansUtilizes centrifugal fans to circulate air through the AHU and building ductwork.
DampersMotorized dampers for controlling air flow within the AHU and adjusting airflow to different zones.
ControlsAn advanced control system, possibly with sensors, actuators, and a programmable logic controller (PLC).
InsulationProper insulation of ductwork and AHU components to minimize heat gain or loss and improve energy efficiency.
Sound AttenuatorsIncorporates sound attenuators or silencers to reduce noise levels generated by the AHU.

AHU Design Calculation

Calculation StepFormulaResult/Value
Building Area10,000 square feet10,000 sq ft
Occupancy50 people50 people
Sensible Cooling Load (Qs)Qs = Area × Occupancy × Sensible Heat Factor (SHF)375,000 Btu/hr
Air Volume (CFM)Air Volume (CFM) = Sensible Cooling Load (Btu/hr) ÷ (1.08 × Temperature Difference)17,361 CFM
AHU Capacity SelectionSelect an AHU capacity slightly higher than calculated value to ensure adequate cooling capacity18,000 CFM
VerificationOnce installed, commission and test AHU to meet cooling load requirementsVerify AHU performance
Note: The “Result/Value” column shows the numerical results or values obtained from each calculation step.

Types of Components with Photos

Direct Drive :

 All direct motor drive Air Handling Unit Blowers/Fans are supplied with suitable Electric motor with Fan cooling and also Flame Proof. In Air Handling Unit Blowers/Fans, Impeller are Directly mounted on Shaft of Electric motor. Electric motor in Direct drive Blowers are mounted on M.S. Fabricated Base Plate.

Belt Drive :

 All Belt driven Air Handling Unit Blowers/Fans are provided with EN-8 Steel shaft extension running in Ball bearing of different types like Pillow Block Pedestal, Sleeve Type Pedestal, Single bearing Type, etc. Air Handling Unit Blowers/Fans are provided with V type or Flat Pulley of suitable size. Complete Shaft and Bearing systems are mounted on M.

Cooling Coil ( DX & Chilled Water)

Filters HEPA / FINE / PRE Filter

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