How to Use the AHU Calculator

Overview

This section provides an overview of how to effectively use the AHU Calculator application.

Steps to Use the AHU Calculator

AHU Calculator Guide
  1. Login: Access the application by logging into your account.
  2. Click "AHU Calculator" on the Navigation bar.
  3. Select the appropriate application type: Choose the mode that suits your design needs. Please review the usage details of each mode before proceeding.
  4. Enter project input details: Fill in the required information about your project.
  5. Select calculation units: Choose between IP and SI units. By default, the mode is set to Cooling & Dehumidification.
  6. Input parameters: Provide the necessary data for the calculation process.
  7. Click "Calculate": Execute the calculation and view the results.

Notes on the Application

  • Applicable for chilled water coils (not compatible with glycol-based fluids or DX coils).
  • Air cooling and dehumidifying coils are multi-row, designed for counterflow arrangements.
  • Coil's face air velocity: ~ 2.5m/s
  • Coil's WPD: <= 65kPa
  • Designed for full load conditions; for part load control, please contact us for advice.
  • The "Cooling & Dehumidification" mode is suitable for hot and humid climates during summer.
  • The air system schematic shown in this application primarily illustrates the main components, such as the cooling/heating coil, DH, HRW, etc. Please note that a complete air distribution system also includes other components, both inside and outside the AHU, such as filters (primary, secondary, HEPA, ULPA, etc.), UV light/silencer (if required), and control instruments—including sensors, dampers, and valves—which are all part of the control system.

Note: While this software provides a relative simulation of actual coil performance, we cannot guarantee accuracy for all scenarios (especially exceptions). It is highly recommended to cross-check results with proprietary selection software from coil manufacturers.

Cooling Mode 1.1

Cooling Mode 1.1 is suitable for applications that use only the main cooling coil for room air conditioning.

The initial interface of Cooling Mode 1.1 (with some default values that you can customize):

Cooling11_1 Guide

Steps to perform:

  • Select Cooling Mode 1.1
  • Enter input data for the calculation process
  • Click "Calculate"

Interface after calculation:

Cooling11_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, RA: Return air, EA: Exhaust air, MA: Mixing air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)

Cooling Mode 1.2

Cooling mode 1.2 is suitable for applications that use a combination of a pre-cooling coil to handle the fresh air heat load (down to the room dew point) and a main cooling coil to handle the remaining heat load.

The initial interface of Cooling Mode 1.2 (with some default values that you can customize):

Cooling12_1 Guide

Steps to perform:

  • Select Cooling Mode 1.2
  • Enter input data for the calculation process
  • Click "Calculate"

Interface after calculation:

Cooling12_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, RA: Return air, EA: Exhaust air, MA: Mixing air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)

Cooling Mode 1.3

Cooling mode 1.3 is suitable for applications that use only the main cooling coil for room air conditioning. This configuration requires 100% fresh air to be supplied to the room (i.e., no room air recirculation)

The initial interface of Cooling Mode 1.3 (with some default values that you can customize):

Cooling13_1 Guide

Steps to perform:

  • Select Cooling Mode 1.3
  • Enter input data for the calculation process
  • Click "Calculate"

Interface after calculation:

Cooling13_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, EA: Exhaust air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)

Cooling Mode 2.1

Cooling mode 2.1 is suitable for applications that require both room temperature and humidity control. The pre-cooling coil handles the total fresh air latent heat and room latent heat, while the main cooling coil handles the remaining sensible heat load.

The initial interface of Cooling Mode 2.1 (with some default values that you can customize):

Cooling21_1 Guide

Steps to perform:

  • Select Cooling Mode 2.1
  • Enter input data for the calculation process
  • Click "Calculate"

Interface after calculation:

Cooling21_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, RA: Return air, EA: Exhaust air, MA: Mixing air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)

Cooling Mode 2.2

Cooling mode 2.2 is suitable for applications that require room temperature and humidity control (CAV system). The cooling coil handles the total heat load at full load, while the heating coil reheats the air at part load.

The initial interface of Cooling Mode 2.2 (with some default values that you can customize):

Cooling22_1 Guide

Steps to perform:

  • Select Cooling Mode 2.2
  • Enter input data for the calculation process
  • Click "Calculate"

Interface after calculation:

Cooling22_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, RA: Return air, EA: Exhaust air, MA: Mixing air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity, HC: Heating coil/ Heating capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)

Cooling Mode 2.3

Cooling mode 2.3 is suitable for applications that require both room temperature and humidity control, especially for low dew point room conditions (< 0.007 kgw/kgda). A desiccant wheel is used to handle the total fresh air latent heat and room latent heat, while the main cooling coil handles the remaining sensible heat load.

The initial interface of Cooling Mode 2.3 (with some default values that you can customize):

Cooling23_1 Guide

Steps to perform:

  • Select Cooling Mode 2.3
  • Enter input data for the calculation process. For the Desiccant wheel, you need to enter the air flow through the DH and the leaving DH air condition that match the model you have chosen to ensure practicality
  • Click "Calculate"

Interface after calculation:

Cooling23_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, RA: Return air, EA: Exhaust air, MA: Mixing air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • DH: Desiccant Wheel, RqLH: required latent heat, SeLH: selected latent heat, SeM: selected moisture
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)

Cooling Mode 3.1

Cooling Mode 3.1 is suitable for applications that require both sensible and latent energy recovery from room exhaust air (using an energy recovery wheel to reduce the dry-bulb temperature and humidity ratio of fresh air). After that, the pre-cooling coil continues to handle the fresh air heat load (down to the room dew point), and the main cooling coil handles the remaining heat load.

The initial interface of Cooling Mode 3.1 (with some default values that you can customize):

Cooling31_1 Guide

Steps to perform:

  • Select Cooling Mode 3.1
  • Enter input data for the calculation process
  • Click "Calculate"

Interface after calculation:

Cooling31_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, RA: Return air, EA: Exhaust air, MA: Mixing air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • HRW: Energy recovery wheel, Eff_total/ Eff_sensible: HRW efficency
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)

Cooling Mode 3.2

Cooling Mode 3.2 is suitable for applications that require both sensible and latent energy recovery from room exhaust air (using an energy recovery wheel to reduce the dry-bulb temperature and humidity ratio of fresh air). The main cooling coil handles the remaining heat load.

The initial interface of Cooling Mode 3.2 (with some default values that you can customize):

Cooling32_1 Guide

Steps to perform:

  • Select Cooling Mode 3.2
  • Enter input data for the calculation process
  • Click "Calculate"

Interface after calculation:

Cooling32_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, RA: Return air, EA: Exhaust air, MA: Mixing air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • HRW: Energy recovery wheel, Eff_total/ Eff_sensible: HRW efficency
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)

Cooling Mode 3.3

Cooling Mode 3.3 is suitable for applications that require only sensible energy recovery from room exhaust air (using a plate heat exchanger to reduce the dry-bulb temperature of fresh air). After that, the pre-cooling coil continues to handle the fresh air heat load (down to the room dew point), and the main cooling coil handles the remaining heat load.

The initial interface of Cooling Mode 3.3 (with some default values that you can customize):

Cooling33_1 Guide

Steps to perform:

  • Select Cooling Mode 3.3
  • Enter input data for the calculation process
  • Click "Calculate"

Interface after calculation:

Cooling33_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, RA: Return air, EA: Exhaust air, MA: Mixing air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • HRW: Plate heat exchanger, Eff_total/ Eff_sensible: HRW efficency
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)

Cooling Mode 3.4

Cooling Mode 3.4 is suitable for applications that require only sensible energy recovery from room exhaust air (using a plate heat exchanger to reduce the dry-bulb temperature of fresh air). The main cooling coil handles the remaining heat load.

The initial interface of Cooling Mode 3.4 (with some default values that you can customize):

Cooling34_1 Guide

Steps to perform:

  • Select Cooling Mode 3.4
  • Enter input data for the calculation process
  • Click "Calculate"

Interface after calculation:

Cooling34_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, RA: Return air, EA: Exhaust air, MA: Mixing air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • HRW: Plate heat exchanger, Eff_total/ Eff_sensible: HRW efficency
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)

Cooling Mode 4.1

Cooling Mode 4.1 is suitable for applications that require a constant air change rate per hour (ACH) for a cleanroom (this ACH is higher than the required ACH for the total heat load). The cooling coil handles both total latent heat and sensible heat, while the heating coil reheats the air to control the room air conditions.

The initial interface of Cooling Mode 4.1 (with some default values that you can customize):

Cooling41_1 Guide

Steps to perform:

  • Select Cooling Mode 4.1
  • Enter input data for the calculation process
  • Click "Calculate"

Interface after calculation:

Cooling41_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, RA: Return air, EA: Exhaust air, MA: Mixing air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity, HC: Heating coil/ Heating capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)

Cooling Mode 4.2

Cooling Mode 4.2 is suitable for applications that require a constant air change rate per hour (ACH) for a cleanroom (this ACH is much higher than the required ACH for the total heat load). To avoid excessive airflow through the cooling coil, a bypass air method is applied (this configuration uses a return air bypass). The cooling coil handles the necessary total latent and sensible heat, while the heating coil reheats the air to control the room air conditions at part load. You can eliminate the heating coil if the bypass airflow is actively controlled using motorized dampers.

The initial interface of Cooling Mode 4.2 (with some default values that you can customize):

Cooling42_1 Guide

Steps to perform:

  • Select Cooling Mode 4.2
  • Enter input data for the calculation process
  • Click "Calculate"

Interface after calculation:

Cooling42_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, RA: Return air, EA: Exhaust air, MA: Mixing air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity, HC: Heating coil/ Heating capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)

Cooling Mode 4.3

Cooling Mode 4.3 is suitable for applications that require a constant air change rate per hour (ACH) for a cleanroom (this ACH is much higher than the required ACH for the total heat load). To avoid excessive airflow through the cooling coil, a bypass air method is applied (this configuration uses a mixing air bypass). The cooling coil handles the necessary total latent and sensible heat, while the heating coil reheats the air to control the room air conditions at part load. You can eliminate the heating coil if the bypass airflow is actively controlled using motorized dampers.

The initial interface of Cooling Mode 4.3 (with some default values that you can customize):

Cooling43_1 Guide

Steps to perform:

  • Select Cooling Mode 4.3
  • Enter input data for the calculation process
  • Click "Calculate"

Interface after calculation:

Cooling43_2 Guide

Legends:

  • Red highlighted areas: Parameters that need to be entered
  • Orange highlighted areas: Default parameters set to 0, you can adjust if necessary
  • Green highlighted areas: Calculated parameters
  • OA/FA: Outdoor air/ Fresh air, RA: Return air, EA: Exhaust air, MA: Mixing air
  • SAF: Supply air fan, RAF: Return air fan (if available)
  • CC: Cooling coil, TCC: Total cooling capacity, SCC: Sensible cooling capacity, HC: Heating coil/ Heating capacity
  • EWT: Entering water temperature, LWT: Leaving water temperature
  • RTH: Room total heat, RSH: Room sensible heat, RSHF: Room sensible heat factor (RSHF=RSH/RTH)