Air Systems allow engineers to create and customize the wide range of air handling systems used in HVAC design. This includes Air Handling Units (AHU), Dedicated Outdoor Air Systems (DOAS), Energy Recovery Ventilators (ERV), fan only systems and more. There is a wide range of settings and controls for these design elements which are summarized here. More details on inputs can be found by following the relevant links.

User Interface Guide

Air System Details

  • Name: This is the title for the system. It must be unique.

  • Energy Code: This field describes the energy code associated with the system, if applicable.

  • Air System Type: This is the general type of the air system, used for easy organization

  • Description: Notes about the air system

  • Creator: This is the owner of the air system, it will be auto assigned when created

  • Source: The Firm name who created the original air system

  • Template: Reference to the original template used to generate the air system

  • Number of Zones: The total number of zones assigned to this air system

  • Area Served: The total area of the project served by the air system

Air Flow Parameters

  • Min Outdoor Rate [CFM (IP) | L/S (SI)]: The minimum outdoor air requirement for the system. Defaults to Autosized

  • Max Outdoor Rate [CFM (IP) | L/S (SI)]: The maximum outdoor air requirement for the system. Defaults to Autosized

  • Min Supply Air Rate [CFM (IP) | L/S (SI)]: The minimum supply air requirement for the system. Defaults to Autosized

  • Max Supply Air Rate [CFM (IP) | L/S (SI)]: the maximum supply air requirement for the system. Defaults to Autosized

    See Air Flow Parameter Details for more information and explanation of autosizing methods.

  • Supply Fan Type: Types available are currently variable and constant

  • Relief Fan Type: Types available are currently variable and constant

  • Supply Fan Location: Options are Blow-through and Draw-through

  • Relief Fan Location: Options are Return and Exhaust

    See Fan Details for definitions of the locations and their impact to sizing

Economizer Parameters

Control Type: Options are Fixed Enthalpy, Fixed Dry Bulb or -- (none)

Enthalpy Max Limit [Btu/lb (IP) | J/Kg (SI)]: The numeric value for enthalpy limit

Dry Bulb Max Limit [°F (IP) | °C (SI)]: the numeric value for dry bulb limit

Primary Heating Coil Configuration

  • Coil Type: Options are Hydronic, Electric, Gas, DX (Direct Expansion), and -- for none

  • Air Inlet/Outlet Temp [°F (IP) | °C (SI)]: The entering and leaving air temperatures of the coil. The default Inlet temperature is read from the Winter Design Day

  • Fluid Inlet/Outlet Temp [°F (IP) | °C (SI)]: The entering and leaving fluid temperatures of the coil. By default these are assigned per the Heating Source Mechanical Plant.

  • Rated Capacity [Btu/h (IP) | Watts (SI): Default is Autosized, however the value can be manually assigned.

  • Heating Source: The Mechanical Plant acting as the heat source for this coil. For version 2 of the platform this is fixed as an Ideal Heating Loop

Primary Cooling Coil Configuration

  • Coil Type: Options are Hydronic, DX (Direct Expansion), and -- for none

  • Entering Air Dry Bulb and Wet Bulb [°F (IP) | °C (SI)]: The entering air conditions of the coil. The default entering temperature is read from the Summer Design Day

  • Leaving Air Dry Bulb and Wet Bulb [°F (IP) | °C (SI)]: The leaving air conditions of the coil.

  • Fluid Inlet/Outlet Temp [°F (IP) | °C (SI)]: The entering and leaving fluid temperatures of the coil. By default these are assigned per the Cooling Source Mechanical Plant.

  • Rated Capacity [Btu/h (IP) | Watts (SI)]: Default is Autosized, however the value can be manually assigned.

  • Cooling Source: The Mechanical Plant acting as the cooling source for this coil. For version 2 of the platform this is fixed as an Ideal Cooling Loop

Energy Recovery

  • Type: Options are Plate, Rotary or -- for none

  • Sensible Heating %: Effectiveness of sensible heat exchange at 100% capacity and ARI standard conditions for heating

  • Latent Heating %: Effectiveness of latent heat exchange at 100% capacity and ARI standard conditions for heating

  • Sensible Cooling %: Effectiveness of sensible heat exchange at 100% capacity and ARI standard conditions for cooling

  • Latent Cooling %: Effectiveness of latent heat exchange at 100% capacity and ARI standard conditions for cooling

  • Frost Control: Options are Exhaust Air Recirculation, Exhaust Only, Minimum Exhaust Temperature or -- for none.

  • Economizer Bypass: Yes or no. When yes, the recovery device is bypassed or off at times the air side economizer is active

  • Nominal Power [Watts]: The electrical power required to operate the energy recovery device. This can be for controls, and/or motors associated with the device

    See Air Side Energy Recovery for more information

Zone Terminal Units

  • Terminal Unit Type: Options are VAV with Hydronic Reheat, CAV with Hydronic Reheat, VAV with Electric Reheat, CAV with Electric Reheat and -- for none.

  • Rated Inlet Temp [°F (IP) | °C (SI)]: The inlet temperature used for sizing coils, typically this equals the leaving air temperature of the central air system.

  • Max Outlet Temp [°F (IP) | °C (SI)]: The maximum allowed leaving air temperature of the zone terminal unit. Typically this should be no more than 15°F (8°C) above the zone set point.

  • Fluid Inlet/Outlet Temp [°F (IP) | °C (SI)]: The entering and leaving fluid temperatures of the coil. By default these are assigned per the Heating Source Mechanical Plant.

  • Rated Capacity [Btu/h (IP) | Watts (SI): Default is Autosized, however the value can be manually assigned.

  • Heating Source: The Mechanical Plant acting as the heat source for this coil. For version 2 of the platform this is fixed as an Ideal Heating Loop

Control Parameters

  • System Availability Schedule: Schedule of operation for the system, this can be any Other type schedule within the project.

  • System Night Cycle: Options are Cycle on full system if heating or cooling required, Follow the HVAC operation schedule, Cycle on zone terminal units if heating or cooling required, or -- for none. The night cycle defines system behavior when at setback.

  • Demand Control Ventilation: On/off toggle for system level DCV

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