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HVAC Templates

New users to EnergyPlus need to learn many things to understand how to create detailed input objects for modeling an HVAC system. In order to reduce this initial effort, HVACTemplates were created. Unlike other input objects, the HVACTemplate input objects are not directly processed by EnergyPlus; instead, a preprocessor called ExpandObjects turns these HVACTemplate input objects into the detailed HVAC input objects. This can be used as a learning tool since you can review the .expidf file that contains the detailed input objects or it can be used for long term modeling especially if your focus is not on HVAC related energy efficiency measures. The primary disadvantage of using the HVACTemplate input objects is that only a small subset of possible configurations can be modeled using them; however, the subset of configurations supported by the HVACTemplate input objects was carefully chosen to be some of the most common HVAC configurations. If the HVACTemplate input objects do not support the HVAC configuration you are considering; you need to model it with the detailed HVAC EnergyPlus input objects. When using HVACTemplate input objects, no regular EnergyPlus input objects related to HVAC should be used (see the InputOutputReference for some exceptions to this). The HVACTemplates can model:

  • Baseboard heating systems with optional hot water boiler
  • Fan coil systems with boilers and chillers
  • Packaged terminal air conditioner (PTAC) system with optional hot water boiler
  • Packaged terminal air-to-air heat pump (PTHP) systems
  • Water to air heat pumps with boiler and cooling tower
  • Variable refrigerant flow heat pumps (air-to-air)
  • Variable refrigerant flow heat pumps (water-to-air) with boiler and cooling tower
  • Direct-expansion (DX) cooling, package and split systems
  • Direct-expansion (DX) heat pump systems
  • Packaged variable air volume system using direct-expansion cooling
  • Variable air volume systems with boilers and air-cooled chillers
  • Variable air volume systems with boilers and water-cooled chillers
  • Constant air volume systems with boilers and water-cooled chillers
  • Dual-duct systems (constant or variable air volume) with boilers and water-cooled chillers
  • Dedicated outdoor air systems (DOAS) combined with zonal template systems

The Input Output Reference includes a list of exactly which input objects are needed for each of these configurations

  • HVACTemplate:Thermostat - describes the heating and cooling setpoints for a thermostat. This input object can be referenced by multiple HVACTemplate:Zone input objects if all the zones have the same setpoints.
  • HVACTemplate:Zone:IdealLoadsAirSystem - provides an idealized system that supplies air to the zone that meets all loads and uses no energy. Best used for load calculations.
  • HVACTemplate:Zone:BaseboardHeat - allows the simulation of electric or hot water thermostatically controlled baseboard heaters.
  • HVACTemplate:Zone:FanCoil - describes a four-pipe fan coil system with outdoor air intake.
  • HVACTemplate:Zone:PTAC - models a packaged terminal air conditioner with either electric, gas or hot water heating coil most commonly used in residential or hotel applications.
  • HVACTemplate:Zone:PTHP - models a packaged terminal heat pump system most commonly used in residential or hotel applications with either electric or gas supplementary heater.
  • HVACTemplate:Zone:WaterToAirHeatPump - describes the distributed "terminal" portions of a system which uses a medium temperature loop and heat pumps to provide heating and cooling to the building (also see HVACTemplate:Plant:MixedWaterLoop).
  • HVACTemplate:Zone:VRF - provides input for variable refrigerant flow terminal units.
  • HVACTemplate:Zone:Unitary - describes a constant volume direct-expansion system such as a rooftop system or split system. Often paired with a single HVACTemplate:System:Unitary for a single zone system but can also be part of a multizone system.
  • HVACTemplate:Zone:VAV - simulates the terminal of a variable air volume system with reheat.
  • HVACTemplate:Zone:VAV:FanPowered - simulates either a parallel or series fan power terminal of a variable air volume system.
  • HVACTemplate:Zone:VAV:HeatAndCool - simulates the terminal of a variable air volume system.
  • HVACTemplate:Zone:ConstantVolume - simulates the terminal of a constant air volume system.
  • HVACTemplate:Zone:DualDuct - simulates the zone portion of a constant volume or variable volume dual-duct HVAC system.
  • HVACTemplate:System:VRF - simulates the variable refrigerant flow system.
  • HVACTemplate:System:Unitary - describes the system portion of a rooftop or split DX cooling system with electric, gas or hot water heating.
  • HVACTemplate:System:UnitaryHeatPump:AirToAir - details the system portion of a rooftop or split DX air-to-air heat pump system.
  • HVACTemplate:System:UnitarySystem - models the system portion of a rooftop or split system and has more flexibility than the previous two input objects.
  • HVACTemplate:System:VAV - simulates the system portion of a variable air volume HVAC configuration with chilled water cooling and several different heating options.
  • HVACTemplate:System:PackagedVAV - describes the system portion of a packaged direct-expansion (DX) based variable air volume HVAC configuration with several different heating options.
  • HVACTemplate:System:ConstantVolume - provides input for the system portion of a constant air volume HVAC configuration with optional chilled water cooling and several different heating options.
  • HVACTemplate:System:DualDuct - models the system portion of a constant air volume or variable air volume dual-duct HVAC configuration with optional chilled water cooling and several different heating options.
  • HVACTemplate:System:DedicatedOutdoorAir - adds a dedicated outdoor air system (DOAS) which can be used with several of the HVACTemplate:Zone input objects and contains heating and cooling coils and heat recovery.
  • HVACTemplate:Plant:ChilledWaterLoop - models the chilled water loop connecting chillers to chilled water coils as well as the condenser water loop that connects chillers with cooling towers.
  • HVACTemplate:Plant:Chiller - describes a vapor-compression chiller that provides chilled water to the loop.
  • HVACTemplate:Plant:Tower - models an evaporative cooling tower used to reject heat from chillers.
  • HVACTemplate:Plant:HotWaterLoop - models the hot water loop connecting boilers to hot water coils.
  • HVACTemplate:Plant:Boiler - models a boiler that provides hot water to the loop.
  • HVACTemplate:Plant:MixedWaterLoop - models the medium temperature loop that serves water-to-air heat pumps as well as cooling towers and boilers.

In addition, this group of input objects includes three plant input objects that allow the referencing of chillers, towers, and boilers respectively so that additional details can be described in those input objects. Example for these are in the ExampleFiles directory and start with the name HVACTempate. All of these are described in the "Input/Output Reference" document under the Group "HVACTemplates" and please note that this group is described in Chapter 2 while most of the other groups of input objects are described in Chapter 1. The expansion process is described in the Auxiliary Programs document under "ExpandObjects."