HVAC Air Details - [source code]
Use this component to set the parameters of a HVAC ventilation system (or air side) that has been assigned with the "HoneybeeAssign HVAC System" component. Not all of the inputs on this component are assignable features of all HVAC systems. However, most HVAC systems have these features and, if you assign a parameter that is not usable by a certain HVAC system, the "Honeybee_Assign HVAC System" component will give you a warning to let you know. -
Inputs
HVACAvailabiltySched [Default]
A text string representing the HVAC availability that you want to use. This can be either a shcedule from the schedule libirary or a CSV file path to a CSV schedule you created with the "Honeybee_Create CSV Schedule" component.fanTotalEfficiency [Default]
A number between 0 and 1 that represents the overall efficiency of the fan. Specifically, this is the ratio between the power delivered to the air fluid and the electrical power intput to the fan. It is the product of the motor efficiency and the impeller efficiency. The impeller efficiency is power delivered to the fluid (air) divided by the shaft power. The power delivered to the fluid is the mass flow rate of the air multiplied by the pressure rise divided by the air density. The default is usually between 0.6 and 0.7.fanMotorEfficiency [Default]
A number between 0 and 1 that represents the efficiency of the fan electric motor. The motor efficiency is the power delivered to the fan shaft divided by the electrical power input to the motor. This value must be greater than the fanTotalEfficiency above. The default is usually around 0.9.fanPressureRise [Default]
A number representing the pressure rise across the fan in Pascals. This is the pressure rise at full flow and standard (sea level) conditions (20°C and 101325 Pa). The default is usually around 500 Pa.fanPlacement [Default]
A boolean value that represents the placement of the fan in relation to cooling or heating coils. The default is set to True to draw through. Choose from the following options: True = Draw Through (the fan comes after the coils such that air is drawn by the fan across the heating/cooling coils). False = Blow Through (the fan comes before the coils such that air is blown through the heating/cooling coils).airSystemHardSize [Optional]
A number that represents airflow in m3/s and sets the maximum air flow through the HVAC air system including the fan and ducts. This overrides the default autosizing of the air system is useful for evaluating strategies like larger ducts to minimize friction and decrease fan energy use. It's particularly useful in cases of vetilation-dominated spaces like labs and hospital patient rooms.centralAirLoop [Optional]
Set to "True" to have all instances of this HVAC Type have a single central air loop. If set to False or left blank, each branch of a HBZone data tree that is plugged into this component will have a separate air loop.demandControlledVent [Optional]
A boolean value that represents whether system can vary its speed and the volume of air to match occupancy. The default is False for all systems. Choose from the following options: True = Demand Controlled Varialbe Minimum Air (the system can vary the volume of air to match occupancy). False = Constant Volume Minimum Air (the fan has only one miniumum flow rate when it is on).heatingSupplyAirTemp [Default]
A number representing the target temperature of the supply air when the system is in heating mode. For large systems, this is the rated outlet air temperature of the heating coil. Default for a VAV system is 35C. Default for ideal air is 40 C.coolingSupplyAirTemp [Default]
A number representing the target temperature of the supply air when the system is in cooling mode. For large systems, this is the rated outlet air temperature of the cooling coil. Default is typically around 12C, which is the coldest temperature before supply air can cause clear thermal discomfort issues. Default for ideal air is 13 C.airRecirculation [Optional]
An optional boolean that, when set to False, will make all air pass through the air loop only once without recirculation. The default is set to True, which will recirculate air when the air needed to meet heating/cooling loads is in excess of the minimum outdoor ventilation. The only reasons why this output might be set to False is for systems where outdoor air intake and exhaust cannot be located close enough to allow for recirculation or one is modeling a space like a laboratory where the exhaust is toxic and cannot be recirculated. Note that this input will have no effect on HVAC systems with a DOAS since this system isn't intedned to heat and cool the space.airsideEconomizer [Optional]
An integer or boolean value (0/1) that sets the economizer on the HVAC system. The default is set to "True" or "1" to include a Differential Dry Bulb air side economizer or "2" for a Differential Enthalpy economizer if the zone has humidity control. Choose from the following options: 0 - No Economizer - The HVAC system will constantly provide the same amount of minimum outdoor air and may run the cooling system to remove heat and meet thermostat setpoints. 1 - Differential Dry Bulb - The HVAC system will increase the outdoor air flow rate when there is a cooling load and the outdoor air temperature is below the temperature of the return (or exhaust) air. 2 - Differential Enthalpy - The HVAC system will increase the outdoor air flow rate when there is a cooling load and the outdoor air enthalpy is below that of the return (or exhaust) air. 3 - Fixed Dry Bulb - The HVAC system will increase the outdoor air flow rate when there is a cooling load and the outdoor air temperature is below a specified dry bulb temperature limit (default is 28C). 4 - Fixed Enthalpy - The HVAC system will increase the outdoor air flow rate when there is a cooling load and the outdoor air enthalpy is below a specified enthalpy limit (default is 64000 J/kg). 5 - Electronic Enthalpy - The HVAC system will calculate the humidity ratio limit of the outdoor air based on the dry-bulb temperature of outdoor air and a quadratic/cubic curve, and compare it to the actual outdoor air humidity ratio. If the actual outdoor humidity ratio is lower than the calculated humidity ratio limit and there is cooling load, then the outdoor airflow rate is increased. 6 - Fixed Dew Point and Dry Bulb - The HVAC system will compare both the outdoor dewpoint temperature and the outdoor dry-bulb temperature to their specified high limit values (default of 28C). The outdoor air flow rate will be increased when there is cooling load and the outdoor air is below both thresholds. 7 - Differential Dry Bulb And Enthalpy - The HVAC system will increase the outdoor air flow rate when there is a cooling load and the outdoor air temperature is below a specified dry bulb temperature limit (default is 28C) AND enthalpy below a specified enthalpy limit (default is 64000 J/kg).sensibleHeatRecovery [Optional]
A number between 0 and 1 that sets the sensible heat recovery effectiveness of a heat recovery system on the HVAC (at approximately 75% of maximum flow rate). Typical values range from 0.45 (for a heat pipe or glycol loop system) to 0.81 (for an enthalpy wheel). If this value and the value below are set to 0, no heat recovery will be written into the model. The default varies based on HVAC type. Systems 1-10 (code baseline systems) do not have heat recovery by default. Any system with a Dedicated Outdoor Air System (DOAS) includes an enthalpy wheel by default.latentHeatRecovery [Optional]
A number between 0 and 1 that sets the latent heat recovery effectiveness of a heat recovery system on the HVAC (at approximately 75% of maximum flow rate). Typical values for an enthalpy wheel are around 0.73 and most other types of heat recovery are sensible-only, in which case this input will be 0. If this value and the value above are set to 0, no heat recovery will be written into the model. The default varies based on HVAC type. Systems 1-10 (code baseline systems) do not have heat recovery by default. Any system with a Dedicated Outdoor Air System (DOAS) includes an enthalpy wheel by default.
Outputs
airDetails
A description of the HVAC ventilation system (or system air side), which can be plugged into "Honeybee_HVAC Systems" component.