List of Variables

When creating a Design variable it is necessary to select a variable type. This topic summarises the variable types available for selection in the browse list.

Variables List

Natural ventilation/infiltration

• Natural ventilation rate - Used only when the Natural ventilation model option is set to Scheduled.
• Nat vent set-point temp - Requires a Natural ventilation system to have been included in the base model.
• Nat vent max temp difference - Requires a Natural ventilation system to have been included in the base model.

• Infiltration - Scheduled natural ventilation only. When this variable is applied infiltration is automatically activated in the optimisation simulations even if the Model infiltration model option is switched off in the base model.
• Airtightness - Value range between 0 and 4 to cover the 5 Airtightness slider settings when using Calculated natural ventilation. When this variable is applied infiltration is automatically activated in the optimisation simulations even if the Model infiltration model option is switched off in the base model.
• Crack template - Used only when the Natural ventilation model option is set to Calculated. When this variable is applied infiltration is automatically activated in the optimisation simulations even if the Model infiltration model option is switched off in the base model.
• % External window opens - Used only when the Natural ventilation model option is set to Calculated.

• % Roof window opens - Used only when the Natural ventilation model option is set to Calculated.
• Vent area - the area of the auto-generated external vents (does not affect custom drawn vents) - Used only when the Natural ventilation model option is set to Calculated.
• Internal vent area - the area of the auto-generated internal vents (does not affect custom drawn vents) - Used only when the Natural ventilation model option is set to Calculated.
• Roof vent area - the area of the auto-generated roof vents (does not affect custom drawn vents) - Used only when the Natural ventilation model option is set to Calculated.

• Mixed mode switch off when raining - When this variable is applied the Mixed mode natural ventilation option is automatically activated in the optimisation simulations even if the Mixed Mode Zone Equipment > Mixed mode on model option is switched off in the base model. Note however that the Natural Ventilation > On model option must still be manually set in the base model for mixed mode setting to be applied in the simulation.
• Mixed mode max wind speed - When this variable is applied the Mixed mode natural ventilation option is automatically activated in the optimisation simulations even if the Mixed Mode Zone Equipment > Mixed mode on model option is switched off in the base model. Note however that the Natural Ventilation > On model option must still be manually set in the base model for mixed mode setting to be applied in the simulation.
• Mixed mode min temperature - When this variable is applied the Mixed mode natural ventilation option is automatically activated in the optimisation simulations even if the Mixed Mode Zone Equipment > Mixed mode on model option is switched off in the base model. Note however that the Natural Ventilation > On model option must still be manually set in the base model for mixed mode setting to be applied in the simulation.
• Mixed mode max temperature - When this variable is applied the Mixed mode natural ventilation option is automatically activated in the optimisation simulations even if the Mixed Mode Zone Equipment > Mixed mode on model option is switched off in the base model. Note however that the Natural Ventilation > On model option must still be manually set in the base model for mixed mode setting to be applied in the simulation.
• Mixed mode min enthalpy - When this variable is applied the Mixed mode natural ventilation option is automatically activated in the optimisation simulations even if the Mixed Mode Zone Equipment > Mixed mode on model option is switched off in the base model. Note however that the Natural Ventilation > On model option must still be manually set in the base model for mixed mode setting to be applied in the simulation.
• Mixed mode max enthalpy - When this variable is applied the Mixed mode natural ventilation option is automatically activated in the optimisation simulations even if the Mixed Mode Zone Equipment > Mixed mode on model option is switched off in the base model. Note however that the Natural Ventilation > On model option must still be manually set in the base model for mixed mode setting to be applied in the simulation.
• Mixed mode min dew point temperature - When this variable is applied the Mixed mode natural ventilation option is automatically activated in the optimisation simulations even if the Mixed Mode Zone Equipment > Mixed mode on model option is switched off in the base model. Note however that the Natural Ventilation > On model option must still be manually set in the base model for mixed mode setting to be applied in the simulation.
• Mixed mode max dew point temperature - When this variable is applied the Mixed mode natural ventilation option is automatically activated in the optimisation simulations even if the Mixed Mode Zone Equipment > Mixed mode on model option is switched off in the base model. Note however that the Natural Ventilation > On model option must still be manually set in the base model for mixed mode setting to be applied in the simulation.
• Nat vent indoor min temp schedule -

• External window operation schedule - Used only when the Natural ventilation model option is set to Calculated.
• Internal window operation schedule - Used only when the Natural ventilation model option is set to Calculated.
• Roof window operation schedule - Used only when the Natural ventilation model option is set to Calculated.
• Earth tube ventilation rate - When this variable is applied the earthtube option is automatically activated in the optimisation simulations even if the Earth Tube > Include earthtube option is switched off in the base model.

• Limit value of opening nat vent modulation factor -
• Nat vent modulation lower value of Tin-Tout -
• Nat vent modulation upper value of Tin-Tout -

Glazing/shading

• Glazing template - Select a list of glazing templates to be evaluated. As each is template is assessed its data is loaded to the model.
• Glazing type - Select a list of glazing components to be evaluated.
• Facade type - Select a list of façade types to be evaluated.
• Window to wall % -
• Window frame type -
• Window blind type - When this variable is applied window blinds on external walls are automatically activated in the optimisation simulations even if the Window shading model option is switched off in the base model.
• Window shading control schedule - When this variable is applied window blinds on external walls are automatically activated in the optimisation simulations even if the Window shading model option is switched off in the base model.
• Local shading type - When this variable is applied local shading on external walls are automatically activated in the optimisation simulations even if the Local shading model option is switched off in the base model.

• Internal glazing type -
• Internal facade type - Select a list of façade types to be evaluated.
• % Internal glazing -
• Internal window frame type -
• % Internal window opens -
• Roof glazing type -
• Roof facade type -
• Roof window frame type -
• Roof shading coefficient -
• Roof window blind type - When this variable is applied window blinds on roof surfaces are automatically activated in the optimisation simulations even if the Roof Window shading model option is switched off in the base model.

• Roof window shading control schedule - When this variable is applied window blinds on roof surfaces are automatically activated in the optimisation simulations even if the Roof Window shading model option is switched off in the base model.

Activity/occupancy/comfort setpoints

• Activity template - Select a list of activity templates to be evaluated. As each is template is assessed its data is loaded to the model.
• Occupancy density -
• Occupancy (Days/week) -
• Heating set-point temperature -
• Heating set-back temperature - Note that heating setback temperatures only apply when the Heating operation schedule includes values of 0.5 to indicate times of setback operation.
• Cooling set-point temperature
• Cooling set-back temperature - Note that heating setback temperatures only apply when the Cooling operation schedule includes values of 0.5 to indicate times of setback operation.
• Heating set-point PMV - Only applies when using the 4-Fanger comfort option for the Temperature control option for a Detailed HVAC simulation.
• Heating set-back PMV - Only applies when using the 4-Fanger comfort option for the Temperature control option for a Detailed HVAC simulation.
• Cooling set-point PMV - Only applies when using the 4-Fanger comfort option for the Temperature control option for a Detailed HVAC simulation.
• Cooling set-back PMV - Only applies when using the 4-Fanger comfort option for the Temperature control option for a Detailed HVAC simulation.

• Mech vent set-point temp -
• Mech vent max temp difference -

• Mech vent rate per person -
• Mech vent rate per area -

Constructions

• Construction template - Select a list of construction templates to be evaluated. As each is template is assessed its data is loaded to the model. This option only applies when the (default) General construction and glazing data model option is set.
• Insulation - Like the Construction template variable above but with a limited set of options based on the "Early Design" Constructions templates and intended for use together with the Thermal mass variable described below. This variable only applies when the Pre-design construction and glazing data model option is set. The variable is numeric and parametric values are mapped as follows: 0=Uninsulated, 1=Typical ref, 2=Energy code, 3=Best practice. You should normally accept the default range 0-3. You can read about how the Pre-design construction templates are set up and controlled on the Legislative Region Templates - Standard Insulation help page.
• Thermal mass - See above for the Insulation variable. This variable only applies when the Pre-design construction and glazing data model option is set. The variable is numeric and parametric values are mapped as follows: 0=Light, 1=Medium, 2=Heavy. You should normally accept the default range 0-2.
• External wall construction - Select a list of external wall constructions.
• Flat roof construction - Select a list of flat roof constructions.
• Pitched roof construction (occ) -
• Pitched roof construction (unocc) -
• Semi-exposed ceiling construction - Select a list of semi-exposed ceiling constructions between occupied and semi-exterior unconditioned zones above (e.g. ceilings between occupied zones and roofspaces).
• Semi-exposed floor construction - Select a list of semi-exposed floor constructions between occupied and semi-exterior unconditioned zones below (e.g. floors between occupied zones and basements).
• Ground floor construction - Select a list of ground floor constructions.
• External floor construction - Select a list of external floor constructions.
• Internal floor construction - Select a list of internal floor constructions.
• Wall sub-surface construction -
• Partition sub-surface construction -
• Roof sub-surface construction -
• External door construction -
• Internal door construction -
• Internal thermal mass construction - Select a list of Internal thermal mass constructions to be tested. This is the Construction used for hanging partitions and when a non-zero value has been entered for the zone internal thermal mass exposed area on the Constructions tab under the Internal Thermal Mass header.
• Component block material -

• Wall below grade construction -
• Partition construction -

• Basement ground floor construction -

Internal gains/lighting

• Lighting template - Select a list of lighting templates to be evaluated. As each is template is assessed its data is loaded to the model.

• Computer power density - Used only when the Equipment gain units model option is set to 1-Power density. When this variable is applied computer gains are automatically activated in the optimisation simulations even if the Computer > On model option is switched off in the base model.
• Equipment power density - Used only when the Equipment gain units model option is set to 1-Power density. When this variable is applied Office equipment gains are automatically activated in the optimisation simulations even if the Office Equipment > On model option is switched off in the base model.
• Miscellaneous power density - Used only when the Equipment gain units model option is set to 1-Power density. When this variable is applied Miscellaneous gains are automatically activated in the optimisation simulations even if the Miscellaneous > On model option is switched off in the base model.
• Catering power density - Used only when the Equipment gain units model option is set to 1-Power density. When this variable is applied Catering gains are automatically activated in the optimisation simulations even if the Catering > On model option is switched off in the base model.
• Process power density - Used only when the Equipment gain units model option is set to 1-Power density. When this variable is applied Process gains are automatically activated in the optimisation simulations even if the Process > On model option is switched off in the base model.
• General lighting power density - Used only when the Lighting gain units model option is set to 1-Power density. When this variable is applied general lighting gains are automatically activated in the optimisation simulations even if the General Lighting > On model option is switched off in the base model.
• General lighting normalised power density - Used only when the Lighting gain units model option is set to 2-Normalised Power density. When this variable is applied general lighting gains are automatically activated in the optimisation simulations even if the General Lighting > On model option is switched off in the base model.
• Task lighting power density - When this variable is applied task lighting gains are automatically activated in the optimisation simulations even if the Task and Display Lighting > On model option is switched off in the base model.
• External lighting -

• All gains - Used only when the Gains data model option is set to Lumped.

HVAC systems

• Simple HVAC template (Simple HVAC) - Select a list of HVAC templates to be evaluated. As each is template is assessed its data is loaded to the model. This option applies only when using the Simple HVAC model option.
• HVAC template (Detailed HVAC) - Select a list of Detailed HVAC templates to be evaluated. As each is template is assessed its data is loaded to the model. This option applies only when using the Detailed HVAC model option. Note that Detailed HVAC templates only support templates with a single HVAC zone group. The way that zones are allocated to the zone group is as follows. If the building is the target then all zones that don't use the <None> Simple HVAC template are included in the HVAC zone. Otherwise if individual zones are set as targets then only those zones are loaded to the HVAC zone group. In this case zones that are not included as targets will not be assigned an HVAC system and so will be unconditioned.
• Mechanical ventilation rate -
• Auxiliary energy - Simple HVAC only
• Pump etc energy - Simple HVAC only
• Heating system seasonal CoP - Simple HVAC only
• Cooling system seasonal CoP - Simple HVAC only

• Heating operation schedule -
• Cooling operation schedule -

Location/weather/orientation

• Location template - Select a list of Location templates to be evaluated. As each is template is assessed its data is loaded to the model at site level.
• Hourly weather data - Select a list of Hourly weather data to be evaluated. As each is Hourly weather component is assessed its data is loaded to the model at site level.
• Site orientation - adjusts the orientation of all objects on the site. See also Building rotation in the Other category.

Renewables

• Load centre 1 - the load centre variables can be useful for varying the number of PV panels in a study. Set up and select a number of load centres each one having a different number of PV panels.
• Load centre 2 - see Load centre 1
• Load centre 3 - see Load centre 1
• Load centre 4 - see Load centre 1
• Load centre 5 - see Load centre 1

Other

• Building rotation - adjusts the orientation of the building relative to the site. Building objects are rotated about the geometric centre point of all building objects. Care should be taken to ensure that building objects would not intersect with any site objects for all possible building rotations. Note that component blocks that are part of the wider site are not rotated with the building, but component blocks that are part of the building are. See under the help for Level setting under Component block settings. See also Site orientation in the Location/weather/orientation category.
• Zone capacitance multiplier -

Custom EMS

• Custom EMS - a special variable type which acts on EMS variables within EMS scripts. For example a line of EMS script such as:
  
  

SET HeatingSetpoint = <Var,SPTemp,20>,

could be written to indicate that HeatSetpoint can vary and if a Custom EMS variable with Variable key of SPTemp was included in the optimisation, then for each iteration of the simulation, the code in angle brackets would be automatically replaced, behind the scenes, with the setpoint temperature currently being tested, e.g.

SET HeatingSetpoint = 20.7,

The process involved in setting up Custom EMS variables is explained in detail in the Advanced Tutorial - Custom EMS Variable

Custom IDF

• Custom IDF - a special variable type which adds a parametric variation to IDF files through an Output:PreprocessorMessage statement. This statement can be processed using CS-Script code together with the EpNet library for example.
  
  Extra IDF is added to main IDF in the form:
  

  Output:PreprocessorMessage,
  

  EpNet Script,

  Information,

  Variable key,

  CurrentValue;

  Where Variable key is the setting made on the dialog, matching up with corresponding code in the scripts and CurrentValue would be automatically replaced with the value of the variable for the current iteration.

  Important Note: You must write extra script to pre-process the IDF Output:PreprocessorMessage IDF statement to ensure that variables of type Custom IDF have an effect on the simulations. This might typically be done in the BeforeEnergySimulation callback script which can be used to process the Output:PreprocessorMessage IDF data generated by the Custom IDF variable and insert the setting for the CurrentValue for each simulation.

Custom Script

• Custom Script - where you can write a script which applies changes to the model via the DesignBuilder API in response to the variable value passed in. A hook function is called in all active CS-Scripts and plugins to allow your to define your own custom variants of the model based on current variable values. This is an extremely flexible way to set up design variables as it allows you to control the exact impact on the model of each variable change.

The process involved in setting up Custom Script variables is explained in detail in the Custom Script Variable Tutorial.

Tip: The Extensibility Tools User Guide is the main source of help for scripts and the API.