Using this section requires choosing a workspace and installing the Sample Library. See Setting up Vulcan Software for instructions. Batch modelling, particularly with customised parameters or merges, can produce unexpected outputs, so users are responsible for checking the inputs and results.
Structure of the Scenarios Section
The Scenarios section runs local Home Energy Model simulations outside the ECaaS compliance submission workflow. Use Calculate for ECaaS compliance drafts and submissions.
Use it to:
- use alternative data for weather, occupancy, fabric, and systems than what is automatically set by FHS or other wrappers. This can be useful to calibrate models to actual or potential dwelling use
- understand detailed half-hourly outputs, including heat balance and heating/cooling system data
- test the impact of design changes on outputs without creating new input files
Defining Batch Configs and Scenarios
Batch simulation configurations (Batch Configs) are created and edited in the Scenarios section, and saved into the user's workspace under input/batch_configs.
All Batch Configs must have a Base input file created from the Geometry section, as well as a wrapper. Additional parameters can be chosen from the categories outlined below.
If multiple parameters are chosen for a single category within a single scenario, each selected parameter is modelled as a separate permutation. This approach would be used, for example, if modelling a single dwelling with two separate weather files. Alternatively, separate scenarios can be used. The total number of permutations modelled is visible at the top of the page.
Before running a Batch Config, check that:
- the workspace is selected and the Sample Library is installed or restored
- the Geometry model has been saved successfully
- the saved geometry has built a merged HEM input in
input/batch_parameters/base_json - the required base input is selected
- a model wrapper and weather input are selected
- any FHS-validated base input uses an FHS wrapper, such as
fhs_assumptionsorfhs_compliance - any visible validation messages in the Scenarios section have been resolved or understood
Batch Parameters
Batch Configs are built from parameter categories. The app groups common public-facing parameter categories into core inputs, fabric, and systems. Other advanced or custom categories may appear depending on the installed library and selected wrapper.
Core Inputs
Base input file: The dwelling input created from the Geometry section. Each Batch Config needs at least one base input.
Model wrappers: Choose how the model should run. fhs_compliance creates detailed FHS outputs, fhs_assumptions applies FHS assumptions while preserving a core-style run, and passthrough runs the model without a compliance wrapper. If the base input was created for FHS validation, use an FHS wrapper rather than passthrough.
Weather files: Choose the weather file used for the simulation. Weather files are the Scenarios weather input. ECaaS uses the compliance weather file for compliance calculations.
Location: Sets location-related conditions for infiltration and ventilation, such as exposure, terrain, ventilation zone height, and altitude.
SAP XML: Toggles creation of a SAP10 XML file in the outputs.
Additional outputs: Toggles optional post-processing outputs, such as heat balance and detailed heating/cooling files.
Compliance settings: Varies inputs used for HEM:FHS runs, such as Part O/G settings, bedroom and wet room counts, ground floor area, and heating control type.
Fabric
Simplified fabric: Varies thermal properties for windows, walls, roofs, doors, party elements, ground floors, and thermal bridges.
Airtightness: Varies airtightness test pressure and test result.
Glazing: Varies the amount of glazing on external walls within selected orientations.
Orientation: Rotates building elements to test different dwelling orientations.
Systems
Heat source: Varies wet heat sources such as heat pumps, boilers, heat batteries, or immersion heaters.
Hot water source: Varies the hot water system, such as a combi boiler, cylinder, heat pump cylinder, or immersion heated cylinder.
Hot water demand: Varies hot water use assumptions.
Events: Sets hot water event patterns, such as repeated draw-offs over a day, week, or year.
Space heat emitters: Creates or replaces emitters for a space heating system, such as radiators or underfloor heating.
Space heat systems: Creates or replaces the wider space heating system linked to the heat source and emitters.
Space cooling systems: Creates or replaces space cooling systems.
Mechanical ventilation unit: Creates or replaces the mechanical ventilation unit.
Lighting: Creates or replaces lighting assumptions, including zone-specific lighting where relevant.
Solar systems: Creates or replaces solar PV assumptions.
Battery systems: Creates or replaces battery assumptions.
Tariffs are managed in the Results section for cost metrics, rather than selected as a Scenarios category.
Parameter Library, custom snippets, and JSON editing
The parameter list is loaded from input/batch_parameters in your workspace. Snippets listed in the Sample Library manifest are shown as Library snippets. Files that are present in the workspace but are not part of the manifest are shown as Custom snippets.
The parameter rows include a JSON view button so you can inspect the file that will be merged into the model. Most parameters can be duplicated to create an editable copy, but weather files and model wrappers are not duplicated from this control. Parameters that are not part of the initial sample library can also be edited.
Schema validation is provided for editing the base JSON and some other parameters, but this should be treated as indicative for custom merge categories. If you create or edit custom snippets, review the generated inputs and outputs before relying on the scenario results.
Some categories can be assigned to detected zones when the UI shows zone assignment controls. For example, fabric, lighting, and heating distribution categories can be varied by zone where supported. If no zones are detected, save the base model from Geometry and refresh the Scenarios section before using zone-specific selections.
Running Batch Simulations
Saved Batch Configs appear in the Simulations Panel.
Batch Configs can be selected with a click. When Run Simulation is clicked, Configs are queued for local simulation. Simulation progress is visible through a loading bar. Simulations that do not have any associated output files are shown as To do. Simulations currently running are shown as Running. Simulations that produce all expected output files are shown as Complete. Simulations that either have an error or only partially produce expected files are shown as Error.
Very large scenario grids are highlighted above 500 permutations. If this happens, consider splitting the work into smaller Batch Configs or reducing the number of selected parameters before running.