This page explains the terms and abbreviations used in the Vulcan documentation. Where a guide explains a term in more detail, the entry links to it.
ABBE: Awarding Body for the Built Environment.
Areal heat capacity: The heat that a building element stores for each square metre of its area and each kelvin of temperature change, in J/(m²·K). See the Fabric Calculators Reference.
As-Built: The assessment stage for a dwelling as it was built. The other stage is Design. The stage changes the evidence that Vulcan expects. See Status and metadata.
Batch Config: A saved Scenarios configuration. It contains one or more base models, a model wrapper, and the parameters for each scenario. See Defining Batch Configs and Scenarios.
Base model: The complete HEM input file that Vulcan creates when you save a geometry file. Vulcan merges the geometry with the defaults file. Scenarios calls it the Base input file.
BREL: Building Regulations England Part L. The BREL report shows compliance with Part L of the Building Regulations in England.
DEA: Domestic Energy Assessor.
Defaults file: A HEM JSON file that gives the inputs that a geometry file does not set, such as schedules and default system values. Each HEM model version has a fixed defaults file. See Defaults tab.
DESNZ: Department of Energy Security and Net Zero.
EASOB: Energy Assessor Scheme Operating Board.
ECaaS: Energy-Calculations-as-a-Service. The official HEM calculation service for compliance submissions. See the Calculate Section Guide.
ECaaS-only product: A product, such as a PCDB heat pump, that ECaaS can calculate but Vulcan cannot run locally. Submit a model that uses one from Calculate. See Where system values come from.
EPC: Energy Performance Certificate.
FEE: Fabric Energy Efficiency. The space heating and cooling demand of the dwelling, which depends mainly on its fabric. The fhs_compliance wrapper calculates it. See FHS Compliance.
FHS: Future Homes Standard. The energy standard for new homes in England, set by the 2026 editions of Approved Documents L and F. See HEM:FHS timelines.
HEM: Home Energy Model. The government calculation method for the energy performance of homes.
HEM model version: The HEM engine and FHS wrapper version that Vulcan uses to prepare and calculate a model, for example Rust HEM:FHS 1.0.0a7. Set it in Geometry Global Settings. Versions other than the default need Vulcan Pro. See HEM model version.
HTC: Heat transfer coefficient. The rate of heat loss from the dwelling for each kelvin of difference between inside and outside temperature, in W/K.
IFC: Industry Foundation Classes. A file format that CAD tools use to exchange building models. Vulcan imports IFC4 files. See Files dropdown.
Internal QA: A submission purpose that only Vulcan reviewers can use. See Service and membership status.
Linear thermal bridge: A line where two building elements meet, such as a wall and a floor, that loses more heat than the elements around it. Its heat loss is given by its length and its ψ (psi) value, in W/(m·K). In Vulcan, it is the Linear bridge element. See Thermal bridge proposer and validation.
Live Project: A submission purpose for a real assessment. Active Vulcan Scheme Members can use it, and it uses one lodgement credit. See Service and membership status.
Lodgement: The app's name for a submission that Vulcan prepares for ECaaS in the Calculate section.
MCP: Model Context Protocol. An open standard that connects AI applications to other tools. See the Vulcan MCP Server Guide.
MEV: Mechanical extract ventilation. Fans remove air from wet rooms, and no heat is recovered. See Ventilation: MEV or MVHR.
MHCLG: Ministry of Housing, Communities and Local Government. Formerly DLUHC or CLG.
MVHR: Mechanical ventilation with heat recovery. One unit supplies and extracts air, and recovers heat from the extracted air. See Ventilation: MEV or MVHR.
Notional dwelling: A reference version of the dwelling with standard fabric and services. FHS compliance compares the actual dwelling with it. See FHS Compliance.
OCDEA: On Construction Domestic Energy Assessor.
Part F: The part of the Building Regulations for ventilation. Vulcan checks the ventilation in a model against it. See Rules Vulcan checks.
Part G: The part of the Building Regulations for sanitation and hot water, including water efficiency.
Part O: The part of the Building Regulations for overheating in new homes.
PCDB: Product Characteristics Database. The database of tested heating, hot water, and ventilation products. See Where system values come from.
Point thermal bridge: A single point that loses more heat than the elements around it. Its heat loss is given in W/K. In Vulcan, it is the Point bridge element.
PV: Photovoltaic. Solar panels that generate electricity.
Qualification: A submission purpose for qualification assessments. Active Vulcan Scheme Members can use it, and it uses one lodgement credit. See Service and membership status.
Quick sim: A preview calculation of the saved model in the Geometry section. It shows headline results, such as the FHS primary energy rate. See Quick sim.
Sample Parameter Library: The example and reference files that Vulcan installs in your workspace, including the defaults file, scenario snippets, example models, and tariffs. See Sample Parameter Library.
SAP: Standard Assessment Procedure. The government method for rating the energy performance of homes. SAP 10.2 and SAP 10.3 are still in use alongside HEM. For new homes in England, SAP 10.3 is currently the approved method for the Future Homes Standard; see HEM:FHS timelines.
Snippet: A parameter file in input/batch_parameters that a scenario merges into the model, for example a heat source or a weather file. See Parameter Library, custom snippets, and JSON editing.
SORs: Scheme Operating Requirements.
Space Labeller: The Geometry tool that marks room and space footprints in a zone. Vulcan uses the labels to set room counts and the living area. See Zone editor.
Training: A submission purpose that every user can use. Training submissions are free. See Service and membership status.
U-value: The rate of heat loss through one square metre of a building element for each kelvin of temperature difference, in W/(m²·K). A lower value means less heat loss. See the Fabric Calculators Reference.
Wrapper (model wrapper): The setting that chooses how HEM runs a model. fhs_compliance runs the full FHS compliance calculation, and fhs_assumptions runs one calculation with FHS assumptions. See Core Inputs.
WWHRS: Waste water heat recovery system. It recovers heat from shower or bath waste water to preheat cold water. See WWHRS, cooling, solar panels, and batteries.