From BIM geometry to simulation-ready analytical models
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SAM (Sustainable Analytical Model) is an open-source .NET toolkit that turns Revit and Rhino/Grasshopper geometry into reusable analytical building models — validated, attributed, and simulated with Tas as the primary engine, with psychrometric HVAC design workflows alongside.
SAM is a modular, open-source .NET/C# toolkit for creating, cleaning, enriching, exchanging, and simulating analytical building models — the watertight panels, spaces, and adjacency data that energy and HVAC simulation needs. One shared JSON analytical model carries the project from BIM geometry to results, so information is reused instead of rebuilt for every study.
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BIM to BEM
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Generate analytical panels, spaces, shells, and adjacency clusters from Revit, Rhino, and Grasshopper workflows.
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Simulation Ready
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Attribute constructions, profiles, internal conditions, openings, and systems before connecting to Tas and results workflows.
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Reusable Research Platform
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Use JSON-based analytical objects, validation routines, and extension modules to test repeatable methods across projects and papers.
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Core Analytical Concepts
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Geometry
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Planar geometry, faces, shells, apertures, and boundary representations used to derive simulation-ready spaces.
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Panels
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Walls, floors, roofs, apertures, constructions, and thermal properties represented as analytical objects.
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Adjacency Cluster
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The relationship layer for spaces, zones, panels, and their spatial/topological connections.
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Analytical Model
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The project container for geometry, location, profiles, materials, internal conditions, systems, and results.
From BIM geometry to auditable engineering workflows
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SAM is an open-source computational-engineering platform built around a shared analytical building model. It connects BIM, building physics, HVAC systems and simulation through reusable, traceable workflows.
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+ The SAM analytical model in the SAM Analytical desktop app: engineering data reviewed directly on the model, here ventilation requirements beside design airflows. F Part F requirement D design airflowFull size
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- Workflow
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How SAM Works
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Project inputs become one SAM analytical model, then move through validation, attribution, simulation, and HVAC comparison in a repeatable workflow.
Design tools feed a shared analytical building model. Engineering logic, systems and simulation all work on that model, and their results return to it.
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- SAM Analytical Model
- Panels, spaces, apertures, adjacency clusters, location, profiles, and libraries.
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- Validation + Attribution
- Watertight shells, cleaned geometry, constructions, loads, schedules, and system intent.
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- Simulation + Results
- Tas dynamic simulation, HVAC scenarios, result extraction, and post-processing.
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- Capabilities
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Capabilities Today
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Every capability links to the public repository that implements it. Status chips distinguish what is shipped from what is in active development — nothing in development is presented as finished.
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- Shipped
- In development
- Roadmap
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Hosts & exchange
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RevitRhinoGrasshopperIFCgbXMLLadybug ToolsBHoM
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Shared core
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SAM analytical modelSpaces, panels, apertures, adjacency, constructions, profiles, internal conditions, systems and results — one open JSON model, reused rather than rebuilt.
Results on the modelPlan overlaysAssessmentsReportsExcel & SQLite
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Grasshopper is one host for SAM, not SAM itself. Tas is one simulation integration, not SAM itself.
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Shipped and in daily use
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BIM hosts: Revit & Rhino
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Analytical-model generation in Revit 2020–2026 (SAM add-in and Rhino.Inside.Revit) and in Rhino 8/9 with a large Grasshopper component library. SAM_Revit · SAM_Rhino_UI
- Shipped
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Tas simulation & HVAC scenarios
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Primary engine pathway: Tas TBD/TSD/T3D/TPD model exchange, overheating and compliance-oriented workflows (TM52, TM59, Part L), and reusable plant-room (EnergyCentre) templates for automated HVAC scenario comparison. SAM_Tas · SAM_Systems
- Shipped
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Psychrometrics & Mollier HVAC design
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Moist-air calculations, Mollier chart plotting, air-process loads, and concept-stage HVAC exploration — numerically validated against published reference data (ASHRAE, PsychroLib, IAPWS). SAM_Mollier · SAM_Validation
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Model exchange
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IFC, gbXML, IES VE GEM, BHoM, and Excel import/export, plus bidirectional Honeybee schema 2.6 round-trip exchange for Ladybug Tools workflows. SAM_IFC · SAM_gbXML · SAM_LadybugTools
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Desktop applications
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Four Windows desktop apps — SAM Analytical, SAM Analytical Mollier, SAM Geometry, and SAM Weather — for model inspection, psychrometric design, geometry work, and weather data. SAM_UI
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One analytical model core
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Panels, spaces, apertures, adjacency clusters, profiles, materials, internal conditions, and systems in a single JSON model, scriptable from Grasshopper. SAM
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In active development (2026)
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SAM_OCCT — native watertight geometry
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An Open Cascade geometry kernel inside SAM: sewing and healing of open shells into watertight solids, booleans, STEP/IGES exchange, cell complexes, and a 3D solver — with tests and CI, not yet wired into the SAM core model. SAM_OCCT
- In development
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Native OpenStudio conversion
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Direct SAM-to-OpenStudio model generation: geometry, constructions, schedules, and thermostats with ideal-air loads (airside and plant HVAC not yet covered). OpenStudio remains a secondary, EnergyPlus-oriented pathway alongside Tas. SAM_OpenStudio
- In development
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SharpDX 3D viewport
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A new GPU-accelerated viewport for the desktop apps, replacing HelixToolkit, with undo/redo support across the interface. SAM_UI
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Systems ↔ Mollier plant-room bridge
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Connecting SAM_Systems plant-room schematics with Mollier psychrometric processes for air-handling and plant design workflows. SAM_Systems
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What makes it different
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One model, many workflowsGeometry, constructions, systems and results live in one analytical model that every workflow reads and extends.
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Explicit engineering dataSpaces, adjacency, systems and their relationships are named, inspectable objects — not hidden tool state.
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Deterministic and auditableWorkflows are repeatable and record what they used, so results can be reviewed and reproduced.
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BIM and simulation connectedAuthoring tools and simulation engines are adapters around the model, not separate islands of data.
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Decisions keep their authorityRegulatory requirements, engineering design and equipment capability stay distinct. See the principle
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Open, scriptable, extensibleLGPL-licensed .NET code, scriptable from Grasshopper and C#, extended through independent modules.
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SAM supports engineering workflows that contribute to assessment methods. Compliance still depends on the complete project methodology and toolchain.
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- Roadmap
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Research-Backed Maturity
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Platform stages follow the published research line. SAM 4.0 and 5.0 are future directions; SAM_Mollier develops in parallel as a module, not a platform version.
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- SAM 1.0
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Geometry creation, multi-method model generation, adjacency clusters, shell creation, and watertight boundary preparation. Shipped
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- SAM 2.0
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Loads, attribution, material/profile/internal-condition libraries, dynamic simulation connectors, and BIM-to-BEM research validation. Shipped
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- SAM 3.0
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Reusable HVAC system generation, JSON system references, Tas EnergyCentre templates, automated scenario execution, and result extraction. Shipped
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- SAM_Mollier Parallel module
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Psychrometric points, Mollier and psychrometric charts, air processes, HVAC loads, and concept-stage system exploration.
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- SAM 4.0
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Controls and control-strategy testing for HVAC system operation and scenario analysis. Roadmap
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+ Capabilities
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What SAM does
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Six capability families, each built on the same analytical model and implemented in public repositories.
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- SAM 5.0
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Digital twin direction: an updatable building representation with geometry, systems, assumptions, results, and project data. Roadmap
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Analytical modelling
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Spaces, panels, apertures, adjacency, materials, constructions, profiles, internal conditions, systems and results in one model — inspected and edited in the SAM desktop apps.
Analytical models from Revit 2025–2027 and Rhino 8/9, with IFC, gbXML, IES VE GEM, BHoM and Ladybug Tools exchange. A watertight Open Cascade geometry kernel is in development.
Loads, ventilation, overheating and thermal-simulation workflows on the model, including Part F ventilation traced to Approved Document F and Part O overheating assessed with CIBSE TM59.
Building systems as explicit engineering networks: plant rooms, air handling and ventilation, catalogue equipment selection, and psychrometric air processes on the Mollier chart.
Repeatable, scriptable workflows: a large Grasshopper component library, .NET APIs, scenarios run in series or in parallel, and data exchange for large models.
SAM_ValidationNumerical validation against published reference data (ASHRAE, PsychroLib, IAPWS).
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+ Flagship workflow
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One example of SAM in practice: Part F to Part O
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A three-dwelling model taken from ventilation requirement to overheating result. The analytical model, engineering logic, equipment data and simulation work together; each image is a real SAM screen.
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Analytical model
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Regulatory requirement
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Engineering design
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Equipment decision
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Simulation
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Engineering result
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Geometry and solvers
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SAM_OCCTNative Open Cascade geometry: watertight sew-and-heal, booleans, STEP/IGES, 3D solver. In development
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SAM_TopologicTopological space and building representations.
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+ 01 Regulatory requirement
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Part F calculates what must be achieved.
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SAM derives the Approved Document F airflow for each room from the model and shows it on the plan beside the design.
+ Authority: Regulation
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+ E01Bedroom supply: Part F requires 63 l/s; the design holds 143 l/s. Two quantities on one plan.
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BIM and exchange
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SAM_RevitRevit and Rhino.Inside workflows (Revit 2020–2026).
Calculation proposes; the engineer reviews. Here design airflow is raised above the requirement to address overheating, while the requirement and the unit’s capacity stay unchanged.
+ Authority: Engineer
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+ E02The regulatory requirement, engineering design and selected equipment capacity remain separate decisions.
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Simulation and HVAC
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SAM_TasPrimary Tas EDSL simulation integration: TBD/TSD/T3D/TPD, TM52/TM59/Part L, plant-room templates.
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SAM_OpenStudioSecondary OpenStudio model generation and exchange; native conversion in development.
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SAM_LadybugToolsHoneybee schema round-trip and Ladybug Tools interoperability.
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SAM_SystemsBuilding systems, plant rooms, and HVAC system concepts.
Each dwelling gets the smallest catalogue unit that meets its design duty; the unit’s maximum is a ceiling, never a design value. SAM then builds a repeatable simulation scenario and records its state.
+ Authority: Product
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+ E03SAM materialises the engineering design into a deterministic simulation scenario and records the run state. Full size
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Engineering physics
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SAM_MollierMollier charts and psychrometric HVAC processes.
SAM_IAPWSWater and steam properties using IAPWS-IF97.
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+ 04 Simulation & result
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Tas simulates; SAM assesses the result.
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The building is simulated in Tas and each room assessed against CIBSE TM59. On 2050s design weather this case still fails in 6 of 8 rooms — and SAM says so.
+ Authority: Simulation
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+ E04Example TM59 assessment showing the recorded room-level outcome; SAM reports the result rather than forcing a pass. Full size
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On the 2026-Q3 release line, the same design can be simulated through inter-zone airflows or through explicit ventilation systems in Tas, including selected-product cooling, with the unchanged TM59 assessment. Technical record
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SAM supports engineering workflows that contribute to assessment methods; compliance depends on the complete project methodology. A TM59 pass is an overheating result, not a Part O compliance certificate.
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User layers and scripting
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SAM_UIWindows desktop apps: SAM Analytical, SAM Analytical Mollier, SAM Geometry, SAM Weather.
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SAM_Rhino_UIRhino plugin and command-based access.
Different engineering concepts stay different objects
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A requirement is not a design, and a design is not what equipment can deliver. SAM keeps each quantity as its own object with its own authority, so one value never silently becomes another. The flagship workflow shows it with airflow:
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Required
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The minimum the regulation demands.
+ Authority: Regulation
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Design
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What the engineer decides to ventilate at.
+ Authority: Engineer
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Selected capacity
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What the selected unit can deliver — a ceiling, not a target.
+ Authority: Product
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Operating
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What flows in the simulated or commissioned system.
The published installer is built and payload-checked in CI and was smoke-tested manually in Rhino, Grasshopper, the Revit add-in and Rhino.Inside.Revit. The wider clean-install, upgrade and uninstall acceptance matrix was not re-run for this build.
SAM is developed in the open and published through peer-reviewed building-simulation venues. Publications are listed with DOI or proceedings links where available; author profiles on ResearchGate carry the full list.
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Numerical quality: psychrometric and steam-property calculations are tested against published reference data — ASHRAE Fundamentals tables, PsychroLib, and IAPWS-IF97 — in the public SAM_Validation suite.
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Sustainable Analytical Model (SAM 3.0): A New Approach to Automated HVAC Simulation
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M. Dengusiak, J. Ziolkowski, M. Dengusiak. BSA 2026.
- SAM 3.0HVAC automationTas
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Presented at BSA 2026 (Bozen-Bolzano, June 2026); proceedings forthcoming.
Developed in the open; published at peer-reviewed building-simulation venues — from BIM-to-BEM model generation to psychrometrics and automated HVAC simulation.
+ Michal Dengusiak
+ Co-creator and engineering lead. Chartered Engineer; previously at Arup, Buro Happold and Hoare Lea. SAM-BIM is independent and not sponsored or endorsed by those organisations.
+ LinkedIn · ResearchGate
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