Mold Simulator and Frame Simulator 9
The items of the official release notes, grouped by topic and by program, each with an explanation of what changes in day-to-day work and, where useful, screenshots of version 9 in English.
Artificial intelligence and automation
The four features that cut down model preparation: materials, boundary conditions and the project template are set automatically, and an AI assistant can drive the program.
AI assistants can now drive the software through the built-in MCP server
Mold Simulator and Frame Simulator 9 include an MCP (Model Context Protocol) server, called Heatsim, which exposes the program’s commands to an AI assistant. With Claude Desktop, Claude Code, ChatGPT, Cursor, VS Code or Codex connected, the assistant reads the open project and can work in the software: import a DXF, assign materials and boundary conditions, generate a thermal bridge with the Bridge Generator, run the simulation, read the results and lay out a report.
You can ask what you would ask technical support: check the settings of a calculation and explain what to correct, or vary the insulation thickness until the mould risk disappears. The answers are based on the actual project and results, not on generic values.
The server is started with the Heatsim button at the bottom right of the view bar, which stays highlighted while it is running. The Connect an AI assistant window configures the client. To keep it always on, start the program with the -mcp option. The scripting plugin is not required.
Requirements. The MCP connection works with an active Updates & Upgrade subscription. The AI assistant (Claude, ChatGPT or other) is the user’s own service.
New automatic material fill of the section regions, with review of uncertain cases
The Auto fill button in the Areas tab classifies every closed region of the drawing and proposes the most likely material, using a model trained on real sections of windows and thermal bridges. Before starting you set:
- project type (for example window, or window + construction);
- whether the drawing contains adiabatic areas;
- frame system: wood, PVC, aluminium, wood-aluminium or auto;
- handling of the EN ISO 10077-2 insulation panel (for the Uf calculation);
- the confidence threshold below which the program asks for confirmation (80% by default) and the order of the libraries to search.
The result opens in a review table: first the uncertain regions, then those filled automatically, finally those left empty as cavities. For each region you see its size, the confidence and the proposed material. The magnifier zooms the view to the region, quick search finds another material, and the choice can be applied to all areas with the same name or colour. Undo and redo are available.
If you run the fill again on a project that is already filled, the existing materials are re-evaluated but kept as the proposed choice. Compared with version 8, there is no longer any need to give special names to the hatch layers of the DXF.
Good to know. Auto fill is a starting point: always check the result, especially spacers, sealants and thin gaps between frame parts. The material labels (Modelling section) let you do this in seconds.
Boundary conditions can now be assigned automatically with one click
The auto-assign button in the Boundary tab assigns the internal boundary condition to the faces on the warm side and the external one to the faces on the cold side, reading the heat flow direction and the temperatures of the boundary conditions set by the project template. It also recognises scenarios with a third environment: the ground under a floor, an unheated room in one corner of the section (it asks which one) and the window installation joint, where it assigns the internal window boundary to frame and glass.
Adiabatic cut and symmetry boundaries are never assigned automatically: if the section has none, the program says so and asks you to assign them by hand first. Check the result in the boundary view and correct it where needed; it works best when you start from the right project template.
Automatic template suggestion when importing a 2D DXF drawing
Up to version 8, importing a DXF correctly required choosing the right project template first, since it sets boundary conditions, heat flow direction and calculation standards. Now the program analyses the imported drawing, for example whether it contains a window or a part below ground, and suggests the matching project template. The user confirms it or picks another one.
Modelling and materials
Tools to check and assign materials faster.
Labels with the material name and leader lines for all filled areas, in 2D and 3D
A button in the view bar shows a label for every filled area, with the material name and conductivity, connected to the area by a leader line. The labels are stacked along the edges of the view, so they stay readable even for layers a few millimetres thick. You can show one label per area or one per material, and leave out the cavities.
They work in the areas, boundary and simulation views, in 2D and 3D. Use them to check at a glance what auto fill has assigned and to prepare clear pictures for your client.
Quick material search while typing the name in the materials panel
In the material library, type part of the name and the list is filtered as you type, without browsing folders and subfolders. The same search is available in the auto fill review table.
Calculation and results
Faster simulations, mesh control and more complete results for air cavities.
Much faster simulations
The largest gain is in 3D, where the work on meshing and calculation has cut computing times considerably and made simulations more stable (see also adaptive refinement in the Mold Simulator 3D section). In 2D, in the heaviest cases such as ISO 15099 cavities with radiosity, the program adds the necessary calculation passes by itself instead of refining the mesh further, giving shorter times for the same accuracy.
Maximum mesh segment length setting for 2D simulations
The advanced simulation settings have a new Max segment length parameter: the 2D mesh generator does not create edges longer than this value. It is useful in very large models, such as thermal bridges with the ground, where it gives an adequate mesh without greatly increasing the number of subdivision steps.
The default value (1 km) effectively disables it. For a ground model, 2000 mm is a reasonable starting value.
More accurate ISO 10211 C.2 flow error in simulations
Among the results the program reports the convergence error required by EN ISO 10211, Annex C.2 item d): the sum of the absolute values of the heat flows entering the model, calculated with n and with 2n nodes, shall not differ by more than 1%.
In version 9 this value is calculated more accurately in 2D simulations. If it stays above 1%, the program automatically runs additional simulation steps.
Detailed analysis table for each air cavity in the advanced results
For each detected cavity, the advanced results list the values used to calculate its equivalent conductivity: dimensions along and across the heat flow, mean temperature, radiative coefficient hr0 and resulting conductivity. The same values are available as report tags.
The table answers a request from users who have to document the cavity calculation to EN ISO 6946 or EN ISO 10077-2 for a certification body: the automatic calculation can now be checked by hand, cavity by cavity.
Reports
More custom data, complete legends and direct PDF output.
Add an unlimited number of custom project tags for reports
Free project tags used to be limited in number. Now you can create as many as you need (client, location, job number, revision, engineer in charge…) and use them in report labels, which update by themselves when the value changes.
Report views can now be exported directly to PDF from the print window
From the report print window, views are saved directly to a PDF file, without going through a virtual PDF printer installed in Windows.
Label background images are now embedded in the project and travel with the file
A label with a background image, such as the firm’s logo or letterhead, keeps a copy of the image inside it. When the project is opened, the program first looks for the file at its original path; if it cannot find it, it uses the embedded copy. A project opened on another computer, or sent to a colleague, therefore shows the complete report.
Glaser colour legend available as a report tag
The colour scale of the Glaser simulation, with the amount of condensation, can be placed in a report label next to the view, as already possible for temperatures and heat flows. Readers of the report see the order of magnitude of the value straight away.
Condensation and mould legend colours available as report tags
The colours of the surface condensation and mould isotherms are also available as tags, to build a report legend that explains the two curves.
Graphics, languages and privacy
Interface changes common to all programs.
New rendering engine for all views and reports
All views, on screen and in reports, use a new graphics engine. Pictures are sharper, and the program also works with less powerful integrated graphics cards and with some NVidia cards that had display problems with the previous engine.
Full support for English, Italian, Spanish, French and German
Interface, libraries of materials, boundary conditions, scenarios and reports, the manual and the scripting documentation are available in five languages. The language is changed in View › Program settings › Localization and applies from the next start. It is best set before starting a calculation, since project files and screenshots come out in the chosen language.
New Privacy tab for anonymous statistics and auto fill training data
In the program settings, the Privacy tab groups two choices:
- Send anonymous usage statistics: anonymous usage data, used for updates and support;
- Help improve automatic material fill: Ask me, Yes or No. With consent, after a review only the size and shape measurements of each region, the proposed material and the chosen material are sent. Coordinates, outlines, file names and any other project data never leave the computer.
Each installation has an anonymous ID. The choices can be changed at any time.
Startup no longer hangs when the usage statistics server is slow or unreachable
On company networks with firewalls or proxies, or with a missing or slow connection, sending the statistics at startup could slow down or block the program from opening. Now the program starts anyway, without waiting for the server to answer.
Bridge Generator
Mold Simulator’s parametric thermal bridge generator reaches 624 variants, with new junctions and a picture-based template choice.
Choose the thermal bridge by clicking its junction on a schematic building
In File › New, Thermal bridges tab, a schematic building opens with the junctions marked by a code:
Clicking a junction starts a picture-based wizard, with questions such as Where is the window?, which leads to the right Bridge Generator template. If you prefer the list of templates, untick Show building.
New schematic previews for all project templates and the thermal bridge wizard
Project templates and wizard pages have new, simple and consistent previews. The edge colours show the environments: red internal, blue external, green unheated room.
The thermal bridge generator can now model a wall with a pitched roof
New wall–pitched roof junction, in three templates: pitched roof over a heated room, with an unheated attic above the ceiling, or with an unheated room below. For each one you choose the insulation position in the wall and in the roof (none, external, middle, internal), the presence of the structural node (ring beam) and its correction: 48 variants per template, all parametric.
New thermal bridge templates for a wall between rooms, with and without an unheated room
The junction between the external wall and an internal wall separating two rooms, in two templates: both rooms heated (two environments) or one of them unheated, such as a stairwell or a garage (three environments). The variants cover the insulation positions and the ring beam with and without correction.
Window installation thermal bridges according to UNI 11979 Annex E (reveal and sill)
The Italian standard UNI 11979:2025 requires the linear thermal transmittance Ψ of the installation joints of subframes and monoblock subframes, calculated on the standardised build-ups of its Annex E. The Bridge Generator contains all of them, ready to use:
- reveal, joints E.1–E.16: subframe or monoblock subframe, installed at the internal edge or mid-wall, in monolithic block masonry, with external insulation, cavity wall or CLT construction with external insulation;
- sill, joints E.17a and E.17b.
In the opening you can use the special element defined by the standard or a real frame and glazing, as in the existing window joint template. Every joint stays parametric: dimensions, wall build-up, sealing, reveal adhesive, subframe, sill, mortar bedding and sill insulation are edited from the bridge parameters.
The thermal bridge generator can now model a room over an underground garage, with the ground
This is a frequent question from users: the wall–floor junction above a garage or an underground cellar, with the ground against the lower wall. In the wall–floor junctions you switch on the ground option and set its width (3 m by default), level, material, bottom boundary (adiabatic, or ISO 13788 ground for the mould check) and the floor-on-ground resistance, if known.
- If the room below is unheated, the ground is geometry only and Ψ and mould are calculated as before.
- If it is heated, the buried wall becomes a wall against ground and its transmittance Uwb is calculated by the program according to EN ISO 13370, from the ground conductivity, the buried depth and the wall layers.
Mold Simulator 3D
Faster, more stable calculation, more robust import and automatic checks on cavities.
Stable adaptive refinement even on thin details
Adaptive refinement of the 3D mesh stays stable even with elements that are very thin compared with their length, such as sheet metal, brackets, metal profiles and membranes, which previously could require splitting the volumes by hand. Together with the calculation optimisations, this is the main reason for the much faster 3D simulations.
Floor-on-ground thermal bridges can now also be generated as a 3D wall corner
In the Bridge Generator floor-on-ground templates you can also generate the three-dimensional wall corner: the program builds the 3D model of the corner on the ground, calculates the point thermal transmittance χ and checks the mould risk in the corner, which is the most critical point of the junction.
Automatic detection of open unventilated and slightly ventilated cavities in 3D models
In the Boundary tab the program finds air cavities that are not completely closed and slightly ventilated ones, with minimum opening values the user can set. In imported models it happens that an almost invisible gap connects a cavity to the outside: the model is valid and the simulation runs, but the cavity is not treated as closed. Now the gap is shown and can be closed directly in the program.
3D import retries by itself with a finer weld threshold if the default one creates holes
If, when importing a 3D model (for example from SketchUp), the default vertex weld threshold leaves holes in the volumes, the program repeats the import with finer thresholds. Before, the right value had to be found by trial and error in the import options. The import also reports volumes that intersect each other.
Mold Simulator 3D: several components can now be selected and deleted in one operation
In the component list of the Lines tab you can select several components, or all of them, and delete them at once instead of one at a time.
3D views remember which volumes are hidden or in wireframe
The visibility of volumes, hidden or in wireframe, is saved with the view. When the view is recalled, also from a report label, you get the same picture of the inside of the model without hiding the volumes again by hand.
Psi linear elements and U areas now have distinct labels in the 3D view
In the 3D view, linear section elements, which give Ψ, and area elements, which give U, have labels that look different, so you can tell them apart immediately even in a crowded model.
Mold Simulator Dynamic
Real climate data, means calculated correctly to ISO 13788 and more control over time-dependent simulations.
Import of climate data from EnergyPlus .epw and .wac files into boundary curves
In the curve editor, import from file accepts EnergyPlus (.epw) and WUFI (.wac) climate files. You choose the quantity to import and the program shows only the data compatible with the type of curve: for a temperature curve, for example, the air temperature. Hourly data of a real location can thus be used in dynamic simulations.
Hourly climate curves are now averaged correctly in daily or monthly boundary properties
Some boundary conditions of EN ISO 13788 depend on the mean external temperature, not on the instantaneous one:
- daily mean: internal temperature and humidity for continental and tropical climates;
- monthly mean: internal temperature for houses, internal humidity from air changes and for maritime climates, ceiling temperature;
- monthly and annual mean: floor temperature.
If the external curve is hourly, the program now calculates the required means by itself. Before, with hourly data the internal temperature followed the external one hour by hour, and you had to remember to switch on the monthly mean option.
In dynamic simulations the radiant temperature of a boundary can now follow a curve
In boundary conditions with blackbody radiation, the radiant temperature, for example that of the night sky, can vary over time with a curve, which can also be imported from an .epw file.
Dynamic simulations can now use a custom number of time steps and saved steps
Besides the predefined quality levels there is a custom quality, where you choose the number of calculation steps and how many to save. The highest predefined quality calculates 5000 steps; a year has 8760 hours, so a whole year can now be simulated at hourly steps. More saved steps mean larger project files.
Adjustable playback speed for dynamic simulations
Right-clicking the playback control of the time-dependent results lets you choose the animation speed, useful when the evolution scrolls too fast to follow.
Fixes
Bug fixes and various improvements
Many fixes from the months of beta testing, including clearer warnings and messages in the mould check, in the handling of boundary couples and for cavities.
