Release Notes
Welcome to the official Release Notes of the Hysopt product portfolio. This page gives you a concise overview of all updates to the Hysopt product portfolio.
If an update is only applicable to a specific Hysopt product, the update is marked with the corresponding product label (e.g. Simulator-only, Calculator-only ).
All other updates are general software improvements available to all users.
For the Hysopt BIM Syncer, updates marked with 🔄️ require an update of the revit plug-in. This newest revit plug-in can be downloaded here.
Changes Nov 26, 2025
Hysopt is now available in Microsoft Edge
Hysopt compatibility has been extended to Google Chrome and Microsoft Edge.
As the application is cloud-based, users can seamlessly switch between browsers at all times.
New heat meter box for custom in-depth energy analysis Simulator-only
A new heat meter box is now available under Energy Metering in the Control library.
The meter can be connected to sensors across the system to combine multiple heat flows.
This feature enables custom and in-depth analysis of system heat flow behaviour.
Minor UI improvements and bug fixes
Corrected the Kv calculator help in combination with refrigerants (under Pressure drop in design parameters). Calculator-only
Improved robustness of CSV file downloads for more reliable data exports. Simulator-only
Extended DPI options of the pdf export for better resolution on exported schematics
Changes Nov 12, 2025
Upgraded heating end units with improved return temperature behaviour in part load Simulator-only
Added a representation parameter to indicate whether the Base Circuit (BC) represents a single end unit or a group of multiple end units.
When the representation is set to “multiple”, an advanced parameter called Return temperature behaviour factor becomes available.
The return temperature behaviour factor allows for more realistic return temperature behaviour of a single equivalent end unit (which represents a group)
The upgrade allows users to take control of return temperatures within physical boundaries, avoiding unrealistically low return temperatures.
Added a streamlined pareto export and energy report option Simulator-only
The exported Pareto report is now identical in layout and content to the in-Hysopt pareto version
The same streamlined pareto format now also applies to the energy report, providing a clean energy overview of the model.
Raw Pareto exports remain available for custom post-processing Simulator-only
Users with custom post-processing tools built on the old, static pareto export can continue using the raw Pareto exports.
The raw variant provides a comprehensive and consistent overview of all production components and energy flows in Hysopt, independent of the model content.
Minor UI improvements and bug fixes
Fixed incorrect medium propagation on both sides of the polyvalent heat pump.
Improved error messages for invalid uploads of COP/power data or data files.
Changes Oct 29, 2025
Upgraded graph copy-to-clipboard with more data options Simulator-only
Extra option to solely select the data values (y-axis), excluding the time axis
The new option allows for smoother post-processing in spreadsheet software
Added support for mass- and volume-based glycol mixtures
Glycol mixtures can now be defined as mass-based or volume-based mixture
More information can be found in Expansion vessel | General
Improved robustness of .csv export functionality Simulator-only
Improved robustness of exporting existing csv files from Hysopt
Minor UI improvements and general bug fixes
Added Danish krone (DKK) to the available monetary units Simulator-only
New error messages at low glycol mixture percentages to stimulate good design practices.
Fixed issue with auto-connect (Ctrl+A) when placing a zone on an end unit
Improved handling of the Enter key in the model explorer for smoother navigation.
Changes Oct 15, 2025
Introducing pipe heatmaps for advanced system-level analysis
Enable pipe heatmaps using the Pipe heatmap control window
Pipes are given a colour based on the selected variable using a scale detemined by the Scope and Mode settings
The feature allows a system-level overview to e.g. identify system bottlenecks or future extension opportunities
Component report: pipes are now grouped per application type Calculator-only
Pipes are now grouped per application type in the component list for a better pipe overview
Reintroducing tags to facilitate easy component grouping, see Tags
Easily make custom component groups by using the Tags framework (available when having a BC selected)
The tag framework allows you to create subsets of Base Circuits for e.g. fast group-level parameter adjustment or group-level Base Circuit movement
You can search for existing tag groups using the general Search
in the top ribbon bar.
Added search functionality to the operation list
A new search bar has been added to the operation list for to smoothen the workflow
Added AHU inlet overrides for more simulation flexibility Simulator-only
Three additional inlet condition overrides added to the AHU blocks (Inlet temperature, Inlet absolute humidity, inlet relative humidity)
The connectors allow users to decouple the inlet conditions from the external air conditions, enabling analysis of other use-case
Added AHU air flow connector for custom fan control Simulator-only
Additional output connector Air flow rate at the supply fan
The connector allows to implement a custom fan control without having additional duct sensors
Minor UI improvements and general bug fixes
Improved hover message readability during zoom-out
Added direct wiki links to all production unit Base Circuits for a more direct search on the wiki
Improved error messaging when encountering issues with custom pipe types/pressure profiles
Hybrid production parameters are now correctly updated in all design calculation steps
Resolved the wrong propagation of medium type at both sides of the heat exchanger for heating and cooling BC
Fixed translation of KV(s) in complex parameter window of Kv/KVs parameters
Changes Oct 1, 2025
Introducing break-into pipes
You can now snap components directly into pipes, allowing for faster and more intuitive model building.
Existing properties of the pipe are maintained over new pipe segments (exception: pipe length given to one segment)
New graph on controllers: setpoint when activated Simulator-only
A new graph has been added to controllers to display the setpoint whenever they are activated.
The feature makes it easier to troubleshoot and verify controller logic during simulations.
Improved handling of the temperature unit at room controllers Simulator-only
Room controllers now handle temperature units (°C/°F) more consistently across the Hysopt software
Minor UI updates and bug fixes
Introduced protection against illegal characters in parameter input fields
Improved robustness of new CSV file upload for column headers with number values Simulator-only
Bug resolve related to the temperature propagation over ventilation ducts
Changes Sep 17, 2025
Improved CSV Integration by adding customisation options in the user preference settings
You can now customise the column and decimal separator used in your CSV files, ensuring better compatibility with spreadsheet programs like Microsoft Excel.
Correct separators ensure automatic detection of columns and numbers in Excel and similar tools.
More information on the CSV format can be found in CSV Integration.
Added copy to clipboard functionality on graphs to quick transfer of Hysopt data to spreadsheet software (e.g. Excel, Google Sheets) Simulator-only
The functionality allows direct data transfer without downloading CSV files, enabling smoother integration with third-party software.
Introduced direct wiki link for more guidance on all Data file base circuits
The new feature makes it easier to find relevant documentation and guidance on specific base circuits.
More Base Circuits will be coupled to its corresponding wiki page in the near future
Improved fallback and retry mechanisms for more reliable solver Simulator-only
Complex models will now encounter fewer numerical simulation failures, ensuring a smoother workflow.
Improved unit display in dynamic labels and graphs
Simulation graphs of all Heating Curve BCs and Outdoor Air Temperature BCs now use the selected temperature unit. Simulator-only
The selected unit for the velocity quantity is now correctly applied in the dynamic label of pipes.
Minor UI improvements and bug fixes
Added extra validation checks when uploading CSV files Simulator-only
Bug fix: saving a continuously-on activation profile is now possible again Simulator-only
Changes Sep 3, 2025
Modified column added to the model explorer for better model navigation
A modified column is now added to models in the model explorer indicated the data when last saved
Better user guidance for parameters primary power percentage and heat flow on primary gate in all hybrid productions BCs
The primary power percentage is now an overrideable output parameter with lock icon (see figure below).
If unlocked: Value from primary power percentage (output mode) gets calculated from the heat flow on primary circuit (input mode)
If locked: primary power percentage (input mode) serves as input and the heat flow on primary circuit (output mode) switches to an output parameter
The implementation ensures that all hybrid production base circuits are now alligned with the input view
For more information on parameter types (input, output, overrideable output) in Hysopt, see parameter types
Better user guidance for heat exchanger parameters: UA value and primary return temperature
Design of heat exchangers can happen in two ways:
The primary supply temperature and primary return temperature are the inputs, from which the UA value is calculated during design calculations
The primary supply temperature and UA value are the inputs, from which the primary return temperature is calculated during design calculations
If the UA value is locked, the return temperature will now switch automatically to an output parameter for better clarity to the user
The implementation ensures the design of heat exchangers is alligned with the input view
New element tooltip with enhanced zoom behaviour
Enhanced zoom behaviour when zooming in
Updated the layout of the element tooltip
Efficiency table (COP, EER, TER, Boiler efficiency) file names of production units now remain saved in the model for better file tracking
If you update the efficiency table of any of the production units, the file name is saved to the Hysopt model
The change allows users for better tracking their files
Improved calculation of the room controller comfort levels when the activation signal is off Simulator-only
Comfort level of room controllers are now unaffected by the thermostat state during periods with Activation signal 0
The change improves usability of the comfort levels for ensuring no comfort issues are present in simulation
New graphs added to the auto-assign electric meter box and pump Simulator-only
Auto-assign electric meter box: Load duration curve added which allows for peak assessment of the total electric load
Pumps: Volume flow rate graph added to all pump base circuits for smoother simulation pump analysis
Minor UI updates and bug fixes
Updated the lock icon at overrideable output parameters
Improved precision of timestamps when downloading graph data as csv-files Simulator-only
Alligned order of matching simulation parameters of pipes and sensors Simulator-only
Setpoint and activation profiles are now supported as sensitivity inputs Simulator-only
Alligned order of DHW tapping types (shower, baths, …) over all occurences in the software
Added prefiltering of the current user to the activity list
Changes Aug 6, 2025
Introducing Input View, see Input View
Input view mode is now available and can be activated with the
button in the top ribbon bar
The input view highlights components with untouched inputs that are required to be changed to get valid calculations/simulations
The mechanism can be applied to mark components as Done or To Do for better project tracking
Customisation possibilities are available under user preference settings
Better user interaction for buffer vessel sizing methods
The chosen Volume determination mode now changes the design volume parameter to either input or output correspondingly.
The update improves the user guidance when applying sizing methods at buffer tanks (heating)
Added support for data files larger than 20 MB Simulator-only
Models with data files larger than 20 MB can now be saved and simulated.
Improved handling of invalid temperatures at ideal production units Simulator-only
Introduced error handling of invalid temperatures at ideal production units (ESIM012011)
Users are now guided to solutions via the message overview in this particular situation
Minor UI updates and bug fixes
Chart lines now use precise x-values for smoother curves Simulator-only
Updated visual of “on/off valve” Base Circuit, making it more discernable among all 2-way valve distribution circuits
Bug fix that caused duplicate error/warning messages
Changes Jul 23, 2025
Introducting new hotkeys (see operations 
"G" for Graphs: Quickly open graphs with the new G keyboard shortcut for faster navigation. Simulator-only
“Shift + G” for tichelmann pipes: Flip Tichelmann pipes direction with the new Shift+G keyboard shortcut.
Improved Decimal Separator Handling
A comma in user input is now automatically translated to a dot as decimal separator, reducing erroneous user input.
The dot separator is the uniform decimal separator in Hysopt.
Data Files: CSV File Name Storage Simulator-only
Data File Upload: the file name of custom files are now saved in the model
The update allows better project tracking by maintaining context of each uploaded file
Enhanced error message when wrongly combining application types
Hysopt now highlights the location at which applications are wrongly combined, reducing error search and solving time.
Most common example: accidentally combining a heating component in a cooling circuit
Minor UI updates and bug fixes
Updated the simulator view: Operation mode for pumps Simulator-only
Enhanced placement of date picker in simulation settings dialogue Simulator-only
Recovered correct display of calculation results at the expansion vessel BC
Changes Jul 9, 2025
Added extra simulation values (VWRT, PWRT, VWTD) to all pipes Simulator-only
Reduces the need for virtual sensors to retrieve relevant simulation data
Extra available simulation values:
VWRT: Volume-Weighted Return Temperature
PWRT: Power-weighted Return Temperature
VWTD: Volume-weighted Temperature Delta
Ideal production units are now capped to the maximal capacity Simulator-only
Ideal production units comprise the Fuel Boiler with Setpoint and Electric Boiler with Setpoint
These units now limit the output heat flow to the capacity of the unit, instead of simply providing the setpoint temperature
For an ideal unit without any capacity limitations, deactivate the Limit secondary heat flow toggle under advanced parameters
Improved transient end unit behaviour in changeover situations Simulator-only
End unit behaviour (radiator, underfloor heating, …) improved for more realistic behaviour in changeover situations
Controls and zones are now visible in shared models
Controls and zones are now visible in all shared models
If these libraries are irrelevant for your situation, you can hide them under Layers
Minor UI changes and bug fixes
Updated the calculator focus-view Calculator-only
Resolved minor bug with Tichelmann pipe system
Changes Jun 25, 2025
New Base Circuits available in the changeover library
Reversible heat pump with just a 2-pipe connection at the system side
Three types of storage tanks: 2-pipe, 3-pipe and 4-pipe storage tank
Passive dividing circuit consisting of 3-way valve in return
Buffer vessel graphs now show the height of temperature readings Simulator-only
The graph Temperature - Breakdown at buffer tanks now shows the height (bottom = 0%) of each temperature reading
BTES 1.0/1.4 simulations now correctly take into account glycol mixture properties Simulator-only
BTES 1.0 and BTES 1.4 encountered (small) energy flow inconsistencies when working with non-water medium
Those issues are now resolved, and might have a small impact on existing model’s simulation results.
Unsaved changes dialog updated with cancel option (Esc)
A clear cancel action has been added to the unsaved changes dialogue
Minor UI improvements
Improved user guidance when copying shared models
Mollier diagram updated to most recent version
Changes Jun 11, 2025
Added quota indicator in the job overview for running and available calculations Simulator-only
The amount of simulations are limited per user
The quota indicator in the activities overview
indicates the amount of running simulations against the available simulations
Improvement on pipes: Pipe label readability and heat flow graph are available at all pipes
The structure and readability of the pipe labels improved
Added heat flow graph at all pipes, reducing the need for sensors for analysis purposes. Simulator-only
Model Explorer: Ctrl+Click model now opens model in new browser tab
Allows to quickly compare models side-by-side over multiple browser tabs
New graphs available for utility meters and reversible heat pump BC Simulator-only
Electricity and gas meter: Load duration curve
Reversible heat pump:
Heating - Electric consumption
Cooling - Electric consumption
Enhanced behaviour of loading graphs after year simulations Simulator-only
Graphs of all selected BCs will now open correctly on first attempt.
Unconnected control nodes no longer block design calculations