• Discuss modelling ideas
  • Ask for advice from Facilia’s experts
  • Access to model components while writing equations
  • Auto-completion
  • Listing of available functions
  • Parenthesis highlighting
  • Create model components as you type

  • Quality assurance
  • Expert review
  • Statistics, values, time series, distributions
  • Attach documents
  • References
  • Naming conventions
  • Fully integrated with Ecolego via Parameter database toolbox

Box diagrams

  • Work simultaneously with box diagrams and interaction matrix
  • Supports background pictures
  • Nested containers that can be collapsed
  • Layout managers

Sensitivity analysis toolbox

ODE toolbox

  • Handles both linear and non-linear systems of ordinary differential equations
  • Fast and reliable solvers
  • Solvers for stiff systems
  • Variable step-size
  • Sparse matrices used for large models

Ecolego will soon write your reports for you

Well, not really, but we are working on a new feature to generate Microsoft Word equations from your model. To test it out:

  1. Right-click a block anywhere
  2. Choose Export > Lite report

Ecolego 6.5 is out!


MERLIN-Expo Logo

Merlin-EXPO is a free tool for simulating the fate of chemicals in the main environmental systems and in the human body, funded by the EU 7th Framework Programme. It is based on Ecolego Player and features a library of models for both metals and organic compounds. MERLIN-Expo is unique in that it allows tracing a contaminant from a release point via all exposure pathways to an organ in the human body. By basing the software on Ecolego, the tool supports both uncertainty and sensitivity analysis. MERLIN-Expo is of special interest to those needs a deeper understanding of a specific scenario than offered by EUSES.

For more downloads, tutorials and wikis, please visit https://merlin-expo.eu.

Ecolego 6.3 Release Candidate available

If you want to test the new version 6.3 version of Ecolego, head over to the downloads section. Note that this release is not 100% forward compatible with older versions of Ecolego, meaning that users with older versions of Ecolego might have problems opening projects saved with this version. Like always, Ecolego is 100% backwards compatible. You can have both Ecolego 6.2 and 6.3 installed on the same computer.

The new release of Ecolego is bundled with Java 8 which is why you need to download the installer.

The main changes, except for numerous bugfixes, are related to how Ecolego handles multidimensional results.

Ecolego 6.2.15 released

A new maintenance release is available for download. It features, except for some bug fixes, for large models with multidimensional objects.

Ecolego 6.2 released

Ecolego 6.2 is now available for download. This release has focused on simulation speed and new modelling tools.

Main new features:


  • Multidimensional objects: A block can now have any number of dependencies - this includes compartments.
  • The Library functionality has been completely rewritten. Re-using your models is easier than ever.
  • Arguments for expressions and lookup tables.
  • A new block Aggregate will make it easier to sum, multiply or perform other operations on many blocks.
  • Parameters can now be assigned more statistics (mean, std, N etc). The statistics can then be used for probability density functions.
  • The radionuclide toolbox now allows you to create a dedicated parameter for radionuclide halflifes.


  • Comments can now be written for all objects. All comments are listed in the comment window.
  • The modification date is now recorded for every object. A visual hint let you easily see which objects have been modified since the project was opened.


Up to 20 times faster simulations for large models!

  • Reduced memory footprint for batched simulations
  • Stiff solvers now allows using a new linear system solver for very sparse models, which can perform more than twice as fast.
  • Stiff solvers now takes full advantage of the sparsity of models, which decrease simulation time drastically (x10) for very large models.
  • Reading and writing the simulation results is now done using memory mapped files, resulting in much faster plotting and result linking.
  • The memory footprint has been greatly reduced for all simulations.
  • Simulation code optimizations for transport blocks.

Added simulation settings make it easier to diagnostisise simulations and to run probabilistic simulations.

  • Advanced simulation settings flag “Output statistics” allows user to see time of each iteration, number of errors etc. for probabilistic simulations
  • Advanced simulation settings flag “Timeout” allows user to set time limit on a simulation
  • Advanced simulation settings flag “Halt at error” allows user either stop the simulation when an error occurs or continue
  • Advanced simulation settings flag “Debug” now split up into two: “Display statistics” and “Add check for NaN/Infinity”

User interface

  • Spanish language support!
  • Project window?, Matrix window and Blocks window all have several new filters that allow you to search for items quickly.
  • Auto-button for settings which support “auto”
  • Many more PDFs now allow the “auto” setting for parameters
  • Optimizations for objects with >100 indices

Smaller miscellaneous changes

  • Adaptive absolute error tolerance setting which increases absolute error tolerance per-state during the simulation.
  • Warnings when tables or charts with too many data items are created.
  • Buttons to add or remove tags for a selected object. Select objects, right-click, choose Apply>Add tags… or Apply>Remove tags…
  • Add again (from library) short-cut (SHIFT+ALT+CTRL+T), which can be used to add the same item from the library as last time.
  • Proper keyboard accelerator short-cut for “Get from library…” menu button (SHIFT+ALT+L)
  • Edit comment button for the comment window
  • Warning/error message when no values have been found for definitions during import
  • Descriptions for individual indices
  • Made the glossary edit window a little more compact
  • Progress window when generating PDF report
  • Parameter summary in the reports now sorts parameters by category.
  • Blocks, windows, table headers and items are now sorted alphabetically.
  • Mathematical functions “mean”, “sum” and “product”
  • Revert to last save menu button (closes and re-opens the current project - poor mans “Undo”)
  • Recent script menu
  • The project window now inserts a symbol before the name of objects that have changed since the project was opened.
  • Option to turn off auto-connect when importing sub-systems from the library.
  • Option to close existing project when opening a new project with the same name.
  • Possibility to clear blocks of their data before importing.
  • Log created when importing from Excel.
  • When exporting parameters or other blocks to Excel, all definitions can be written to the first sheet (with values on subsequent sheets)
  • Drop-down button for quick access to probabilistic/sensitivity/scenario simulations
  • Drop-down button for quick access to probabilistic/sensitivity settings
  • The buttons for hiding/showing default values in the block editor window are now located in the lower right corner.
  • General variable window now displays full name (if available)
  • Look and feel for workspace
  • Matrix label font scales to fit cell
  • Glossary now includes units, categories and descriptions
  • Buttons for turning off quick chart/table creation in results window
  • Validation speed up
  • When changing from the default block picture to a new one, the color on-off option is set to off.
  • Icons instead of text for buttons when editing blocks.
  • Button for hiding not-so-common columns when editing blocks
  • Buttons to hide default values or indices when editing blocks.
  • “Close all” button for charts and tables.
  • Name and sub-system search filters for available general variable objects
  • Name of the preference “workspace directory” to “temporary files”.
  • Filter to index operation editor
  • Mean value can now be calculated using index operations
  • Glossary editor much improved
  • Export default value, export default indices, export properties always options for export to Excel
  • Recent filter when adding radionuclides.
  • When creating a connector between two models, all inputs with name matching outputs in the target model will be automatically connected.
  • Lines connecting boxes in a graph can now be split into segments by adding waypoints. Waypoints are added by either right-clicking a line and selecting “add waypoint” from the menu, or by left-clicking while pressing the SHIFT key.
  • Symbols for unconnected inputs and outputs
  • Batches for nuclide chains support
  • Chart and table tabs can now be closed
  • A symbol on tables, trees or lists to highlight when a filter is active
  • Select scenario dependent objects from the menu in Scenario window.
  • Select project menu (under Window)
  • A symbol on tables, trees or lists to highlight when a filter is active
  • Rudimentary support for external models

Presentations from an Ecolego 6.2 presentation (September 20th 2013)

We are finalizing Ecolego 6.2 and made a presentation of new features. If you want to know what’s in the pipeline, check it out!


Ecolego 6.1

The Ecolego 6.1 release contains a lot of new features:

  • Simulation results can be exported to file or imported from file
  • Lookup tables and parameters can now be linked to simulation results
  • New type of sub-system called Group
  • Import/export all types of blocks (not only lookup tables or parameters) to Excel or Database
  • Tag objects (as an alternative to assigning category)
  • Russian language support
  • Create and use a glossary for your models
  • Compare table
  • Define scenario dependent parameters in Ecolego Player
  • Right-click a table header to show/hide columns
  • Description editor now has buttons for headers, lists, superscript, subscript etc.
  • Select which properties to export to Excel
  • Improved synchronization between Ecolego and Excel data
  • Ecolego Player now features the Graph window
  • Drag n’ drop files from desktop to Ecolego
  • Quickly jump to next/previous object when editing objects

For a full change log, click here!

Ecolego 6

Ecolego 6 released!

  • New license model
  • Support for running simulations of multiple scenarios
  • Archive and compare results from different simulations
  • Design models using box and arrow diagrams
  • Assign default values for specific index lists

Presentations and exercises from the workshop (October 17 2011)

To access the presentations and exercises from the Ecolego Workshop, please follow the link below:


Ecolego Workshop 2011 (April 12 2011)

The date for this years Ecolego Workshop has been set for the 10th-14th of October.

For those of you who have attended this course before, the setup is as usual:

We start off with a two-day crash course in Ecolego basics. After that follows a two-day presentation of new exciting features both in Ecolego 5 and in the upcoming new release: Ecolego 6. On Friday we finish the week with a seminar where the participants are welcome to present their current work in Ecolego and discuss solutions to problems.

For more information, please contact us at ecolego@facilia.se.

Ecolego on Wikipedia (March 9 2011)

Ecolego is now available on Wikipedia! Check it out:


Update of Ecolego (January 7 2011)

New features:

  • The sensitivity analysis toolbox has been completely re-written and has a new user interface and several new options.

  • The report settings window has been updated, and the report has been much improved. There are now three report-templates available to quickly change the report settings.

  • All buttons now have correct short-cuts and mnemonics.

Update of Ecolego (November 23 2010)

New features:

  • Model inputs and model outputs can be limited to only accept connections to one other output/input.

  • The auto-connect feature can be turned off for a specific Model inputs / model output.

  • Objects can be “locked” by setting the “Editable” flag. This is useful if you wish to distribute a model via Ecolego player and do not want the user to change specific values.

  • Objects can be “hidden” by unchecking the “Visible” flag. This feature only applies to when the model is displayed in Ecolego Player.

  • As a move towards the much-requested feature Undo/Redo: Ecolego can now help you track changes to a model. This feature is not fully complete yet but is still useful enough to be included in this release. To enable change tracking, open the new history window? and click the toolbar button. Or, from the Edit menu; select “track changes”. After “track changes” has been activated, changes to parameter values will be highlighted in the parameter tables and in the report.

  • The statistics table has been blessed with many more statistics options.

  • Many bugfixes

Downloads from the Ecolego Workshop (October 15 2010)

The Ecolego Workshop 2010 is now over. All the slides and exercises from the course can be accessed by following the links below:



Update of Ecolego (September 17 2010)

New features:

  • General variables can now be assigned different values depending on index. This makes it possible to create models where the user can select which calculation should be performed for a specific substance. For instance, consider a model with a general variable for a distribution coefficient. The user can now select which way the distribution coefficient is calculated depending on substance.

  • The report has now been repolished and several bugs related to the report has been fixed. It is now also possible to save templates for the report from the report settings window.

  • Many small bug-fixes

Ecolego Annual Workshop (July 23 2010)

As the vote was unanimous, the dates for the annual Ecolego workshop has been set to 11th to 15th of October.The workshop will be held close to Facilia’s main office in Stockholm, Sweden.

Preliminary agenda

Monday/Tuesday - Beginners course in Ecolego.

  • Learn to use the basic functionality of Ecolego.

Wednesday/Thursday - Advanced Ecolego.

  • All new features of Ecolego 5 will be explained.

Friday - Ecolego applications

  • We wish to invite our customers to present their work with Ecolego

If you are interested in joining the workshop, please register by sending us an e-mail letting us know which days you wish to attend and if you wish to make a presentation of your work on the final day.

Eikos Java beta version available (June 23 2010)

We have for some time been working on a stand-alone version of Eikos that does not require Matlab.

An early beta version is now available for download in the downloads section. Eikos Java will be free of charge while being beta tested.

5.0.78 Update of Ecolego (June 23 2010)

This update fixes minor bugs related to the library and copy/paste.

5.0.66 Update of Ecolego (May 25 2010)

New features:

  • Web proxy host and port can be specified for when retrieving updates. In most companies, all web traffic is directed via a proxy, and this has prevented people from receiving automatic updates. To edit the proxy host and port, go to File|Preferences and open the Startup page.
  • Off-line help bundled with Ecolego, so that the help documents can be browsed without connection to the internet
  • Search field for help in the main toolbar
  • New block: discrete event. This block should be used in combination with conditions, so that the solver discovers important time points in the simulation.
  • The recorder block has been updated to take two arguments rather than one for reset/record.
  • The recorder block has been updated to support calculating the mean value of a given output.
  • The matrix window now displays icons for adding empty cells in its title bar.
  • The results window displays icons for the outputs that match the icons in the project tree. This makes it easier to see which type of object is behind the output.
  • The information window now displays graphs for lookup tables.

5.0.45 Update of Ecolego (April 23 2010)

New features:

Linear incrementing timeseries
This is an alternative to the normal linear time series. Instead of specifying the number of time points to create, specify an increment. This makes it possible to, for instance, create a time series where output is given for each day, independent of what the start and end time is.
Min and max available options for probabilistic data
When creating an index table you can now ask for the min, time for min, max or time for max for statistics from a probabilistic simulation. For instance, show me the time for the maximum mean value, or the minimum of the 5th percentile.
Min and max available options for probabilistic data
When creating an index table you can now ask for the min, time for min, max or time for max for statistics from a probabilistic simulation. For instance, show me the time for the maximum mean value, or the minimum of the 5th percentile.
New solver
A new solver, RADAU5 is available.
Solver descriptions improved
The descriptions for all solvers and the situations in which they are used have been improved.
Quick block create
To quickly create a block in the Blocks window:
  1. Enter the name of the block in the search field.
  2. Select the type of block in the type drop down list.
  3. Select a sub-system from the sub-system drop down list.
  4. Select a category from the category drop down list.
  5. Click the New button.
Debug mode for simulations
The debug mode has been improved to not only report statistics from the simulation, but to also interrupt the simulation if any calculation is NaN or Infinity. An error message will report which block has caused the problem. Debug mode can be set from the advanced page in the simulation settings window.
General variables available in player
There is a new screen called "Options" in Ecolego Player for selecting targets for general variables.

Ecolego Annual Workshop (April 7th 2010)

We would like to invite you to the annual Ecolego workshop in Stockholm.


  • Day 1,2: Crash course in Ecolego usage. Basic training for people that have not participated in earlier Ecolego workshop training or feel like they need to refresh their knowledge.

  • Day 3: Training in all new features of Ecolego 5. Become an expert in unit checking, building libraries and in committing projects to version control.

  • Day 4: Presentation of Ecolego use-cases. By workshop delegates and Facilia staff. Have you been involved in an interesting application of Ecolego? Let us know and you can present your work this day.

  • Day 5: Problem solving and customer specific assistence. Bring your modelling headaches and questions and we will solve them together.


We suggest the following two alternative dates.

May 24th-28th

June 7th-11th

If you are interested in joining the workshop, please let us know the dates for which you are available. You can select the dates here.

Last day to register

Please let us know before April 30th if you wish to participate.

Ecolego 5 released (April 2nd 2010)

The new version features:

Ecolego web site launched (April 2nd 2010)

The new Ecolego website is the main resource for all things related to the Ecolego suite of programs. Here you can:

  • Get information about Ecolego
  • Purchase Ecolego products
  • Download and upload models
  • Find documentation for Ecolego products
  • Access the Ecolego forum