Frequently Asked Questions

General questions about LCAbyg

Is it the latest guidance integrated with LCAbyg?

It is not the latest version of the guide included in LCAbyg. As changes are made continuously, you will always find the newest guide where you download the program.


Which version of LCAbyg is the latest that has been released?

Windows: LCAbyg 2023 (

Mac: LCAbuild 2023 (


Why do LCAbyg 2023 Windows ( and Mac ( have different version numbers?

We have had to make minor adjustments to publish LCAbyg 2023 on Mac. Due to adjustments, we have changed the version number to ( The database is the same version as Windows ( and still has the same problems.


Is there a version of LCAbyg for Windows 11?

The latest version of LCAbyg can be used on Windows 10. Downloadhere.


Is there a version of LCAbyg for Mac and Linux?

Mac OS version developed. Download here.
Linux is not currently supported but is potentially being developed.


Is there a difference between the Danish and Norwegian versions of LCAbyg?

Den Norske version er tilpasset de norske forhold også i forhold til levetider. Spørgsmål omkring dette henviser vi til


Can the order of materials be moved at the construction and building product level?

This function will not be implemented in LCAbyg 2023, but it will be looked into in future versions of the program.


Do you plan to structure building sub-groups and sub-groups as in the Voluntary Sustainability class?

Currently, LCAbyg is not planned to follow a classification system such as FBK, SfB, or similar systems. 


Is it a requirement to create environmental data from a specific calculation system when applying for a building permit?

There is no requirement that LCAbyg 2023 or other tools be used to document a building's climate impact. Therefore you decide which program to use. However, you must be aware that specific programs may be mentioned in the tender material.


ATTENTION: It is not possible to open LCAbyg 2023 projects in LCAbyg

If a project has only been opened in LCAbyg 2023, it cannot automatically be downgraded to an LCAbyg project.


Why does LCAbyg 5 look very large on my computer screen?

The reason may be a setting on your computer, which results in LCAbyg looking great. Feel free to check this out first.

Otherwise, there is an option for scaling in the upper right corner of LCAbyg. Remember to restart LCAbyg.


Is it possible to compare different variants in the same project in LCAbyg 5?

It is possible to work with several different scenarios in a project. Therefore, it is possible to work with different calculation assumptions for each scenario. Scenarios are activated under "Building and operation" on the button. "Click to enable scenarios for this project." This function replaces the project comparison function that was discontinued in LCAbyg 3.2.

General questions about LCAbyg - results

As a developer, how do you check that LCA calculations submitted to the authorities are correct? Can we "only" check that the result is below 12 kg/CO2?

Please contact Videnscenteret for Klimapåvirkningerne or the authorities.

The report from LCAbyg 2023 is prepared to give a complete picture of one’s building model.  Theoretically, it should be possible to recreate the same building based on the report only. 


Why is the sum of the different stages different from the key numbers in my LCAbyg report? 

The results in LCAbyg are rounded with the "Banker's rounding" method, which is the most numerically stable method for rounding numbers, where x.5 is rounded to the nearest even number. Therefore, the result may vary due to this rounding method.


The tab on the left of the results page shows the result that was clicked on

If a component is selected on the results page, it will be displayed in the left tab. This means that different values may appear. 


Why can't I export a report to PDF?

The report function in LCAbyg and is sensitive to incorrect naming of user-created building parts, constructions, building products, and phases.
Furthermore, you must avoid putting a space with 'tab' and end up making a line break. We always recommend downloading the latest version of LCAbyg.


Is it possible to export LCA-results to an Excel-fil?

The LCA results for the building model can be exported to an Excel file. Under the menu item 'Results,' you can select 'Export Excel,' after which the destination where you want to save the Excel export is selected. With this, all results on the building model are available.


Is it possible to save the analysis graphs in SVG files?

You can save the charts in LCAbyg 5 as SVG files under 'Analysis and report' via the 'Save chart' function.

General questions about LCAbyg - EPD's and stages

ATTENTION: When copying data from EPDs

LCAbyg works with commas; you should be aware that some EPDs use periods as commas. This could yield a higher result.


ATTENTION: EPD Danmark construction product in the project

An error code will be displayed when importing an EPD Danmark building product that is part of GenDK. This happens because having the same construction product twice is impossible.


Why can't I see my imported EDP files in LCAbyg 5?

The imported EDP file (.lb5epd) will appear in the building item or stage library, which can be accessed via the book icon.


Unable to create a stage

Check the following:

  1. Always fill from top to bottom. It is important that the general information is filled before entering the indicators.

  2. If you are copying indicators from a pdf or something else, be aware that there are no spaces before and after the numbers. If the box with indicators is red, it means that the stage has not been added.

  3. When entering the indicators, note whether it is (,) or (.). LCAbyg only understands (,).

Errors in LCAbyg (published 2023)

The description of constructions for default values is incorrect

The amount must be equal to the heated floor area §256 subsection 3, plus the heated basement area


The area in the report has been swapped

In the table "Areas" of the report printout, Integrated garage and Additional area are swapped in a way that causes the numbers to have the wrong position. This does not affect the final result. 


Comma numbers are not visible in Calculation prerequisites.

There is a display error which means that when commas are entered in Integrated garages and Additional area, NaN is displayed. This is a display error; the number is still counted in the Reference area.


Error in GenDK constructions

Some constructions in GenDk have demolition turned on, which means that A1-A3 is not included in the calculation. This can be changed by cloning the build and manually turning demolition off.


Error in the lifetime table (DK: levetidstabellen)

Individual rows and columns are not shown in the lifetime table in LCAbyg v. 5.3. The entire table can be found in the BUILD REPORT 2021:32 – BUILD levetidstabel – Version 2021 (revised in November 2022 as version 2).


Error in constructions containing lightweight concrete and plaster

In GenDK constructions that contain "Lightweight concrete wall element, 100 mm thick wall (10% recesses)" and "Gypsum fiber board 10 mm", the building product is not included in the life cycle assessment due to a unit error. This can be remedied by cloning the build and then changing the unit.

ATTENTION: It is important to check whether the quantities make sense using the construction library. 


Error in the construction "Columns, concrete frame column 300/300"

The construction has a steel profile as a construction product but should have reinforcement


Silicate paint (indoors) has incorrect C3 stage

The building product has a concrete element in the C3 stage, which is incorrect according to the generic database.


Error in the default values ​​for other buildings

Other buildings, drains A1-A3

LCAbyg value: 0.125 kg CO2eq./m2

Actual value: 1.125 kg CO2eq./m2

Other buildings, water, stage D

LCAbyg value: -1.675 kg CO2eq./m2

Actual value: -1.28 kg CO2eq./m2


Missing stages in several concrete building products

When opening the LCAbyg project in LCAbyg 2023, in some cases, stages may be missing in the concrete building product.

New features in LCAbyg 5.3.10 (published December 2023)

More area entries under 'Calculation prerequisites'

In calculation conditions, it is now possible to enter the area of ​​integrated garages for single-family houses, terraced houses, and the like, which are included at 50 percent. cf. the requirements on the climate impact of buildings, as well as an additional area which is included at 25 percent.


Import of emission factors from local supply facilities

It is now possible to import an EPD for a supply source if there is an encrypted and 'locked' .lb5epd file for the EPD. At the time of publication of LCAbyg 2023, EPDs from utility companies still need to be published. There will be more about this in the user guide and webinars when it becomes available.


Natureal gas has been replaced by pipeline gas

The emission factors for natural gas have been replaced with new emission factors for pipeline gas. See more about the data behind the operation in the associated Excel sheet, which can be downloaded at the same place as LCAbyg. 


The lifetime table (DK: levetidstabellen) has been updated .

The lifetime table has been updated cf. BUILD REPORT 2021:32 – BUILD levetidstabel – Version 2021 (revised in November 2022 as version 2), which can be found her.


Special circumstances

If a building has special conditions, these can be added to the program, after which the given constructions covered by the special conditions can be selected in the building model. The additional impact due to special conditions for which the building is justified is then calculated. Read more about special building requirements in the new BUILD report 2022:27 her.


New display of the library

The display of the construction and construction material library has been updated. Getting more information about constructions and construction materials in the library is now possible.


Stages can be created cf. EN15804+A2

It is now possible to create stages according to the available EPD standards - both EN15804+A1 and EN15804+A2. When entering stages according to EN15804+A2, only the GWP-total indicator must be entered. Please note that the project will use environmental data from two standards when entering one or more stages according to the standard EN15804+A2. Therefore, the results for indicators other than GWP cannot be compared or summed. There will be a warning in several places in the program if EPDs from EN15804+A2 are used.


Scaling factor

All stages now have a scaling factor. The scaling factor can, e.g., is used when entering insulation materials, whereas, in an EPD, there is an associated table to scale to the material that must now be used. If the data set does not contain a scaling factor, this is set to 1.


Results display updated

It is now possible to close the display of results for the various environmental indicators and thus only display results for individual environmental indicators rather than all. By default, LCAbyg 2023 only shows results for the environmental indicator GWP when the calculation condition is set to "Building Regulations"


New result display for the building regulations (DK: Bygningsreglementet)

When selecting the calculation type 'Building Regulations', there is now a new results page called 'Building Regulations'. It provides a simple overview of the main results for the building's climate impact, which must be used to document the upcoming requirement for buildings' climate impact in the Building Regulations.


English version

Under settings, you can now change the program interface to English.

Report updated

The LCAbyg report has been updated and can be used to document the building regulations' requirements for buildings' climate impact.


Import of ILCD+EPD format

It is now possible to import EPDs in the digital format ILCD+EPD. From 1 January 2023, EPDs can be imported from EPD Norway, with a few exceptions for materials whose digital file needs the necessary information to be used for Life Cycle Assessment in LCA building. For more information see her.



LCAbyg's LOG is now updated to be more interactive so that you can double-click on any missing or errors in the LOG which directs you to the exact location of the error. 


Opening of LCAbyg projects

It is now possible to open LCAbyg projects by double-clicking on the files. However, this only works as long as the project is not destroyed. In that case, the LCA building must be opened first, after which the project can be opened and possibly repaired. ATTENTION: Be careful with double-clicking on files that will not be updated to the latest LCAbyg version.


Repair of LCAbyg projects

LCAbyg can now repair projects that have previously been destroyed. Most projects from, e.g., previous versions, can now be opened in LCAbyg (not by double-clicking the file), and you will get a message here that you can repair the project. Remember to save your original project, as there may be information that LCAbyg removes in connection with improving the project. Projects that have been repaired must be saved as new projects.


Shortcut keys

It is now possible to use shortcut keys in LCAbyg to access the various functions such as: renaming, removing, etc. These shortcut functions can be seen in the LCAbyg program by hovering the mouse over the function.

GenDK updates

Adapted to meet legal requirements

GenDK has been updated and adapted to "Appendix 2, table 7: Generic database 2023". This update includes replacing generic data for concrete and wood materials with industry data from EPD Denmark. The database can be downloaded from:  In addition, the GenDK library is further updated for any defects. Projects created in LCAbyg or earlier will potentially vary as the database has been updated. Older projects opened in LCAbyg 2023 will automatically be updated to the latest database and cannot be rolled back to a later version after this.


New constructions

The construction library has been updated with more constructions. Among other things, standard values ​​have been added for installations that BPST has developed in collaboration with the industry.

Features no longer available in LCAbyg

Import of LCAbyg 3.2 projects and components

With the release of LCAbyg 2023, it is no longer possible to import projects or components (Building parts, Structures, Building Materials, and Stages) from LCAbyg 3.2. If the need arises, you must open these in LCAbyg, save and then open these in LCAbyg 2023. If, contrary to expectations, problems occur with opening projects from LCAbyg 3.2. in LCAbyg, then write to the LCAbyg mailbox.


DGNB as calculation type

As a result of the new DGNB manual applicable from March 2023, where documentation requirements for life cycle assessment are streamlined with the building regulations, the DGNB calculation type is taken from LCAbyg 2023. This means, in return, that new DGNB certifications must use the calculation type 'Building Regulations' to document the LCA criterion in DGNB. Point calculation is done elsewhere. Information on DGNB certification types can be accessed here:

General questions about LCAbyg JSON

Which third-party integrations can be used in LCAbyg 5?

It is possible to use the JSON format as third-party integration. Integration via IFC is under development.


What is the JSON format?

Third-party integration used outside LCAbyg's interface to create everything from entire projects to component libraries. It is also possible to extract results for his project in JSON. Watch or re-watch our webinar on the intro to the JSON format on LCAbyg's Youtube channel.


Where can I find a guide about the Json format?

There is an English guide to json projects which can be downloaded here.

We are currently updating the guide and dividing it into several short guides (json guide project, json guide export, json guide scenarios, and json guide components).

An updated version of json guide export can be downloaded here.

An updated version of json guide scenarios can be downloaded here.

Updated versions of the json guide project and json guide components will be published at the beginning of March 2022. The guides are continuously updated, so you must always download the latest version.


Where can I fint the import example?

You can find the import exmaple in the zip folder when you down the Json guide here: User manuals and other tools

Updates in LCAbyg JSON

Version has a change in engine.yalm.

See the example under Step 3.3, page 15, in the JSON guide. The guide can be downloaded here.

Typical error messages in LCAbyg JSON

LCAbyg_debug.exe will not open or crash when I try to open my Json project.

Check that the file 'engine.yalm' has no errors. Typical errors include incorrect indexing, incorrectly placed characters, e.g., character. To help troubleshoot, type 'cmd' and press 'enter' in the path where lcabyg_debug.exe is stored. This will open a terminal describing errors in your engine.yalm file.


How can I check that my JSON files are correct?

We recommend that you regularly test that you import your JSON project into LCAbyg. By opening LCAbyg_debug you can get error messages printed in the LCAbyg terminal. LCAbyg does not work if you place the cursor or type inside the terminal, and if you make changes to the JSON project, you must restart LCAbyg_debug.You can read more about the debug feature in the updated guide on JSON projects (coming out in early March 2022).


How can I find out why I get the "Missing UUID" error message in the LCAbyg_debug.exe terminal?

You can search your JSON file/files in Notepad ++ and check that all UUIDs are written correctly, that you have not inserted the UUID incorrectly, or that you must include UUIDs.


Why does the same error message appear twice in the LCAbyg_debug.exe terminal?

It does not affect the overall error. Both error messages will disappear by resolving one of the two identical errors and restarting LCAbyg.exe.


What does the following error message mean: 

"Collision between CategoryToConstruction(069983d0-d08b-405b-b816-d28ca9648956) and ElementCategory(069983d0-d08b-405b-b816-d28ca9648956"?

Often this error is because the unique ID has been used more than once. Therefore, check that the unique ID or referring unique ID has been used only once.


What does the following error message mean: 

"Missing target source at badfcf92-804a-5902-a5c4-0ea1460c202e for ConstructionToProduct(0dd0b7a2-6f15-496c-88e0-8b64bcb663ba)"?

If you have created node and edges for nodes, and then deleted some of nodes, then the referring/related edges must also be deleted. One way that "blank" edges can be found quickly is by opening the JSON project in Nodepad ++, then performing a search on "amount: 0", which returns the search result for all blank edges in the searched JSON file/project.


I cannot find any constructions when I export the building model from LCAbyg to JSON.

If you have only used the gen_dk library to model your constructions, then no constructions are exported to JSON, as they are already in the gen_dk folder, built into LCAbyg.


Why do I get the error messageCollision on Building…", when importing a component for an existing project in LCAbyg?

One reason may be that your import component is not set up correctly or that you have imported a non-UUID component already in an LCA building component.


Why can I not open the import example?

This may be because you are using different versions or, respectively, the import example and LCAbyg. For example, a change has been made to the edge, CategoryToStage, from version to You must download the latest version of LCAbyg and the latest version of the JSON guide.

Excel tool (lite)

What is Excel tool (lite)?

The Excel lite tool can be used to build the building model via Excel, intended for the earlier design phase and faster import of the building model.

Excel lite is continuously developed. If there is feedback, you can write to the lcabyg mailbox


Is there a guide to Excel tool (lite)?

Introduction and help can be found in a sheet in the Excel file, which can be downloaded here.


Is there a version of Excel tool (lite) for Mac?

Currently, the Excel tool does not work for Mac (import of the csv file). This will be developed soon.


Why do I make a mistake when copying a row?

To copy a row, paste it at the bottom / below the existing rows.

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