NollCO2 is a certification system developed by Sweden Green Building Council (SGBC) and their members aimed at steering the construction industry toward net zero carbon buildings. This is done through a combination of reduced climate impact and balancing measures over the lifecycle.

The latest version is currently NollCO2 2.0. The NollCO2 tool in One Click LCA is approved by the SGBC for this version of the certification.

This article describes how to use the NollCO2 tool in One Click LCA. For detailed methodologial guidance for the certification we refer to the official NollCO2 manual "Nybyggnad och ombyggnad 2.0" (Sweden Green Building Council, 2024).

NollCO2 follows the EN 15978 standard. The life cycle stages A1-A5, B1-B7 and C1-C4 are included in the tool, although B1 and B3 are not mandatory to include as per the NollCO2 manual. The D stage is excluded from the certification system boundary, however the calculation tool reports this as additional information.

The service life of the building should be set to 50 years.

The functional unit, reported on the Results page in the tool, is kg CO2e/m2 Gross Floor Area.

In the NollCO2 tool, you can find data created according to both standards EN 15804+A1 (CML) and EN 15804 +A2 (PEF).

The NollCO2 manual specifies a hierarchy about what data should be prioritised to use in the calculation. Climate data with a higher priority should be prioritised over a lower priority, if data is available. Data according to all priorities can be found in One Click LCA. If you want to only find data from a certain priority category, you can use database filters to speed up your search.

* Typical data is data without the conservative top-up factors of 25 % for Boverket data and 20 % for CO2data. In One Click LCA, the NollCO2 tool automatically uses typical data for Boverket and CO2data as specified in the certification.

** One Click LCA provides an automated function customised for NollCO2 for adding the 25 % top-up factor on material-level which can be used for LCEs and proxy-EPDs. Read more in the Guidance section below under the sub-heading "Tips for working with the NollCO2 data priority order".

The building types that can be certified and the building parts that are included in the assessment scope can be found in the NollCO2 manual (Sweden Green Building Council, 2024), pages 15-19.

The certification scope includes future scenarios to reflect the future decarbonisation of the electricity grid. This means that emissions occuring in the future should take these scenarios into account. This is done in One Click LCA based on the equations for future scenarios given in the NollCO2 manual, one for B6 and another for B1-B5, B7 and C1-C4. This is further explained in the section "Future Scenarios" below.

Create your Project and add the tool "LCA for NollCO2". Additional guidance for this can be found in the articles Creating A Project and Managing Calculation Tools in Your Projects and Designs.

Project LCA Parameters are default settings for your calculations. They will affect calculations and results across your project. General guidance for ths, including how to change the parameters, can be found in the article Selecting Project Parameters.

In the NollCO2 tool, default values for transportation distances, transportation profiles and site wastage are always based on the Boverket default values for the respective material. Below is a summary of LCA parameters in the NollCO2 tool.

Please note that you can manually change from the default values for any material in the building materials query.

In this section, the different input queries in the tool will be described.

In this section, the columns in the Building Materials query will be explained. Suggested ways of working with the data according to the NollCO2 data hierarchy will also be discussed.

In One Click LCA, data can be added manually or through import of bills of materials in Excel, IFC files or BIM models. A collection of helpcentre articles explaining how to import data, including guidance on the import process, AI mapping and various BIM integrations can be found here: Data Integration & Import.

Searching for and adding data in the tool

Use the search function in the tool to manually find materials by entering keywords such as material name, EPD number, manufacturer, type of material etc. Search for the material in the search box in the building part section where you want to add the material. You can use the "Move material" function if you want to move materials between different sections after you have already added them to your calculation.

Filters such as material type, country data source, type (generic or specific data), CO2e impacts, unit or standard can be used to speed up or specify the search.

If you click on the green question mark next to a datapoint, you will open its datacard where you can find a lot of useful information such as environmental impacts, background information and a decription of the resource.

When you add a datapoint, you can enter the quantity and specify the unit. After you click on 'Save', the climate impact of each row will be calculated. The share of each row's contribution to the total climate impact in the design is also shown.

If you click on the green result number, you can see the detailed calculations of each material broken down per lifecycle stage.

Tips for working with the NollCO2 data priority order

The NollCO2 has a priority of data as explained above in the Section "Data Scope". Here are some tips and tricks for working with these different data categories.

If you have not applied any filter, data from all priorities that matches your search words will appear. If you want to see only data from a certain database, such as Boverket, CO2data or Ökobaudat, you can select that database in the "Data source" filter. If you, for instance, want to see only generic data but from multiple databases at the same time you can select "Generic" in the "Type" filter. Similarly, you can choose "Manufacturer" if you only want to see EPDs.

As explained above, typical data from Boverket and CO2 data should be used. This is done automatically in the tool when data from these databases are added to the calculation.

LCEs and proxy EPDs should have a top-up of 25 %. This can be applied for any material by checking the box "Simplified LCE" to the right on the respective material row.

When using LCEs, the NollCO2 manual specifies that the percentage of each material in the building product declaration (SE: byggvarudeklaration) should be multiplied with climate data according to priorities 2-4. You can add these materials individually similar to how other materials are added. However, one way to facilitate the process is to use the grouping function to create constructions. This is explained further in the article Group Materials As Constructions.

Classification systems

In the tool, you can use two separate classification systems: BSAB83 and the building part classification according to Level(s). Datapoints will recieve default choices for these based on in which building part section you add them but by clicking on the classifications a dropwdown is open where you can change the classification as required. Both classification systems can be exported in the Excel results report. In the Graphs section, you can choose which classification system you want to use in the graphs. Read more in the section "Results and Reporting" below.

Transportation distance and profile

Default values for transportation are based on Boverket data but you can update the transportation distance or transportation profile if you wish.

Service life

Materials will have a default service life when added to the project, shown in the "Service life" column. Adjust these if needed.

Wastage

Wastage on the building site refers to the proportion of construction materials that are delivered to the site but not incorporated into the finished building. Materials will have a defualt values based on values from the Boverket database but the wastage percentage can be adjusted as needed in the Wastage column.

Repair

If a product or material is expected to be subject to annual repairs, set the percentage of the product that shall be replaced as a consequence of such repairs. This value is set as the annual rate of repair, and thus the total rate of repair over the lifetime of the building is the annual repair rate times the assessment period. For example, if one window in ten breaks every five years, the appropriate annual repair rate would be 2 %. This value can be adjusted as needed.

End-of-Life Process

Materials will have a default end-of-life process based on the choice in the LCA parameters of the project. They are shown in the EOL Process column and can be adjusted as needed. More information can be found in the articles End-of-Life Scenarios for Construction Products and Advanced End of Life Modelling Options.

Reused and Locally Reused Materials

When checking the box "Reused material", material manufacturing (A1-A3) and material wastage-related installation (A5) impacts are left out for the material, as these life cycle stages are accounted for in the scope of the building the materials were reclaimed from. If the reused materials have a service life less than the calculation period of the assessment, material replacements are calculated as usual and are always considered as new materials.

When checking the box "Locally reused", impacts related to the initial material transportation (A4) will be ignored. Impacts are still accounted for transportation of replacements and waste treatment.

If you wish to exclude both A1-A3 and A5, and A4 for a material, both check-boxes should be marked for the material in question.

Refurbishment

In the tool, replacements or refurbishment of materials are based on the service life of the individual product or material and the service life of the building. Based on this, the number of replacements over the building's lifecycle is calculated.

Check the Refurbishment box if the material is used for renovation or refurbishment purposes to place emissions from replacements in module B5. If the box is left unchecked, emissions from replacements will be allocated to module B4.

Please note that Materials added to the section "Foundations and substructure" are assumed not to be replaced or refurbished.

Simplified LCE

As mentioned above in the section "Data Scope", when data from Simplified LCE calculations are used, a top-up of 25 % should be applied to that material. When you check this box, the top-up of 25 % will be applied to the row.

Since a 25 % top-up should also be applied when Proxy-EPDs are used, the same check-box can be used also for these material rows to get the same calculation.

Change menu

The last column includes the "Change" menu. This allows you to Copy, Split, Replace, Lock or Delete resources. Read more here: Replace or Split Material Choices.

In this query, annual data for electricity, fuel, district heating, district cooling and exported energy occuring during the use phase can be added.

As per the NollCO2 Manual (Sweden Green Building Council, 2024), instructions are the following:

Electricity: National electricity mix data from Boverket should be used.

District Heating: The boundary for the LCA data used is local district heating. This may be replaced with national values if local values are unavailable. The data should be location-based. Market-based data may not be used. Local values according to the methodology of VMK (Värmemarknadskommittén), published by Energiföretagen are to be used. The most recently published data for the year in which the calculation is performed must be used. EPDs for district heating networks are not approved for use.

Below are examples of distric heating data from Energiföretagen in One Click LCA:

District Cooling: The data used is location-based, or may be replaced with national values if local values are unavailable. EPDs from the local district cooling network may be used if such is available. In that case, data from the local network that connects to the building must be used.

Other Energy: For other types of energy, such as biofuels, use data from Boverket.

Self-produced energy: The climate impact of technical equipment for renewable energy production on the property is reported in A1–A5. However, it should be reported separately and should not be included in the limit value.

In this query, data for annual water consumption (B7) can be added. The NollCO2 manual specifies datapoints for upstream and downstream climate impacts from water and these can be found in the tool with the names "Water upstream climate impact, Sweden" and "Water downstream climate impact, Sweden".

In this query, data related to impacts on the construction site can be added.

You can find scenario data in the "construction site scenarios" section.

Other sections such as deconstruction, energy use on the site, materials use on the site, construction site water use or additional trips for the transport to the construction site, are also available.

In this query, you can add data for refrigerants or carbonisation of concrete if you are including these in your calculation.

In this query, annual activities related to Maintenance are added. Data can be added in the different sections.

Maintenance scenarios based on data from the report "Anvisning för LCA-beräkning av byggprojekt" can be found in section "1. Maintenance scenarios" and sub-section "Building level maintenance scenario".

In the NollCO2 tool, the future scenarios are based on the decarbonisation scenarios specified in the NollCO2 manual. You should specify the year when the building is taken into use/when the calculation is submitted in the dropdown menus in sections "1. General Future Scenarios" and "2. Energy Future Scenarios".

Section 1. General Future Scenarios will apply to future emissions in B1-B5, B7 and C1-C4.

Section 2. Energy Future Scenarios will apply to future emissions in B6.

Here you should enter the calculation period for the building. In NollCO2, this should be set to 50 years.

Set the building area. Use the datapoint "Bruttoareal (BTA), Sweden".

In this section, the results page will be explained, including result tables, graphs and how to export results in different formats. The Results page is also explained in the article: Navigate the Results Page.

In the Results table, the results are presented per life cycle module with the unit kg CO2e/m2 Gross Floor Area. You can download the table by clicking on "Download Results Summary". Some sections can be expanded by clicking on the "+" sign next to the life cycle module. If you want to see a breakdown per resource within each life cycle, click on "Details".

By clicking in the "More actions" button, you can download reports such as the One Click LCA results report or a Word report. You can also download the data sources used, send the data to another user or export all EPDs used in the project as pdf files if you want to save these.

On the Results page, you can find the completeness and plausibility checker as in most One Click LCA tools. More information about this can be found in the articles LCA Checker, Ensuring LCA Quality and AI Plausibility Checker.

The "Most Contributing Materials" list in One Click LCA helps you pinpoint and reduce your project's environmental impact. By highlighting the top 25 materials with the highest Global Warming Potential in A1-A3, it allows you to prioritize your efforts on finding lower-emission alternatives. With an Expert license, you gain access to material benchmarks and alternative suggestions, further optimizing your material selection for a more sustainable project.

In the Graphs section, you can choose between different types of graphs. You can also choose which classification system to use. The classification systems available in the NollCO2 tool are BSAB, Building parts (according to Level(s)) or your private Company Classification.

You can also download the graphs in different formats, or view the data tables of the graphs.

When submitting a NollCO2 calculation to SGBC for certification, the calculation is reviewed by SGBC. If agreed between the project owner and SGBC, One Click LCA can provide the reviewer from SGBC access to the project directly in the software by adding a SGBC license and the reviewer to the project. If you need help with this, please contact the One Click LCA support team.

If you have questions or feedback on the tool, don't hesitate to contact our support team.