Frequently Asked Questions (FAQs)

Is Carbon Checker a replacement for SBEM?

No. Carbon Checker is a replacement for iSBEM, the default interface provided with SBEM. Carbon Checker incorporates an SBEM calculation engine but this is but users do not see this and do not need to run iSBEM separately.

What version of SBEM does Carbon Checker use?

The current version of SBEM is 5.2.d and this is the version of SBEM built into the current Carbon Checker software (1.8). Carbon Checker is approved SBEM interface software, and it is a requirement for approval that if any changes are made to SBEM, the interface software is updated to reflect those changes within three months.

Where is the .nct file?

Carbon Checker does not have an .nct file. The .nct file is produced by iSBEM and is where iSBEM stores all the information for a project. Carbon Checker stores information for a project in a completely different way, and stores its data in a file with the extension .ccz. Regardless of whether you are using iSBEM or Carbon Checker, the interface passes to SBEM the information that SBEM requires to perform the calculation.

Where is my XML file for EPC lodgement?

When running a calculation, Carbon Checker creates a folder (with the same name as the project file) where all the output files will be written.

For example, if your project file is called…


… an output folder will be created called…


… and all the output files will be created in here. This helps keep things neatly organised.

One of the output files is the .XML file which needs to be lodged if you are producing an EPC. The mechanism for lodgement should be exactly the same regardless of whether you are using iSBEM or Carbon Checker (but you should check with you accreditation scheme.) Before running a calculation, Carbon Checker deletes any existing output files from this output folder.

What are all these “Q50-INF” warnings that the software raises?

Carbon Checker passes the detailed information about the building to SBEM, and SBEM proceeds from there. One of the things SBEM does is to check that data values are within expected ranges. If the values are outside the expected range, SBEM includes an item in an error report. Carbon Checker displays this report to you so you can see any issues that SBEM has identified.

These checks are outside our control, and they often raise warnings that can be safely ignored. For example, any air permeability value greater than 10m3/( will raise a warning, even though a value of 25 is an accepted sensible default for existing buildings. Also, in zones without any HVAC, warnings will be raised concerning the efficiency of the (non-existent) HVAC equipment. The same anomalies will arise if using iSBEM, but you might not notice them if you don’t look at the warnings file produced by SBEM.

If the item is described as a “warning”, but you’re happy that the item is indeed OK, it’s fine to continue.