**6. Conclusions**

The overall design of LCC in the demonstration series was successful, as both mixes reached the requested strength class despite lacking 9.8 and 5.3% of the REF mix. But the second intention to design concrete for freeze-thaw exposure was not successful, as the mixes exceeded the scaling limit level despite showing high chloride migration resistivity. Example: LCC mixes had a higher aggregate share, which allowed for cement reduction and only partial replacement by SCM. EPD is for two particular concrete productions located in Norway, and even with that, we can see differences in EPD values. Therefore, the same mix design produced in a different location will have a different EPD value/carbon footprint per 1 m3 of concrete. The difference between the REF mix produced in two different concrete plants was 12.6%, according to the demonstration series used in this article. The LCC1 carbon footprint was reduced by 48.2 and 34.6%, and the carbon footprint of LCC2 was reduced by 46.1 and 51.0% in NB and HGB.

In all classification systems from Norway, Sweden, Iceland, and Finland, the REF mix complied with the criteria for industry reference, and when produced in HGB, it was even classified as the first level of LCC according to SE:SCI, IS:LCCxxx, and FI:LC class. The LCC mixes moved by 2 to 3 classes, which points out that systems are comparable; only the Norwegian is more ambitious, with an extreme class of 130 kg CO2—eqv. per 1 m<sup>3</sup> of concrete. In addition, the Icelandic system has classes down to a value <105 kg CO2 per m<sup>3</sup> of "EcoCrete-Xtreme" and is mainly informative without direct comparison to industry reference. On the contrary, the Swedish system is well developed and clearly describes classes based on exposure classes, but the highest recognized class, "climate improved class 3", is rather conservative, and other classes with a lower carbon footprint might be essential.

**Author Contributions:** I.N.: conceptualization, validation, writing—original draft preparation, funding acquisition. P.P.: methodology, writing—review and editing. A.C.: methodology, writing review and editing. O.H.W.: methodology, writing—review and editing. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Northern Periphery and Arctic programme 2021-2027, Project No. NPA0100039.

**Data Availability Statement:** No new data were created or analyzed in this study. Data sharing is not applicable to this article.

**Acknowledgments:** I would like to acknowledge the Interreg bridging call project ArCorD, within which the first draft of the study took place. The publication cost of this paper was covered by the funds of the Polish National Agency for Academic Exchange (NAWA): "MATBUD'2023—Developing international scientific cooperation in the field of building materials engineering" (BPI/WTP/2021/1/ 00002, MATBUD'2023).

**Conflicts of Interest:** The authors declare no conflict of interest.
