Concrete is one of the most used materials and is a significant part of current construction due to the material’s good properties. However, there is also something very negative about concrete, the emissions at production stage. The purpose of this study is to examine if the traditional concrete foundation method can be replaced with an alternative foundation method that contain less concrete and therefore decrease the climate impact. The two alternative foundation methods are the Koljern-foundation and the Klara-foundation. A two-story example building was used to compare the foundation methods. To reach the result of the study, different methods of calculation were performed. The climate impact of the foundations was calculated with the calculation software BM 1.0 and the carrying capacity were calculated with EPS PEPS. The result of the study shows that the alternative foundation methods have similar properties to the traditional concrete foundation and that they decrease the climate impact by 10% for the Koljern-foundation and 60% for the Klara-foundation in relation to the traditional concrete foundation.  The conclusion of the study is that both the alternative foundation methods can be used as replacement for the traditional concrete foundation method for two story buildings, and that the alternative foundation methods decrease the climate impact.

Concrete is widely used in modern construction, particularly for building foundations. However, the materials included in concrete constructions have a significant negative impact on the environment. To mitigate this, the construction industry must explore more environmentally friendly alternatives. This study focuses on a relatively new technique called the Koljern foundation, which replaces traditional reinforced concrete slabs with a combination of cellular glass and lightweight steel beams. The cellular glass used in this technique is made up of approximately 60% recycled glass and possesses excellent insulation and strength properties. The report compares the cost and environmental impact of the traditional concrete slab with the Koljern foundation. Other factors considered in this study includes construction time, waste, and potential for reuse. A case study was conducted on a preschool building in Gunsta, serving as a reference for the analysis. Climate and cost calculations were performed using Bidcon software, along with manual calculations. The Gunsta preschool utilized green concrete for its foundation slab, and this is also included in the comparison to provide a broader perspective. The results demonstrate that opting for a Koljern foundation reduces environmental impact by 50% compared to a traditional concrete foundation, although costs increase by 103%. When compared to green concrete, the Koljern foundation has a nearly 42% lower carbon footprint but incurs a cost increase of 101%. Green concrete has a nearly 13% lower carbon footprint compared to traditional concrete. The price difference between green and traditional concrete is only 1%, with green concrete being the more expensive option. Furthermore, the Koljern foundation generates minimal waste due to the prefabrication of Koljern elements by Evia AB. In conclusion, the result of the study shows that a slab-on-grade foundation using the Koljern technique can be a possible alternative to the traditional concrete solution, depending on the specific project's objectives and goals. Despite higher costs, the Koljern foundation greatly reduces environmental impact, construction time, and enables high reusability.