Jämförande studie av platta på mark och krypgrund med avseende på klimatpåverkan, fuktrisker och energiprestanda.

Sammanfattning

This thesis presents a comparative study of two foundation systems, slab on ground and crawl space, with regard to moisture safety, climate impact and energy performance. The study is based on a reference building in Lekeryd and compares the two foundation solutions under equivalent conditions. The purpose is to investigate which foundation system provides better moisture performance, lower climate impact during the construction phase and more favorable energy performance.The work combines a literature study with calculation based analyses. U values, moisture conditions and energy use were analyzed using Mathcad, Excel and WUFI Plus. The climate impact was assessed through a life cycle assessment limited to modules A1 to A5. The slab on ground was dimensioned to achieve the same U value as the crawl space, which resulted in a total U value of 0.067 𝑊/𝑚2∗ 𝐾. For both systems.The results show that both foundation systems meet their respective moisture requirements under the assumed conditions. The crawl space reached a maximum relative humidity of 72 percent, which is below the critical value of 75 percent. The slab on ground reached approximately 80 percent relative humidity during summer conditions, which places it close to its critical limit. Regarding climate impact, the crawl space including the floor structure resulted in 8439 𝑘𝑔𝐶𝑂2𝑒, while the slab on ground resulted in 14023 𝑘𝑔𝐶𝑂2𝑒. The slab on ground has a slight advantage in energy performance because it does not require continuous fan operation, whereas the crawl space requires approximately 350 kWh per year for mechanical ventilation.Overall the studied crawl space is assessed as the more favorable solution for the reference building, mainly due to its lower climate impact and acceptable moisture performance.