The construction sector being a major contributor to global CO2 emissions, the integration of high-quality, precise data in early design phases becomes crucial for effective sustainability measures. This study focuses on the variations in data quality at different Levels of Detail (LOD) and their impact on the accuracy of climate impact assessments. Utilizing a case study approach, the research investigates the dynamic between LOD specifications, and the quality of data provided, demonstrating that early-stage LODs often exhibit more reliable data. The findings suggest that improving data quality in BIM and IFC can significantly refine sustainability assessments and project outcomes, supporting the construction industry's move towards rapid decarbonization. Through the meticulous analysis of European standards and regulations, this work contributes to the strategic implementation of sustainability practices in building design and construction, advocating for enhanced data management protocols to better align with environmental and regulatory demands.