One of the gaps in green building research in Euro-Mediterranean countries is the assessment of Leadership in Energy and Environmental Design (LEED)-certified projects in the context of the LEED rating system’s ongoing transition from a prescriptive to a performance-based approach. This study evaluates LEED certification strategies by analyzing the causal relationships between five independent LEED performance indicators and the overall LEED score for LEED for Existing Office Buildings version 4.1 (LEED-EB v4.1) gold-certified office projects in Sweden, Italy, Israel, Spain, Germany, and Ireland using simple linear regression. Linear regression showed that each of the six above-mentioned countries demonstrated a unique LEED certification strategy for LEED-EB v4.1 gold-certified office projects. Linear regression revealed, for the first time in the literature, that the causal relationship between the independent indicator “energy” and the dependent indicator overall LEED score was statistically insignificant (R2 = 0.04 and p = 0.359; R2 = 0.13 and p = 0.112, respectively) in LEED-EB v4.1 gold-certified office projects in Germany and Ireland. However, in Sweden, Italy, Israel and Spain, this relationship was statistically significant (R2 = 0.38, 0.46, 0.53 and 0.40 at p < 0.001 in all cases, respectively).