This report describes the Total Energy Model (TEM) 4.0, a novel bottom-up hybrid model designed to forecast data centre energy consumption and evaluate the effect of possible policy interventions on energy use. Moving away from traditional methods that rely on extrapolating equipment sales or data traffic, the TEM focuses on computational capacity and efficiency metrics derived primarily from CPU sales data and standardized Server Efficiency Rating Tool (SERT) performance measurements. It segments the market by data centre type (traditional, cloud, hyperscale, AI) and workload (general compute, AI) across five global regions