Humanity’s Human construction has greatly improved living standards but at a high environmental cost. Buildings are responsible for 37% of global emissions, heavily contributing to climate change. Traditional construction methods cannot sustain long-term living standards, making it essential to upgrade existing buildings. Over 90% of the world’s buildings do not meet net-zero emissions targets, causing significant greenhouse gas emissions. These upgrades are vital as operational emissions from buildings make up 28% of the global annual total, impacting governments, businesses, and financial institutions. Historic buildings (HBs) present a unique challenge due to preservation regulations. Renovating HBs requires balancing energy consumption reduction, carbon emission cuts, and maintaining their cultural and historical values. Retrofitting HBs, while preserving their exterior, is a key research challenge, involving diverse methodologies. Such retrofits are both environmentally necessary and financially beneficial, as inefficient buildings face regulatory penalties that could impact their value. Upgrading buildings to Net-Zero standards is crucial for protecting investments. This study examines the economic benefits of retrofitting using three methods: Life Cycle Assessment (LCA), Life Cycle Costing (LCC), and Cost-Optimal analysis. The findings reveal that retrofitting not only preserves cultural heritage but also proves to be cost-effective in the long term.