Old city courtyards are crucial elements of Beijing’s ancient capital. However, existing ones face heating problems. This study focuses on renovated and original-style courtyards. By employing ENVI-met and DeST software, we comprehensively analyzed the courtyard’s thermal environment, ventilation, indoor conditions, and energy consumption. Findings reveal that both types have thermal discomfort. Original courtyards are colder in winter and hotter in summer due to wind and radiation. They possess better ventilation but a higher winter heating load. Both require winter heating, with the original ones having a larger unit area load because of envelope heat loss and ventilation differences. Their direct electric heating consumptions, 187.6 kWh/m² and 229.6 kWh/m², respectively, surpass ordinary residences. This study defines issues for future green and low-carbon courtyard work.