As the stock of aging buildings increases, renovation is an alternative to demolition and new construction, reducing environmental impacts and material waste. Effective retrofitting should enhance thermal comfort, minimize energy demand, particularly for heating, cooling, and ventilation, and optimize material use. Building on our previous study of Norwegian residential archetypes, we evaluate three retrofit strategies using a bottom-up, physics-based approach. Our findings show that even minimal interventions, such as window replacement, significantly reduce heating demand. However, a more comprehensive retrofit—including external wall and roof insulation, window and door replacement, and balanced ventilation—achieves greater energy savings while maintaining indoor comfort.