Sustainable Retrofits: The balance between energy efficiency and embodied energy

This thesis looks at how to balance energy efficiency with embodied energy in small commercial retrofits, focusing on restaurant buildings. Rather than tearing down older buildings and starting from scratch—something that wipes out all the embodied energy already invested—retrofitting can improve performance while preserving what's already there. Using EnergyPlus for operational energy modeling and the Athena Impact Estimator for embodied energy analysis, this study compares different retrofit scenarios. These include retrofitting one, two, or all three major assemblies (walls, roofs, and floors) to see how each combination affects total emissions over time. The results show that not all retrofits are created equal. Wall retrofits had the biggest positive impact, even outperforming new construction after 10 to 20 years. On the other hand, some upgrades—like floor retrofits—increased cooling demand and overall emissions. The takeaway is that more retrofitting doesn’t always mean better results. The key is knowing which upgrades give you the best return without adding unnecessary embodied carbon.