Retrofitting refers to the process of upgrading or modifying existing structures, systems, or equipment to improve their performance or make them more energy-efficient. This process is typically performed in older buildings or homes to bring them up to current standards and enhance their energy efficiency1. Here are some common methods and techniques used in retrofitting:

1. Adding New Shear Walls: Shear walls are structural elements that resist lateral forces (such as wind or seismic loads). Retrofitting may involve adding new shear walls to improve the building’s stability and safety.
2. Steel Bracing: Steel braces can be added to existing structures to enhance their resistance to lateral loads. These braces help prevent excessive swaying during earthquakes or strong winds.
3. Jacketing: In jacketing, a new layer of material (such as reinforced concrete or steel) is applied to the existing structure. This strengthens the building and improves its load-bearing capacity.
4. Epoxy Injection: Epoxy injection is used to repair cracks in concrete structures. By injecting epoxy resin into cracks, the structural integrity of the building can be restored.
5. Energy Efficiency Improvements: Retrofitting can also focus on energy efficiency. Upgrading insulation, windows, HVAC systems, and lighting can reduce energy consumption and lower utility bills.

Remember that retrofitting plays a crucial role in climate change mitigation, circular economy practices, and making existing buildings more resilient to extreme weather events1. If you have any specific questions or need further details, feel free to ask!