Utility bill savings vary by existing system limitations. If your system is over 10 years old, newer Energy Star rated equipment will likely save well over $100 on energy bills. There are other system considerations that can also improve efficiency and lower energy costs. Keeping filters clean, making sure ducts do not have air leaks so they provide full flow to vents, even insulating ducts can have a profound effect on energy savings. Other air leaks like windows and doors can have an effect on system performance and comfort levels leading to an increase in energy usage. When you consider the environment your HVAC system operates in, fixing leaks, drawing curtains on hot summer days, closing vents in un-used areas, can all contribute to lower bills and better system performance and comfort.