I bought my house new. Forty years later it is old. Even with regular maintenance and repairs, things get worn out and need replacement. My original windows are single pane. Ouch! That means that they were not as energy efficient as modern double and triple ones are. Good windows and doors really are an investment.
The cost for heating and air conditioning an all electric home is a monthly ever-rising given expense. My old windows are a money pit. The labor and materials to change windows is a one time cost that is well worth it in the long run. The decision would be much simpler and cost effective if the house had been built with ducting and venting.