Retrofitting Can Be Defined As Changing, Modifying Certain Parts, Aspects of a Structure With New or Better Parts Which Will Prove to Be Beneficial For the User of the Building Building Itself. In A Similar Sense, Green Retrofit Can Be Done By Changing Certain Parts of Building That Damage The Environment and Changing It With Sustainable Alternatives Which Will Increase the Life of the Building And Reduce the Life-Cycle Cost of the Same. This Can Also Be Achieved By Undertaking Many Practices Which Not Only Enable Conservation the Natural Resources But Also Enable Us to Enhance the Environment And Contribute Towards Adopting Encouraging Sustainable Construction Practices Green Materials Recycled Materials For Which the Cost For Construction and Installation Have Also Been Measured. This Concept Of Retrofitting Benefits from Making Use Renewable Sources of Energy and Making It the Primary Source, Such As the Making Use of Sunlight and Converting It into Electricity. Costs and Benefits of Such Retrofit, Comparisons Between the Two Systems Are Used In the Cost-Benefit Study.