There is good number of options to design energy efficient/green buildings. One of the objectives of green building is to conserve the natural resources and substantial energy is consumed in the operation of air conditioning system. In this paper total usage of energy (embodied and operational energy) has been calculated for fire clay bricks and ash blocks building material. Energy and environment indices were calculated and it was found that use of ash block as replacement of fire clay bricks can reduce significantly the heat load, size of air conditioning system and hence contributes towards saving of natural resources and environment.