The correct option is B Both A and B
The analysis or survey of energy flow in a system or process (building) for energy conservation is called energy audit. It is done to minimise the energy input into the process which is necessary for the conservation of energy. An energy audit in school and home is done by evaluating the equipments used there. The components of the building like walls, floors, ceilings, windows etc are analysed for the resistance to flow of energy. So, the correct option is D.