The utility model discloses a building and an energy system for the building; the building comprises a top portion and side walls positioned on an outer side of the building and being irradiated by the sun, and a floor paved in the building; the energy system comprises the following elements: solar panels respectively arranged on the top portion of the side walls of the building; piezoelectric ceramic sheets embedded in the floor; an energy storage device connected with the solar panels and the piezoelectric ceramic sheets, and used for storing power energy respectively generated by the solar panels and the piezoelectric ceramic sheets. In the prior art, a building, like a classroom, has a low utilization rate for solar energy, and mechanical energy generated by motions of people in the building is not utilized; the energy system of the utility model can solve the said technical problems, so clean energy is fully utilized, environment pollution is reduced, low carbon environment protection is realized, and science and technology intension of the classroom is improved.