Net-zero energy building (NZEB) is thought to be the building of choice, but in practice, is also synonym to high investment cost. It is, therefore, very important to investigate if the amount of the additional capital investment could be recouped from the energy saving (or generation). The investigation is particularly meaningful for industrial halls for the great energy saving potential (with respect to the high energy demand) and the ready energy generation possibility (due to favourable building geometry). In this paper, an integrated design approach will take into consideration parameters from the demand side to the generation side. Building energy performance simulation and optimization will be deployed to search for design solutions that are maximized for energy production capability and minimized for additional capital investment.