Towards net zero energy building: The application potential and adaptability of photovoltaic-thermoelectric-battery wall system

Net zero energy buildings (NZEBs) are the future direction of architectures as well as the guideline to counter-act with energy issues. In this study, we proposed a new concept of “double zero” for building envelope, in which the “first zero” means zero heat gain/heat loss through building envelopes and the “second zero” means net zero energy consumption to fulfill the “first zero”. By setting the goal of “double zero”, a new compound building envelope system was proposed with integration of photovoltaic (PV), thermoelectric (TE) modules, and battery system with envelope structure. The “first zero” is realized by TE cooling/heating using power from PV or battery to control the inward heat flux. The “second zero” is made by model predictive control (MPC) of power flow and battery capacity optimization. A system model was established with combination of analytical and numerical methods, which was validated against experimental data in both summer and winter conditions. The study results suggested that the system is highly adaptive to different climate zones for realizing the “first zero” even with non-optimized configurations. It was found that the system can realize 72–92% energy saving in cold region, 88–100% in mixed zone, and totally 100% in cooling dominant zone, compared with a massive wall as a reference. The net energy consumption maps are produced based on massive simulations and the zero energy line can be identified as an important guideline for implementing “double zero” in building envelopes under different operation years.