Achieving net zero energy heating by integrating the building envelope as a thermal battery

Photovoltaic (PV) heating is a promising technology for achieving fossil fuel-free heating and carbon neutrality in the building sector. Cost-effective energy storage plays a critical role in PV heating to solve the temporal mismatch between supply and demand. Herein, we propose the concept of using a building envelope as an active energy-storage device for a PV heating system, thus transforming the building envelope into a thermal battery. Experimental results show that the energy storage capacity of 142 kW h/m2, 2 , which is higher than that of conventional thermal storage systems. We developed a top- down macro performance assessment model to quantify the contribution of a PV heating system using a building envelope as energy storage. By our estimation, the envelope-embedded system can reduce heating-related CO2 2 emissions by 7435.7 tons annually in northern China. Our study provides insights into innovative energy-saving building energy storage systems that can help achieve global carbon neutrality and sustainability.