Review and analysis of current solutions and trends for zero energy building (ZEB) thermal systems

Building heating and cooling systems provide the greatest potential for energy consumption reduction in the U.S. As such, these systems have gained immense interest for decades, garnering an extensive range of solutions and strategies to provide energy-efficient thermal conditioning of the indoor environment. This study reviews and discusses this large breadth of research in combination with past and current industry trends to discover future zero-energy building thermal systems, subsystems, and control strategies in support of the Zero Energy Buildings initiative. The reviewed articles were selected from top research and industry journals, with a focus on review and high-level articles. It is clear from the articles that radiant, water-based systems are superior to convective, air-based thermal conditioning, and that passive strategies offer an immense opportunity for energy demand reduction of thermal systems. Additionally, future thermal systems must provide onsite TES in support of either renewable energy or passive strategies. Numerous theoretical gaps were discovered in the literature, mostly in the control strategies of different systems. From these gaps, opportunities are revealed that offer energy savings and solutions to large, systemic challenges. These include a nested hierarchy control structure for dual systems, short-term shallow earth TES, concrete collectors and radiators, and a ventilation system that can drive a generator for energy recovery. Taken together, these strategies and systems piece together a future building thermal system.