Building retrofitting towards net zero energy: A review.

• A comprehensive review on building retrofit measures towards net-zero energy buildings is conducted. • Climate and occupant activities of fifty case studies are surveyed. • Passive, active, and renewable building energy retrofit measures are discussed. • The assessment methodology of retrofit measure selection is detailed. • Future studies are proposed to fully explore the potential of net zero energy buildings as sustainable structures. High energy consumption is a critical problem that governments are trying to overcome. The concept of Net Zero Energy Building (NZEB) has recently emerged as one of the solutions that can help address this problem, reduce pollution impacts, and mitigate the effects of global warming. The present paper discusses the current research on building energy retrofitting through a comprehensive review of more than fifty case studies, highlighting the ones that aimed to reach a NZEB. The passive, active, and renewable retrofit measures used are discussed. The assessment methodology for choosing the retrofit measures are classified into multi-criteria and optimization approaches and the available simulation tools and algorithms are detailed. The review also indicates that photovoltaic panels are used in retrofitting in all case studies to achieve NZEB, with the tilt angles of photovoltaic panels and solar collectors steeper in colder climates. It is noted that retrofitted residential NZEB buildings exhibit the lowest total energy consumption across all climate types when compared to other NZEB types, such as educational, business, and institutional buildings. Needed research directions include taking into account climate change in the modeling, and the use of bio-based materials to further reduce the building carbon footprint. [ABSTRACT FROM AUTHOR]