A Critical Review on Concept and Fundamentals of Net-Zero Energy Buildings

In the last decades, the fossil fuel depletion has accelerated massively, leading to emit a huge volume of greenhouse gasses into the atmosphere daily and the earth temperature increase. New policies all around the world are devised to reduce the consumption of nonrenewable energy sources. Renewable sources of energy (RES), like wind and solar, are considered to provide future energy of the mankind activities. Future Smart Grid, which includes a lot of new technologies and standards, is the best matter to have RES vastly in utilization. Undeniably this extensive change of the electricity grid, requires sufficient research and investigation besides to excessive governmental investment. On the other side, the first steps for implementing a smart grid or employing RES should be practical and less expensive. As a result, household sector, and specifically buildings that are blamed for consuming about 40 percent of whole global energy seems to be a good point to start. In the next generation of buildings, the annual energy consumption is equal to generated on-site renewable energy and because of that, they are called Net-Zero Energy Building (NZEB). NZEB could be grid-connected or off-grid which suggests the best choice for electrifying remote isolate areas. In this paper, a review on new definitions and advances in the field of NZEB is presented.