Building energy-consumption status worldwide and the state-of-the-art technologies for zero-energy buildings during the past decade

Energy consumption has dramatically increased in buildings over the past decade due to population growth, more time spent indoors, increased demand for building functions and indoor environmental quality, and global climate change. Building energy use currently accounts for over 40% of total primary energy consumption in the U.S. and E.U. Nevertheless, significant energy savings can be achieved in buildings if they are properly designed, constructed and operated. For this reason, building energy efficiency can provide key solutions to energy shortages, carbon emissions and their serious threat to our living environment. This paper offers a brief overview of building energy-consumption situations, relevant energy-saving approaches, and the influence of global climate change. Building energy-consumption situations based on data derived from international energy reports are initially compared between the U.S., China and the E.U. Both similarities and differences are found in aspects of building energy end-uses and final energy fuel-types among these top three building energy consumers. We then introduce the current concept of the zero-energy building (ZEB). State-of-the-art approaches for ZEB technologies are summarized in three categories: passive energy-saving technologies, energy-efficient building service systems and renewable energy production technologies. The feasibility of these technologies is reviewed. In addition, we briefly discuss the influence of global climate change on the evolution of building energy use in the future. We find that climate change significantly impacts building energy performance, particularly in space heating and cooling. Improvements on building envelope and ventilation can play an important role in reducing space heating and cooling consumption levels. We also provide some suggestions for further developing ZEBs.