Challenges in, and the development of, building energy saving techniques, illustrated with the example of an air source heat pump

Energy consumption of building takes a big proportion among all consumers, which promotes the research topics around building energy saving very hot. However, it is very hard and impossible to introduce all current trends in such a big field in an article. Nearly all branches and small crossing fields have been reviewed in the open literature. Considering the two aforementioned reasons, the research trends in building and energy saving are shortly reviewed here, taking the topic of air source heat pump as a typical example. Firstly, the background of building energy saving and its highlights over the past 50 years are divided and introduced, supported with published data of journal articles in Elsevier. It is expected to show the reader a whole map about this topic. This is followed by the reviews on building materials, consisting of thermal insulation material and phase change materials, and on building equipment, from building automation system to heating, ventilation and air-conditioning system, and then to detailed air parameter control strategy. Thirdly, it is reached to the air source heat pump, with trends around system and frosting/defrosting problem separately reviewed. As concluded, both of fundamental mechanism researches and application technology solutions are important. Research trends in this field are moving towards intelligent, multidimensional, and interdisciplinary.