Over half of the population of the world live in
urban areas. This means that efforts to meet human
development goals and sustain economic growth
must be concentrated in cities. However, the pursuit
of more prosperous, inclusive and sustainable urban
development is complicated by climate change, which
multiplies existing environmental risks, undermines the
effectiveness of existing infrastructure, and creates new
resource constraints.
In this paper, we conclusively demonstrate that there

Green building is an important measure to deal with energy and environment problems in the construction sector of the world. In this study, knowledge mapping analysis is used, and 3,060 articles are selected for further study (1900–2019). Based on CiteSpace (5.3.R4 SE 64-bit), the knowledge base, hot topics and research trends of green-building-related research are presented. The key highlights of the overall analysis results are: (1) Research on green buildings has received more extensive attention in the 21st century.

Heat pumps are relatively simple appliances. They share similar components to refrigerators and air conditioners and effectively move an external source of heat to where it is needed, such as in buildings for heating or the production of hot water. Their key value is efficiency; for each unit of electricity consumed to operate them, they produce multiple units of usable heat. Because of this, they require much less energy input for a similar heating outcome compared to combustion technologies, making them naturally cleaner and generally cost effective to run.