This study presents a summary of green building research through a bibliometric approach. A total of 2980 articles published in 2000–2016 were reviewed and analyzed. The results indicated that green building research had been concentrated on the subject categories of engineering, environmental sciences & ecology, and construction & building technology, and the keywords ‘building envelope’ and ‘living wall’ obtained citation bursts in the recent years.

This study presents three cost-optimal calculations. The overall aim is to provide a deeper analysis and to provide additional guidance on how to properly implement the cost-optimality methodology in Member States. Without proper guidance and lessons from exemplary case studies using realistic input data (reflecting the likely future development), there is a risk that the cost-optimal methodology may be implemented at suboptimal levels.

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.