1. The energy performance of buildings Directive (EU) 2018/844 of 30 May 2018.
2. Buildings Performance Institute Europe. 97% of buildings in the EU need to be upgraded. http://bpie.eu/publication/97-of-buildings-in-the-eu-need-to-be-upgraded/
3. European Construction Sector Observatory https://ec.europa.eu/docsroom/documents/24261
4. Buildings Performance Institute Europe. Prefabricated systems for deep energy retrofits of residential buildings. http://bpie.eu/wp-content/uploads/2016/02/Deep-dive-1-Prefab-systems.pdf
5. Kuusk K (2015). Integrated cost-optimal renovation of apartment buildings toward nearly zero-energy buildings. Doctoral thesis, Tallinn University of Technology.