1. Directive 2010/31/EU of the European parliament and of the council on the energy performance of buildings. Off. J. Eur. Union 153, 13–35
2. REN21, Renewables 2017 – Global status report, ISBN 978-3-9818107-6-9
3. M. Kummu, O. Varis, The world by latitudes: a global analysis of human population, development level and environment across the north-south axis over the past half century. Appl. Geogr. 31, 495–507 (2010)
4. By Cmglee – Own work, CC BY-SA 3.0.
https://commons.wikimedia.org/w/index.php?curid=30611313
5. M. Iqbal, An introduction to solar radiation (Academic Press, Toronto, 1983)