Update from 2021: https://www.sciencedirect.com/science/article/abs/pii/S0167642321000022 https://www.sciencedirect.com/science/article/abs/pii/S01676... Edit

Update from 2021: https://www.sciencedirect.com/science/article/abs/pii/S0167642321000022 https://www.sciencedirect.com/science/article/abs/pii/S01676... Edit to add sci-hub link to full paper: https://sci-hub.st/10.1016/j.scico.2021.102609 https://sci-hub.st/10.1016/j.scico.2021.102609 This appears to be a web page where the authors have posted links to their research, data, updates, etc: https://sites.google.com/view/energy-efficiency-languages/ https://sites.google.com/view/energy-efficiency-languages/