Cost optimal investment in energy efficiency measures and energy supply system in a neighbourhood in NorwayHarald Taxt Walnum, Marius Bagle, Åse Lekang Sørensen and Selamawit Mamo FufaE3S Web Conf., 246 (2021) 05005DOI: https://doi.org/10.1051/e3sconf/202124605005