Where does “nulenergihus” come from?

nulenergihus (Danish) comes from Danish energi, from French énergie, from Latin energīa, from Ancient Greek ἐνέργεια, from Ancient Greek ἐνεργής, from Ancient Greek ἐνεργός, from Ancient Greek ἐν-, from Ancient Greek ἐν — Creates collective nouns, which refer to groups...

nulenergihus (Danish): a zero-energy house a house that has low energy consumption and where the energy is obtained from alternative energy sources (e.g. solar energy or geothermal energy)