Northern Ireland-based energy-efficient building firm Sky Developments has gone into administration.
The company is based in Holywood, County Down, and built what was said to be Northern Ireland's first carbon neutral home in 2008.
Sky Developments operated in the residential, commercial and public sector markets, specialising in projects using "modern methods of construction" but called in administrators BDO last week.
North Down Alliance Councillor Andrew Muir described the news as "particularly regrettable".
The first zero-carbon home in Northern Ireland was built at The Esplanade in Holywood. The four-bedroomed home was fitted with an air source heat pump, heat recovery system, solar thermal panels and solar photovoltaic panels. It has been advertised as having no heating bills and minimal electricity bills.
According to the Belfast Telegraph, the builders claimed that Northern Ireland electricity would "owe the homeowner £200 at the end of the year" due to the excess electricity generated through the solar panels.
The building was the first in Northern Ireland to receive an A-rated Energy Performance Certificate.