Fresh reports on the unusual calamity that also killed a Thai man indicate that New Zealander Michael Coppins, 51, was gassed while trying to rescue others.
In the aftermath of the early morning crisis inside a three-storey ventilator chimney in southern Thailand, Mr Coppins' brother Phil told Radio New Zealand that his brother would always act first and think of the consequences later.
News reports described ''chaotic scenes'' yesterday at the eco-friendly site where the tragedy occurred, Plan Eco Energy Co, being erected next to Para Veneer 2002 Co in Thailand's Trang province.
Mr Coppins and his colleague tried to save a couple who passed out in a three-metre wide chimney after inhaling gas. The couple were rescued but Mr Coppins and Rod Singkham, 31, sacrificed their lives.
In New Zealand, Phil Coppins had first learned of what happened when he was contacted by one of his brother's colleagues.
''They hadn't mentioned at this stage that he was going to rescue anybody - he'd gone into a restricted are and breathed in some pretty deadly gas and had been taken into hospital in a pretty bad way, and had a pretty low prognosis that he would survive,'' he told a radio station.
Only later did it become clear that Michael had died.
The conditions Coppins was working under worry his brother. The power plant had to be completed and they were struggling to meet the deadline to get the plant operational, Phil Coppins said.
''It sounds like they had done some pretty long hours,'' he said. ''The fact that they were there at midnight and on a Sunday tells a story of what was needed to be done.
''Being the country it was in [Thailand], I think we are going to struggle to get to the bottom of what has happened,'' Mr Coppins' brother said.
''That Mike's passed away in this manner is no surprise to us really - that he has saved other people with no thought to his own cost. It is pretty hard to put that proud emotion above the heartbroken one.''
Plan Creations has begun building a biomass plant using leftover rubber sawdust and tree roots to fuel a five-megawatt power generator to supply its electricity needs and sell the excess to the local electricity authority.
Mr Coppins had recently returned to New Zealand for nine weeks for the first time in about five years, local newspapers reported.
''We had a really good catch up, so we're pretty grateful that we got that time with him,'' Phil Coppins said.
In a statement, the family said Michael had gone to Malaysia in 1993 with a church team, where he helped to repair a long house for the Eban people of Sarawak.
He remained in Malaysia and married, fathering three children. Two are teenage girls, the third is three years old, according to NZ media.
His work in Thailand was for Kuala Lumpur-based Renewable Energy Plus. Renewable energy was a cause he was passionate about, believing he would make a positive change for the future of the environment.
Police are still investigating the full circumstances surrounding the gas leak and the deaths of the two men.
Mr Coppins' body, now at a hospital in Songkhla province, will be transported to Malaysia or New Zealand.