Concrete is the most cost-effective material for building an insulated floor slab, Baden Brown said.
"We want to reduce the amount of carbon that we are emitting. That's the main purpose of a passive house. This is just another step to say we want to be a bit more responsible."
On Tuesday
the concrete was mixed by Allied Concrete and looked the same as any, Penn said. He was confident it would be as strong as any, and said it gained strength faster.
The cost will be about the same, or a few per cent more expensive, Bazoeva said.
The D5 Green additive was pioneered by her Russian father, Dr Oleg Bazoev. She brought it to New Zealand two years ago, where it has been tested by WSP, formerly Opus.
D5 Green is a mixture of volcanic ash and other naturally occurring minerals, with a chemical plasticiser. It creates a tougher crystal in the concrete.
Bazoeva is importing the substance from Russia, but hopes to make it in New Zealand and export it to Australia.
It can be used to substitute for 16 to 33 per cent of the cement in concrete, and she is hoping to move that up to 50 per cent.
The Neocrete website will have a calculator people can use to find out how much carbon they have avoided emitting.
Starting this month, Neocrete has a Callaghan Innovation Grant to research its further uses.
Reducing emissions from concrete is important because it is such a common building material and making it accounts for 8 per cent of the world's carbon emissions, Bazoeva said.
The D5 Green product has been used extensively in Russia and Korea, but mainly for dams, bridges and the foundations of high rise buildings.
A pour for an eHaus in Nelson in August was its first commercial use in New Zealand.
Most of the interest in New Zealand so far has been from builders wanting to reduce their carbon footprint.
