eHaus brand adopts low-emissions D5 Green concrete additive

Contractors pour a house floor using concrete with the D5 Green additive. Photo / Supplied

Whanganui builders have used a concrete additive new to the market to pour the 37sq m concrete floor for an energy-efficient passive house in Westmere.

The additive D5 Green, marketed by Neocrete, replaced 33 per cent of the cement in the pour. Making a tonne of cement in New Zealand requires the emission of 800kg of carbon dioxide.

The use of D5 Green as an alternative for some of that cement avoided 3.1 tonnes of carbon being emitted, Neocrete managing director Zarina Bazoeva said.

The house is being built by Simon Penn, the licence holder for the eHaus brand in the Whanganui region. The brand, owned by Jon and Lisa Iliffe and Glenda and Baden Brown, delivers energy-efficient homes known as passive houses.

eHaus will be using the additive in concrete for all future builds by licence holders all over New Zealand.

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.