A house fit for Grand Designs is under construction in Canberra's inner north.

Once completed, the O'Connor knockdown rebuild will be carbon neutral, termite proof and fire resistant.

And it's made of hemp.

Angela Knock says hemp ticks all the boxes as a building material. ( ABC News: Roxanne Taylor )

When home owner Rowan Woodburn approached designer Angela Knock to draw up plans for a new home, his priority was to slash his energy bills.

"We're not greenies per se," he said.

"But we are conscious of the environmental impact a new build has on the environment and the hip pocket.

"Once we went through the specifications it was a no-brainer."

So what is hempcrete?

Ms Knock suggested the concept of a hemp home, knowing the product had many properties well suited to Canberra's climate.

"What makes hemp really unique is that it offers thermal mass and insulation in the one construction material," she said.

"For Canberra's climate, where we have really cold winters and really hot summers, we need both of those things.

"Hemp ticks all the boxes."

Hempcrete does not contain THC, the active chemical in cannabis. ( ABC Radio Canberra: Hannah Walmsley )

Built using a product called hempcrete, the four-bedroom home will have the capacity to absorb and store up to 18 tonnes of carbon dioxide from the atmosphere.

Hempcrete is made by mixing shredded hemp with water and a lime binder.

"They're all natural materials and when you mix it up it looks a bit like apple crumble topping," Ms Knock said.

The hempcrete is then formed around a timber structural frame and finished with a lime render that bonds with the hemp.

"We're encasing the timber and entombing that structural frame in hemp," Ms Knock explained.

"As it carbonates and the lime sets, it gets harder and harder and produces something very solid.

"It is breathable, so it is also water permeable, which means moisture in the air can escape to the outside and prevent condensation on the windows when there is trapped heat."

The hemp plant's woody stem is shredded, mixed with a lime render and placed inside a timber frame. ( ABC Radio Canberra: Hannah Walmsley )

An alternative to bricks and mortar

The Woodburns are hopeful their decision to use the hemp product could pave the way for others.

"There was quite a bit of labour involved in finding our way, but hemp will so radically reduce heating and cooling loads," Mr Woodburn said.

As part of the process, construction firm Prostyle had workers undertake a training course in working with hempcrete.

And the Woodburns have had the opportunity to get their hands dirty too.

"We had a team of five or six people who helped us with the tamping of the hemp — squashing the hemp into the mixture," Mr Woodburn said.

"It was a fantastic opportunity to be involved in the construction of my own house from day one."