After spending years chipping away at the challenge of how to reduce the construction industry’s waste and carbon emissions, a local builder believes he’s well on his way to cracking the code.
Based in Greytown, Nicholas Keenan has been trialling a new building product made from hempcrete, a bio-composite construction material.
Hempcrete is made from ‘hemp hurd’ [the dried, inner part of the hemp plant stalk], a binder, and water, and has been raved about by those in the building industry for its clean and green characteristics.
Keenan said he was introduced to hempcrete by a friend a few years ago.
“I said, ‘It sounds a little too good to be true, and I don’t believe it’,” Keenan recalled.
“So I went off and did my own research, read a lot of university papers.
“I found that it’s actually a viable product, and it’s better than anything on the market.”
After intensive trial and error, Keenan has created a “modular housing panel system” – the first of its kind to be developed in New Zealand.
Each unit of roof or wall is pre-made in his Greytown factory and can be transported and slotted together on-site.
“It’s like Lego,” Keenan said.
“They just get picked up with a crane, moved on site and put together. Then all you need to do is slide in the windows and install trims.”
Each panel is made using a timber frame, with the hempcrete solution moulded inside and a lime render applied internally and externally.
Working with the common dimensions used in the building industry, Keenan said the idea behind the modular system is that the customer will be able to choose the design.
“They’re interchangeable modules, so you can swap one part out for another if you want the window or door facing somewhere else.”
Having conducted multiple tests on hempcrete resilience, Keenan said he has been amazed at the results.
“The PH levels are so high, it can’t grow mould. I submerged it for six months, and nothing grew,” Keenan said.
“It’s also fireproof – I ran experiments to try and burn it, and the panels won’t catch on fire.”
Keenan orders the hemp hurd from CP Wool in Christchurch, and the timber frames from JNL, and said the majority of his other materials are sourced in New Zealand too.
“Local distribution is important to me because it reduces that carbon footprint,” Keenan said.
“If I were importing everything I needed for this, it would defeat the purpose.”
The Hemp Building Association NZ states that the construction industry globally is responsible for 25 per cent all carbon emissions.
As hempcrete absorbs a significant amount of carbon dioxide when it grows, and again when it’s combined with its binder, it’s viewed as a miraculous ‘carbon sink’ – properties that Keenan said prompted his obsession with the product.
“One of the major issues we have in the building industry is the waste.
“We’re building bespoke houses, so you’re losing about thirty per cent from the majority of materials that turn up on site,” Keenan said.
“With this, you have the CO2 sequestration in growing the hemp plant, and it also sucks CO2 out of the atmosphere while it’s curing.”
Having been working solo on his ambitious endeavour up to this point, Keenan is now looking forward to finding investors and taking the next steps forward with the business.
