As Director of Hempbuild Sustainable Products, Ronan McDermott has spent the last decade working with innovation on specialist heritage renovations across Ireland and the UK. He talks to AIDAN PRIESTLEY about disrupting the status quo when it comes to building materials
In the ever-evolving landscape of sustainable living, one revolutionary material is emerging as a game-changer in the realm of home insulation – hemp.
What sets hemp insulation apart according to Ronan McDermott, Director of Hempbuild Sustainable Products Ltd, is its remarkable adaptability, seamlessly integrating into various architectural styles.
Its versatility extends to retrofitting existing structures, presenting a viable solution for upgrading the housing stock sustainably.
As a crop, hemp boasts a rapid growth cycle, maturing in just a hundred days, making it a highly renewable resource.
“What’s more, it’s actually carbon negative when you consider the carbon intake in growing and energy requirements for processing it,” he says.
Hempcrete blocks help move towards more natural building methods
From seed to product, hemp embodies the ethos of sustainable living, offering homeowners a holistic solution for reducing energy consumption and minimising carbon emissions.
“Integrating hemp blocks directly onto concrete block houses brings a host of benefits,” he says. The benefit stems from the fact that unlike regular materials, hemp blocks have this ability to soak up and let out humidity, which keeps the indoor climate nice and stable.
“This ultimately reduces the need for mechanical intervention through the use of air conditioning, heating and so on, cutting down on energy use and making the space more sustainable,” Ronan adds.
In addition, using hempcrete is an opportunity to entirely replace traditional block built homes and plasterboard. Instead, you plaster right onto the hempcrete blocks, moving towards more natural building methods.
This switch also means using lime or clay-based plasters and breathable paints, making sure they play nice with hempcrete’s interaction with humidity.
“Going for hempcrete means changing the whole script, stepping away from the usual materials like cement and paint and choosing a greener path,” Ronan says.
But getting everyone on board with hempcrete might need some extra learning, especially when it comes to plastering with more natural ingredients.
A hempbuild project
Still, the basics of working with hempcrete are pretty simple, with skills in mixing more traditional cement into concrete being largely transferable to hempcrete with minimal training.
By using the natural abilities of hemp blocks to control temperature and humidity, buildings can become more energyefficient. Plus, shifting to hempcrete means embracing a different way of building, one that puts the environment first.
Ronan says he wants to ask the industry whether it “can build new homes free from chemical residues?” He believes hempcrete is the solution. “With its natural composition, hempcrete offers the prospect of a fresh living environment,” he adds.
He points to the potential health benefits. With Ireland experiencing annual humidity levels of 80 to 90 per cent he calls out mould as a serious concern.
“By maintaining interior humidity at optimal levels, stepping into a hempcrete house feels akin to entering a microclimate, devoid of harmful chemicals yet actively contributing to a healthier indoor environment,” he says.
“I think it’s important to include that hempcrete is a disruptor but it’s more so that it’s here to take part, not to take over.”
In his view, the product’s integration into various structural elements, alongside modern systems, offers a harmonious blend of tradition and innovation.
In this narrative, hempcrete signifies a paradigm shift – one where environmental consciousness takes precedence without compromising on modern comforts.
“The ability of hempcrete to retain heat far surpasses that of traditional concrete blocks,” he adds. “This means that once heat is introduced into a hemp block, it’s released slowly over an extended period, maintaining a comfortable indoor temperature.”
He paints an example as to how a traditional concrete home might be first heated, then a window opened for fresh air and in that process all heat is lost, whereas in a hempcrete home the heat continues to release from the walls while fresh air is circulating.
Ronan McDermott says hemp-based products can be a gamechanger due to their simplicity
Herein lies one challenge with wider adoption of hempcrete based homes. The current metrics for evaluating the energy efficiency for a home fail to account for the benefits of a material like hempcrete.
Ronan explains how the current U-value system, which measures how effective a material is an insulator for, informs the BER rating for a home.
In this regard concrete outperforms hempcrete, with the latter being a material that absorbs and releases heat, as opposed to insulates.
“It’s like having an iPhone in one hand and an old Nokia in the other, then asking you to choose on battery life alone, you’ll miss out on a whole world of features.”
Another challenge is that of mindset, with hempcrete involving a whole perspective shift.
“Stepping away from familiar practices and embracing something new can be daunting for many,” he says. “However, when we consider materials like hempcrete, which not only absorbs and retains heat but also releases it when needed, the traditional understanding of U-value becomes less straightforward,” he adds.
“There seems to be a tunnel vision approach, where the focus remains primarily on conventional metrics like U-value.”
Hemp based products can be a gamechanger due to their simplicity and transparency. However, its success relies on crucial factors: farmers cultivating it, Ireland fostering manufacturing facilities, and educating tradesmen on its usage.
“Hemp is a huge disruptor in this way, due to its simplicity if we can get the processes aligned behind it then we have a real recipe for success.”
Ronan McDermott was part of the Spotlight on sustainable building materials at the IHBA Housebuilding
Summit 2024 on April 16 in Croke Park
