Using sustainable — and creative — solutions in building materials can help create a more sustainable built environment
By MATTHEW MEAD
In the last 20 years the market for organic products has increased dramatically, with worldwide organic food sales reaching over $100 Billion in 2018, up 6 percent from 2017. Across the world, and in North America and Europe particularly, many signs are pointing towards consumers looking for cleaner, healthier, and more sustainable product alternatives, ranging from produce purchased off the shelf to detergents and cleaners used around the household. As a whole, the sustainability movement is driving increased awareness towards ideas like embodied carbon, toxicity, and product lifecycles – ideas that, for some, are compelling enough to drive consumer behavior.
The built environment is the last stop on the climate-fueled sustainability locomotive, but the question remains: Can we get there get there fast enough?
The EPA estimates that the average American spends approximately 90 percent of their lifetime indoors, so it seems only natural that we’d start applying the sustainability driven consumer mindset to where we spend most of our time. The built environment, however, is a big apple to bite given our ubiquitous acceptance towards the status-quo; it is hard to think about what is in our walls, and how the flesh and bones of our built world can impact our health. Regardless, there is cautious optimism that the authors of our built environment – that is the developers, architects, builders, and engineers – are slowly putting together the pieces of the sustainability puzzle.
Timing and speed towards figuring out how the built environment fits into the puzzle of sustainability is essential, because statistics point to the built environment itself being the largest piece. Architecture 2030, an organization empowering the building sector to adopt more sustainable alternatives, estimates that 40 percent of annual GHG Emissions come from buildings. What’s more is that global building stock will double by 2060. This spur of development will need to be designed to meet net-zero-carbon standards to mitigate environmental and climate impacts.
The scale of this transformation cannot and will not come from consumers alone; it requires top-down decision making and priority placement on designing and building to standards for a better world, happening in tandem with consumer demand. It is now more important than ever before that built environment industry professionals make sustainability standard operating procedures. We need to think more critically about what we’re building, how we’re building it, and what the environmental upfront cost is.
In our world of concrete, steel, glass, and timber, we have come to think of sustainability of the built environment in terms of a building’s performance, not its upfront environmental cost in terms of carbon. There’s a pathway towards using our built environment as a carbon sink, and it doesn’t involve elaborate technology that harvests CO2 from the atmosphere. There are building materials that can be used to permanently store carbon, while lending to longterm sustainable performance.
Understanding the need for high performing buildings that embody carbon, I have been studying the field of agricultural biocomposites for building materials since 2013. Our contribution to the sustainability solution in the US has involved using a surprising material combination: hemp and lime. This is where I am used to losing people; it’s easier to scoff at something that sounds fringe or niche than to think about how it can be implemented. However, what may seem fringe or niche here in the US and North America is becoming more standard practice in Europe, with thousands of buildings being constructed using a material called “hempcrete,” a specialized combination of industrial hemp stalks and limestone. There are numerous advantageous, both environmentally and in terms of performance, in incorporating hempcrete composites into a building assembly.
Hempcrete can provide a carbon-cured insulating thermal envelope material that is vapor-permeable. It solidifies through a carbonation process that takes CO2 out of the atmosphere, permanently storing it in the wall. Additionally, the cultivation of our agricultural aggregate takes CO2 out of the atmosphere at an impressive rate. An average figure of CO2 absorption estimates 1 acre of fiber variety industrial hemp can offset approximately 8,922 lbs of CO2.
Across Europe, the adoption of this material has driven market demand, resulting in more prefabricated materials using hemp and lime, such as building blocks. Building with hempbased bioaggregates in the US is becoming more feasible following the passing of the 2018 Farm Bill, which legalized industrial hemp cultivation nationwide on December 20th, 2018. Since the adoption of this legislation, the hemp industry has already grown rapidly, with states individually enacting Pilot Programs to study cultivation practices as early as 2014.
Achieving both long-term performance in the built environment with minimal, if not negative upfront carbon emissions is a difficult task without using materials that embody carbon themselves. Hemp-lime based biocomposites accomplish this, and while they may not be the only solution, alternative building materials should not be overlooked as they can be a valuable tool in striving for embodied sustainability.
Matthew Mead has years of general construction experience that served as the foundation for his interest in sustainable construction materials. He is the CEO & Founder of Hempitecture.