Modern society needs buildings to function, but the building industry is one of the most environmentally devastating in the world. According to a 2018 report from the United Nations and the International Energy Agency, the building industry has the highest energy use and emissions of any industry.
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With increasing calls to minimize the building industry's environmental impact, building insulation material is one key area targeted for improvement. Currently, most building insulation materials have a significant negative impact on the environment.
Plastic-based insulation materials — such as expanded and extruded polystyrene — are the most common. While they offer several benefits in terms of thermal conductivity and water resistance, producing plastic insulation materials requires significant energy, approximately 39.75 MJ per kilogram. By comparison, 20 to 25 MJ is required to produce 1 kg of iron from iron ore, and 18 to 35 MJ is required to produce 1 kg of glass from sand. Polystyrene production also produces high carbon emissions, about 3.4 kg CO2 eq/kg. By comparison, producing glass bottles costs 1.1 kg CO2 eq/kg.
Although less prevalent than plastic insulation in commercial applications, inorganic insulations like fiberglass and stone wool generate fewer emissions than plastic insulation. However, they require heat-intensive production processes that require large amounts of energy. Furthermore, the production of inorganic insulation also generates significant emissions. For example, fiberglass production generates 1.7 to 2.2 CO2 eq/kg.
Perhaps more problematic is that the thermal conductivity of inorganic insulation materials tends to be higher than that of plastic materials. This means they are worse at insulating a building, potentially driving up heating and cooling costs. Inorganic insulation materials are also more expensive than plastic materials, making them a less popular choice.
The Life Cycle of Plastic Insulation Materials
Plastic insulation materials are the most popular because of their low cost, durability, lightweight, weather resistance, and design flexibility. Unfortunately, their entire lifecycle is plagued with environmental issues.
Several studies have shown that manufacturing processes for plastic building insulation materials generate much more toxic or greenhouse gases than production processes for other plastics. That being said, plastic insulation materials have a much longer lifespan, typically over three decades, compared to plastics used for packaging, textiles, and consumer products, according to a recent study in Sustainable Earth Reviews.
While plastic recycling efforts for consumer products are far from perfect, they can offset the environmental impact of these products. However, the nature of plastic insulation materials like expanded polystyrene makes them difficult to recycle. In Europe, the recycling of expanded polystyrene insulation materials is just 8%, compared to 34% for plastic packaging.
Natural Fiber Insulation as a More Sustainable Alternative
Building insulation materials made of coconut pith, hemp, and other natural fibers have emerged as a promising, more sustainable alternative to plastic materials. According to research, materials made of vegetal fibers have gained significant attention because they have a much lower economic impact than plastic and inorganic materials.
First and foremost, natural fibers are a renewable resource. Cultivating vegetation requires far less energy than the production of inorganic materials or plastics. As a bonus, plants sequester atmospheric carbon as part of their natural life cycle. When insulation made from natural fibers reaches the end of its life cycle, it can be biodegraded. These benefits directly address popular building insulation materials' many negative economic issues.
Cost is the most significant barrier to the widespread adoption of natural fiber insulation. Many of the plants used to make this type of insulation are not currently cultivated in temperate and Arctic zones, where installation is needed the most, adding supply chain costs. Furthermore, processing raw plant materials and using them to produce building insulation materials is also expensive. There are also concerns about natural fiber insulation materials with respect to water absorption, flammability, durability, and various mechanical properties. If these more technical barriers can be overcome, it may become more economically viable to scale up production and supply chain capabilities for natural fiber building insulation materials.
Conclusion
Even though it requires a high energy consumption and generates significant greenhouse gas emissions, plastic-based building insulation remains the most popular choice for the building industry.
Significant research and effort have focused on making natural fiber insulation more viable. However, it appears this more sustainable type of insulation can still not compete with plastic-based insulation in everything from cost to performance. It is possible that growing pressure to make the building industry more sustainable will focus more on developing natural fiber insulation materials. The need to make the industry more sustainable will only grow as demand for residential, commercial, and industrial buildings increases.
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References and Further Reading
Dovjak, M. et al. (2017) Environmental impact of thermal insulations: How do natural insulation products differ from synthetic ones? IOP Conference Series: Earth and Environmental Science. https://iopscience.iop.org/article/10.1088/1755-1315/92/1/012009/pdf
Zhoo, J. et al. (2022) A mini-review on building insulation materials from perspective of plastic pollution: Current issues and natural fibres as a possible solution. Journal of Hazardous Materials. https://www.sciencedirect.com/science/article/pii/S0304389422012420
Dickson, T. et al. (2021) Energy performance, environmental impact and cost of a range of insulation materials. Renewable and Sustainable Energy Reviews. https://www.sciencedirect.com/science/article/pii/S1364032121000472
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