Sustainable construction has quickly become one of the industry’s top priorities, with innovative new methods and materials developing rapidly. One such example is lime-based inorganic paint enriched with graphene to tackle the downsides of traditional paints and act as an effective carbon dioxide (CO2) sink. This eco-conscious approach provides a potential option for construction projects of all kinds to further improve the sustainability of structures.

    How Does CO2 Absorbing Paint Work?

    One reason lime-based paint is used in sustainable construction projects is its ability to absorb and sequester CO2 from the air around it. The lime in lime-based paint refers to slaked lime, calcium hydroxide (Ca(OH)2). Once exposed to air, the calcium hydroxide reacts with CO2 to create calcium carbonate (CaCO3), the same compound found in natural limestone.

    Graphenstone is one manufacturer of lime-based paint, incorporating graphene into their formula to provide additional strength and crack-resistance. They state that three 15-liter containers of their paint can absorb upward of 10 kg of CO2. For perspective, a single mature tree can absorb over 20 kg of CO2 per year. However, most paints don’t absorb any CO2 at all, so lime-based paints are still a significant improvement.

    Manufacturing lime-based paints requires processing natural limestone to create calcium hydroxide. Limestone is primarily calcium carbonate. Once extracted, the limestone undergoes a process called calcination, where it is heated above 900°C and reacts with oxygen in the air to create quicklime, calcium oxide (CaO). Mixing this quicklime with water produces slaked lime, calcium hydroxide .

    Eco-friendly paint

    This is the ingredient included in lime-based paint that allows it to absorb CO2 from the atmosphere. When exposed to air, the calcium hydroxide reacts with CO2 to create calcium carbonate and water. The calcium carbonate stays in the paint, capturing the carbon from the CO2. The water simply evaporates. The end result is that the paint sequesters CO2 from the atmosphere.

    Awareness Campaigns for Eco-Friendly Paint

    Producers of CO2-absorbing paint have partnered with various organizations and artists to promote the ecological benefits of their projects. Some of the most stunning of these collaborations are murals on a massive scale that have been found throughout many different cities around the world. Large sections of building facades have been enveloped in artistic designs incorporating eco-friendly paint to make a powerful statement.

    Graphenstone paint, in particular, has been used in many such campaigns. At one time or another, you might have found buildings decorated with these murals in Toronto, Edmonton, London, Melbourne, Auckland, Bristol, Singapore, San Paolo, and more.

    While undoubtedly stunning, not everyone is on the same page about these campaigns. The organizations and artists surrounding these campaigns have made claims regarding their environmental impact that some experts disagree with.

    Criticisms focus largely on the fact that paint production still creates CO2 and makes the paint a net emitter when considering its entire lifecycle. They say that claims comparing the mural’s impact to that of planting some specific number of trees is misleading and disingenuous.

    Harmful Effects of Paint in General

    Traditional paints used throughout construction and home renovation projects can present a variety of environmental and health challenges. However, many of these issues are avoided entirely by using lime-based paint instead.

    Paints often contain volatile organic compounds (VOCs) that pose immediate and long-term health risks. These are organic chemicals that evaporate readily at room temperature. As they escape from the paint, they enter the air in the room. Depending on the chemical in question, they can persist there for some time, and paint can contain high enough levels of VOCs to present a long-term risk.

    Even when used outdoors, paint with high VOC content poses an environmental risk. They can contribute to ground-level ozone formation and smog. Both of these have adverse health effects, leading to reduced air quality and the risks that come with it.

    Paint also often contains petrochemical derivatives, which pose a variety of environmental concerns. They are sourced from fossil fuels, exacerbating the ongoing demand for increased production. Production of these derivatives produces significant CO2 emissions, increasing the lifetime impact of paint significantly.

    Lime-based paints avoid all of these issues. They don’t contain harmful VOCs, instead relying on lime to fulfill the core requirements of any effective paint. The limestone that the paint is made from is a naturally occurring mineral rather than a petrochemical substance. While mining and refining limestone still produces CO2 emissions, they are much less than in petrochemical processing.

    Benefits of Lime-Based Paint

    Investing in lime-based paint for your home or construction projects provides many long-term benefits. Of course, there is the previously mentioned environmental benefit. Instead of producing significant CO2 emissions like many types of paints, lime-based paint minimizes its lifetime impact by sequestering CO2 from the air when applied to surfaces.

    This reduced environmental impact means that many types of lime-based paint receive sustainability certifications and are eligible for a broader range of sustainability incentives and rebates. For example, Graphenstone lime-based paint is certified by the Cradle to Cradle Products Innovation Institute, among other organizations.

    You can also enjoy the long-term health benefits of reduced VOC emissions from paint, avoiding a variety of health risks. In addition to that benefit, lime-based paint also has natural antimicrobial properties that protect against mold, fungi, and bacteria. This type of growth is a common health concern in indoor areas, and lime-based paint helps mitigate that risk.

    Lime-based paint also delivers in many other vital areas. It provides durability and longevity, especially when combined with graphene as in Graphenstone paint. The natural durability of lime-based paint is enhanced with further crack and flake resistance thanks to the structural integrity of graphene. Lime-based paints are breathable, allowing for moisture to escape from coated surfaces. This is vital when painting older structures that may suffer from moisture issues.

    Painting a More Sustainable Future

    Lime-based paint is one of many solutions being used today to tackle sustainable construction. It delivers both environmental and health benefits, along with excelling in the practical requirements of construction and renovation projects.

    If you’re renovating your home in the near future or are responsible for any type of construction project, consider lime-based paint a sustainable alternative – and let us know if you have any other exciting sustainable construction ideas!


    Contributing Scientists of This Article: 



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