Construction and demolition materials are recognized as one of the largest components of the solid waste stream in the US, according to a study at the University of Florida by The Department of Environmental Engineering Sciences, Engineering School of Sustainable Infrastructure and Environment.¹ The construction industry is responsible for over 30% of the extraction of natural resources, as well as 25% of all solid waste generated in the world.² This consumption of materials and production of waste from the building sector is due to a linear economic model that takes, makes, and then disposes of materials at the end of their life or service. The governing assumption under a traditional, linear view is that products and materials assembled for a one-time use don’t retain any potential for reuse.

Photo courtesy of CRL

In addition to being sustainable, products and materials that are recycled or reusable can also improve the health, welfare, and safety of families in residential settings.

However, a paradigm shift is occurring in the construction industry at large with the adoption of a Circular Economy (CE) model.³ Under a CE, materials are seen as existing within a closed loop and have a retained value. CE, as a model of economic development, promotes the maximum reuse or recycling of materials, goods, and components in order to decrease waste generation to the largest possible extent.⁴ Besides reducing waste and easing consumption, taking a circular view of construction materials and products ambitiously aims to innovate the entire chain of production, consumption, distribution, and recovery of materials and energy. The awareness of increasing constraints on the availability of resources, as well as the increasing demand for access to welfare and well-being, are the foundation of a circular view. These constraints make it evident that there is a need for new economic models capable of improving the efficiency and effectiveness of resource use.⁵

At home, applying the principles of a CE helps to close the loop on material waste, preserves natural resources, and works seamlessly to address a project’s sustainability goals. Often, using products and materials that are recycled or reusable also improves the health, welfare, and safety of families in residential settings. Products that embrace CE are available in multiple categories, including in exteriors, fenestration, and even in the energy that powers a home. They represent truly having it all.

Photo courtesy of PERC

The decarbonization of homes will require more energy options. Propane is an approved clean alternative fuel under the Clean Air Act of 1990.

Photo courtesy of PERC

Renewable propane is made by converting plant and vegetable oils, waste greases, and animal fat into fuel, creating a truly circular energy source.

Powering Homes In A More Adaptable, Efficient Way: Propane

The circular economy (CE) concepts of reduction, reuse, and recyclability of materials and components have successfully been implemented in diverse fields, from electrical equipment and furniture to textiles. However, CE application in the building sphere at large has a shorter history and is often limited to waste prevention and material management.⁶ The construction sector has a great potential to implement CE strategies, particularly through the adoption of eco-friendly products and technologies.⁷

A material that can achieve high performance targets and yet meet the most demanding environmental standards, including enabling a home to meet net-zero energy construction, is certainly a material worth considering in a sustainable home’s portfolio. Uniquely, this is also a material that can fuel and power a home – propane.

Propane is an ideal energy source for heating, tankless water heating, cooking, clothes drying, fireplaces, power generation, and more. Propane is a straight-chain alkane, with the carbon atoms structured C-C-C. In terms of individual carbon atoms, propane can be expressed as CH3CH2CH3 or C3H8. When combusted, C3H8 transforms into 3CO₂ and 4H₂O. Propane is not mined like battery materials or extracted like oil. It is primarily manufactured from natural gas as a by-product of methane purification. Propane’s low carbon intensity is why it is an approved clean alternative fuel under the Clean Air Act of 1990. Propane is methane-free, as opposed to natural gas. Over a 20-year period, one ton of methane has a global warming potential that is 84 to 87 times more than CO₂ alone.⁸ Because it vaporizes when exposed to air, propane does not harm soil and has negligible effects on the ozone. Similarly, propane poses no hazard to drinking water or marine ecosystems. Propane only ignites when in the presence of a specific air mixture and an ignition source above 920 degrees Fahrenheit, making it safer than other fuels. Using propane also prevents deforestation by replacing solid fuels such as wood and coal.

The U.S. Department of Energy’s (DOE) Office of Scientific and Technical Information says that large emissions reductions are achievable by embracing a broad range of opportunities, including the use of low- or zero-carbon alternatives. Decarbonization in homes will require more clean energy options. The DOE classifies propane as a clean alternative fuel. Propane makes ultra-efficient Combined Heat and Power (CHP) technology possible. CHP refers to on-site generation capable of providing reliable electricity. Unlike centralized electrical generation plants that operate at only 33% efficiency, CHP systems capture heat and achieve total system efficiencies of 60-80% for producing electricity and useful thermal energy. Some systems can achieve efficiencies approaching 90%.⁹ Almost no energy is lost as it travels from tank to application. The DOE Energy Star program gives propane a source site ratio of 1.01, compared to 3.03 for electricity from the grid. This means it takes 3.03 units of electricity to produce and deliver one unit of energy to a home, compared to only 1.01 for propane.

The flexible form factor of propane storage makes it easy to install in virtually any environment without disrupting sensitive habitat. A 500-gallon tank can hold enough propane to meet the annual energy needs of an average single-family home. A typical propane tank has a useful lifespan of between 30 and 40 years, is made from 85% recycled steel, and is 100% recyclable after service. The brass fittings used in the tank are made from a high percentage of recycled brass and are 100% recyclable.

Residential clients can also have the efficiency and comfort of gas appliances when natural gas is not available with a propane back-up. Propane is electric grid free, making it a valuable partner energy source at solar and wind generation facilities, or at off-grid homes. When solar and wind generation facilities are unable to produce, propane acts as a back-up, providing on-call power in emergencies.

The New Energy Frontier: Renewable Propane

Today’s propane can offer a truly renewable energy source because it is being made by converting plant and vegetable oils, waste greases, and animal fat into fuel. This not only circumvents disposal of waste grease and oil, but it also allows for a circular energy source.¹⁰ Renewable propane delivers a high-energy conversion so that BTU’s are not wasted, and it is price competitive. At the point of combustion, renewable propane is carbon neutral, meaning no new carbon is added to the atmosphere when renewable propane is burned. Renewable propane has an ultra-low carbon intensity—as low as ¹⁹. Because renewable propane’s chemical structure and physical properties are the same as propane produced from fossil fuels, renewable propane can be used for all of the same applications.

Photo courtesy of Bison Innovative Products

The ribbed ipê wood tiles are modular and allow for unique design layouts. The parquet pattern utilized in this home’s gorgeous rooftop deck give the wood tiles a varying, versus uniform, appearance. The ribbed surface not only adds an element of texture to the design, it also ensures the deck is slip resistant and remains scuff free.

Circular Materials In Innovative Exterior Products

A significant amount of all materials ever extracted in human history are locked within the built environment¹¹ suggesting that buildings will become a major material stock to supply future demand. Under the linear economic model, continued inefficient use of non-renewable materials will almost certainly cause significant natural-resource depletion. In contrast, the adoption of CE principle in the construction industry promotes the use of sustainable materials, maximizes material recovery, and avoids unnecessary waste generation and waste disposed to landfills.¹²

When thinking about decks and outdoor living and entertaining, sustainable products are not the first thing called to mind. However, leading manufacturers are making advances in waste capture to bring more closed loop products to market. FSC®-certified wood, used in outdoor decking, comes from forests certified by the Forest Stewardship Council® to meet high global standards for forest sustainability. FSC® certification assures wood products have positive environmental attributes and are backed by a global system of verification. Certain manufacturers are taking outdoor deck materials one step further, engineering planks and tiles from remnants or shorts from other milling operations.