Building Materials: From Production to Reuse

Reduce and Reuse: How to Cut Greenhouse Gas Emissions of Building Materials, Plastics, and Food

Find out more about the briefings in this series below:

Building Materials: From Production to Reuse

The Climate Consequences of Plastics

Reducing Emissions by Reducing Food Waste

The Environmental and Energy Study Institute (EESI) invites you to view a briefing series about the climate impacts of producing building materials, plastics, and food. Panelists explained the upstream greenhouse gas emissions generated from the production of these materials and discussed solutions designed to reduce those emissions at scale.

The built environment uses an immense amount of carbon-intensive materials such as concrete and steel. Switching building materials to lower-carbon alternatives can reduce the climate impacts of the built environment, but first, systems must be put in place to assess and reduce the carbon intensity of materials. When buildings reach the ends of their lives, there are also opportunities to reuse materials. Panelists discussed ways to reduce emissions and material waste in the built environment from construction and deconstruction.

Highlights

 

KEY TAKEAWAYS

Embodied carbon emissions are the emissions that come from building materials as they are extracted, processed, manufactured, transported, distributed, and disposed of. These are separate from emissions that come from operating a building. Embodied emissions can be reduced by using fewer building materials; reusing materials; optimizing the structure of the building for long-term durability; and minimizing waste during construction. Zoning laws, environmental product declarations (which report environmental impacts across entire life cycles), and building codes are three policy levers that can be used to incentivize the reduction of embodied carbon emissions in building materials. Federal funding for sustainable circular economy research and development initiatives could include creating innovative bio-based materials that are biodegradable; inventing technologies to disassemble existing buildings; developing materials passport technology (to track materials so they can be more easily recovered after demolition); testing pilot projects to see what works and what needs improvement; and mapping material flows and building component stocks to understand how materials are used in a city. At the national level, there is a need for a shared vision of a circular economy and for a circular economy action plan that will guide states and cities in developing their own local supply economies. There is also a need for clear targets, metrics, and indicators to monitor progress.

 

Jordan Palmeri, Environmental Scientist and Policy Analyst, Oregon Department of Environmental Quality

• Building materials have a life cycle and associated carbon emissions called embodied carbon. Embodied carbon emissions are the emissions that come from building materials as they are extracted, processed, manufactured, transported, distributed, and disposed of (end-of-life management).
• When comparing embodied emissions versus operational emissions (i.e., those released as the building is used), the proportion of emissions coming from embodied carbon is significant over the first 10 years of a building's life. In the first 10 years, the embodied carbon of the materials comprises anywhere between 38 to 67 percent of all the carbon emissions.
• Embodied emissions become even more important when building zero-energy buildings because they make up the building's only carbon emissions (such buildings have no operational emissions).
• There are multiple ways to reduce embodied carbon, including using fewer building materials; reusing materials; optimizing the structure of the building for long-term durability; requiring environmental product declarations (EPDs, which report environmental impacts across entire life cycles); and minimizing waste during construction.
• There are a number of policy options to reduce buildings’ embodied emissions, such as zoning, environmental product declarations, and building codes.
• Zoning controls where we build, how big we build, and more.
  • In Portland, Oregon, new zoning regulations limit the size of single-family homes unless they are built with multiple units or built to be adapted over time. Portland also passed a deconstruction requirement (which ensures that valuable materials are salvaged for reuse instead of crushed and landfilled) for residential homes built before 1940. This extends the life of materials and creates a material economy.
• Measurement and disclosure are the first policies we want to see implemented in terms of embodied carbon.
  • Vancouver, British Columbia, is the first place in North America to require that a portion of newly constructed buildings measure the impact of their building materials at the time of permit obtention.
• Environmental product declarations (EPDs) can help with measurement and disclosure. They are like nutrition fact labels, disclosing a building material's embodied carbon and other environmental impacts over its entire life cycle. They are third party certified.
  • EPDs help manufacturers identify where the hotspots are—where the impacts are and what should be targeted first to reduce emissions.
  • EPDs give the consumer an opportunity to choose lower impact materials. Similar to ENERGY STAR labels, which measure an appliance's efficiency, EPDs disclose how sustainably a product was made to begin with.
  • The Oregon Department of Environmental Quality has run a program for the last three years with concrete producers, in which it provides technical assistance and financial incentives to get EPDs on the market. The program is successful and has gotten over 1,500 EPDs published.
• Public purchasing policies can require EPDs for certain building materials; these are often called “buy clean'' policies.
  • In Portland, Oregon, they have a concrete procurement policy where they require EPDs on local city projects. They are also setting the maximum allowable global warming potential for concrete used in the city (the regulation should be published in a couple of months). Going forward, if you want to bid on a city project, you will not only need an EPD, but your concrete's global warming potential will also need to be below a certain threshold.
  • Portland has been running pilot projects to demonstrate that low-carbon materials can be used in the field by the traditional workforce doing this work. They are demonstrating how low-carbon concrete works in driveways and on ADA ramps. This is helping the city design its mandate, and also helping the whole workforce come up to speed on what it is like to use these newer materials.
• Another policy pathway for carbon reductions within building materials is through building codes. Marin County, California, was the first county in the United States to institute limits on concrete.

 

Dr. Fernanda Cruz Rios, Postdoctoral Researcher, Mascaro Center for Sustainable Innovation, University of Pittsburgh

• In a circular economy, buildings would be designed using modular and prefabricated components with demountable connections like bolts instead of welding or adhesives.
• Components could then be easily repaired or replaced separately (pieces have different lifetimes, and therefore need to be replaced at different times).
• Each building component would have a digital tag called a material passport that contains information like its location within the building, properties like strength and chemical composition, and environmental impact.
• When a building needs to be built or renovated, materials could come from products in the existing building stock. This is called urban mining and could replace much of the need for mining new materials. But we need financial business models that are compatible with this new way of doing things.
• At the national level, there is a need for a shared vision of a circular economy and for an action plan that will inform and guide states and cities in developing their own local supply economies. In addition to an overall plan, there is also a need for clear targets, metrics, and indicators to monitor progress.
• In the United States, there is a lack of awareness and information about the circular economy among both construction stakeholders and the general public. It will be critical to develop educational campaigns to raise awareness about the circular economy.
• Many stakeholders do not understand the difference between strategies like reuse and recycling. Not all strategies have the same environmental benefits.
  • For example, if a steel beam is reused in another building, it will have minimal additional environmental impacts. But when a beam is recycled, the recycling process will consume energy and create carbon emissions.
  • The efficiency of recycling varies according to each type of material. Less than 10 percent of plastics get recycled, but 98 percent of all structural steel is recycled back into new steel products without degrading its physical properties.
• Creating targets and policies that differentiate between reuse and recycle is key to harvesting the full potential of a product.
• Circular economy principles can be incorporated into public procurement. This can be addressed at the systems level, supplier level, or product level. For example, in Amsterdam, a recently constructed road will remain the property of the construction company. The construction company will maintain this road, and it is more likely that the materials will be upcycled at the end of its life cycle because the company will want to get the maximum value out of the materials it owns.
• Targets for salvaged components can be included in building codes.
  • Examples of common building materials that can be reused include brick, wood, glass, metals, and insulation.
  • Many existing building codes and regulations make strategies like adaptive reuse unfeasible.
• Federal funding for research and development initiatives that focus on the circular economy could include:
  • Creating innovative bio-based materials that are biodegradable.
  • Inventing technologies to disassemble existing buildings.
  • Develop materials passport technology.
  • Pilot projects to test what works and what needs improvement.
  • Mapping material flows and building component stocks to understand how materials are used in a city.
• It is critical to create fiscal incentives for the circular economy. The construction industry is risk averse and resistant to change.
• A Swedish author has just proposed a circular economy taxation framework that creates three different types of fiscal incentives over the product life cycle.
  • In the material production stage, there would be higher taxes for the extraction of new materials. These taxes can be applied to the manufacturers, but also to the retailers and to the final consumers when we are talking about consumer goods.
  • Reuse and repair tax relief that would make reuse practices more affordable and more available in the industry.
  • At the end of the product's life, there would be a waste hierarchy tax. There would be higher taxes for landfilling, lower taxes for recycling, and then no tax for any level above recycling—like reuse or remanufacturing.
• Circular economy policies must be designed with social justice at their core. This includes skills training for the current workforce so they can adapt to the circular economy model for different materials; ensuring that new circular economy models employ decent labor conditions; and enabling the active participation of communities in the way that we design our buildings and our cities. We need to be careful to avoid unintended consequences like environmental racism and gentrification when we make circular economy decisions.

 

Q&A

How is recycling different from reuse and why might it be suboptimal in some cases?

Cruz Rios: Here is an example to illustrate the difference between reuse and recycling. If you give your old laptop to your kid, you are changing the user but you are keeping the function. That is reuse. You have no additional environmental impact. When you send a laptop back to the store for a discount on a new one, the store is probably going to remanufacture your laptop, changing the parts and issuing a new warranty. That has increased impacts because of the new materials incorporated in the laptop. If you send the laptop to recycling, some materials are going to be separated to be recycled, but a lot of energy will be expended to extract and recycle that material.

Palmeri: One of my colleagues likes to sum it up by saying “recycling is necessary but insufficient.” When we look at the materials life cycle, most of the impacts are in producing that material. When we look at ways to reduce production-related impacts, getting more recycled content is one of those ways but it is not the only way to reduce the impact of materials today. We have done analyses that said, what if we recycled 100 percent of the things coming through the municipal solid waste stream? By how much more would we reduce carbon emissions? The answer was incrementally small.

It is important to remember that there are other things around the recovery economy that are beneficial. We have not talked about toxicity, jobs, or local economies, which are all important aspects of the recycling economy. Still, fundamentally, we are just consuming materials at a pace far faster than we could ever supply through recovered feedstock. So that is why we need different solutions.

 

How are the energy efficiency of a building and the building's embodied emissions related?

Palmeri: Building materials directly relate to the energy efficiency of a structure mainly through insulation materials and the mechanical systems that we use to heat and cool our buildings. The type of insulation really does matter. We used to use a lot of foam in buildings—this is extruded polystyrene foam that has great insulation value. But then we learned that the chemicals used to manufacture this foam have a super high global warming potential, and when these chemicals are released, they trap a lot of heat. You might have gone through a lot of effort to insulate your building, but what you did not realize was that it was going to take you 30 or 40 years just to make up for the impacts of those materials before you started seeing any of those energy efficiency gains. Thankfully, we have seen the global warming potential of the chemicals used in the insulation community coming down a lot in the last five to 10 years.

There is a lot of electrification going on in the building world right now. One of the issues we see happening with electrification is that we are using heat pumps. Heat pumps have refrigerants that have high global warming potential, and so we have seen federal legislation coming out on that over the last six months.

Cruz Rios: Circular business models can help us tie up loose ends around emissions. For example, imagine that a city needs a high-efficiency roof structure to improve the energy efficiency of a building. But the new technology can be extremely expensive. What circular business models can do is allow you to still harvest the environmental benefits over the life cycle of an energy efficient building. For example, by leasing the roof, you can have lower upfront costs of construction. This means you can invest more in energy efficiency and save funds to invest in other technology. At the end of the life cycle, the manufacturer will take materials back to use in other buildings. In this way, you have both an energy efficient building and there is a higher chance the materials will be reused at the end of the life cycle.

 

Looking ahead, what might be the next big policy or technology opportunities that would help us reduce the carbon footprint of the building materials we choose to use?

Palmeri: I have been thinking more about natural building materials and how we can match carbon cycles and buildings to what we see in the natural environment. We grow things like trees for 40 years, but a lot of the byproduct of lumber manufacturing is put to very short-term products, like pulp and paper. We lose that carbon in less than five years.

We are seeing a lot of interesting ways to just use less cement, and there are new cement chemistries. There is a lot happening with carbon sequestering aggregates and how to sequester carbon within the product itself. From a policy standpoint, one of the things I am really excited about is putting out demand for lower-carbon products at both federal and state levels. That is really helpful because if no one is there to buy it, then we are not getting the signal to the market.

Cruz Rios: There are huge problems and opportunities that we have to think about. What are we going to do with what we already have? What about all these buildings that we have that were not designed to be taken apart? How do we map, reuse, and disassemble these materials? For the material passports technology we talked about, how are we going to do that for existing buildings? There is some research going on about existing buildings to better understand what we already have.

It is critical to increase the durability of materials. One of the architects that I interviewed uses the term the “Walmart effect,” which means we are mass producing cheap building products and systems for developers to put into buildings, and they use these products because they do not have a long-term interest in the building. We have to keep ownership in mind because that affects the long-term durability and sustainability of a building.

Palmeri: One of the other policies that I am excited about is extending the responsibility of products to the manufacturers that are making them through product stewardship. We see a lot of product stewardship policies that are basically electronic recycling programs. But we are seeing more policies around the country that are starting to have manufacturers take responsibility over the entire life cycle of their product, and they are going to be way more incentivized to reduce the impacts of upstream production when they are responsible over the life cycle.

 

What are some things the federal government could do better to encourage innovation?

Palmeri: Supporting buy-clean legislation at the federal level that requires environmental product declarations (EPDs) for certain building materials puts the demand signal out there that we want low-carbon products. This can be compared to efficiency labels like ENERGY STAR. We need to see more programs and funding for agencies like the U.S. Environmental Protection Agency (EPA) to be able to collect publicly available life cycle information and start being a data repository so we can have more trust and confidence in the data when we start implementing EPDs far and wide. The federal government can play a larger role in not just providing the demand but in providing some of the actual funding for innovation within the industry and also taking more responsibility for product stewardship.

Cruz Rios: The federal government should create a clear circular economy plan that clearly communicates goals, targets, and strategies to disincentivize states and cities from all having different policies. Also, it is important to create platforms for discussion of the circular economy that allow different stakeholders to collaborate. The most successful circular economy strategies involve a multi-stakeholder network. These hubs and platforms can facilitate the exchange of ideas between researchers, non-governmental organizations, policymakers, designers, and communities.

 

Compiled by Emma Johnson and edited for clarity and length. This is not a transcript.