By taking these steps upfront, architects can make a big impact during the building stage of a project – The need for sustainability in the design, construction, and operation of buildings is a reality. According to the Energy Information Administration, about 40 percent of the energy consumed in the United States in 2015 went directly or indirectly to operating buildings.
- When you add embodied carbon—the energy and emissions from materials and construction—that number is almost 50 percent.
- As architects, we have the ability and responsibility to provide solutions that minimize the climate impact of the structures we design.
- And while practices to reduce operating impacts are widespread, less well understood are the carbon impacts during the building stage of a project.
My own “a-ha” moment on this front was when my firm calculated all the embodied carbon emitted from building the Portola Valley Town Center, It’s a very efficient project and has performed better than expected, but when we ran all the numbers we found that construction still emitted 1,000 tons of carbon—roughly the same as 10 years of operating emissions.
The good news is there are several steps architects can take to make significant upfront impacts in the design and construction process. Reuse buildings instead of constructing new ones. Renovation and reuse projects typically save between 50 and 75 percent of the embodied carbon emissions compared to constructing a new building.
This is especially true if the foundations and structure are preserved, since most embodied carbon resides there. With many projects, the first question should be, “Is there an existing building we can use instead?” This is an admittedly hard sell for architects—after all, many of us got into the business for the excitement and challenge of designing something new from the ground up.
- But channeling that energy and creativity toward making poor-performing buildings into something beautiful, sustainable and energy efficient has its own rewards, and yields substantial positive benefits.
- Specify low-carbon concrete mixes.
- Even though emissions per ton are not relatively high, its weight and prevalence usually make concrete the biggest source of embodied carbon in virtually any project.
The solution? Work with your structural engineers to design lower carbon concrete mixes by using fly ash, slag, calcined clays, or even lower-strength concrete where feasible. Though access to these materials varies across the country, with an increasing number of options there is almost always something that can reduce the carbon footprint of your concrete mix.
Limit carbon-intensive materials. For products with high carbon footprints like aluminum, plastics, and foam insulation, thoughtful use is essential. For instance, while aluminum may complement the aesthetics of your project, it is still important to use it judiciously because of its significant carbon footprint.
As architects, we have the ability and responsibility to provide solutions that minimize the climate impact of the structures we design. Choose lower carbon alternatives. Think about the possibilities. If you can utilize a wood structure instead of steel and concrete, or wood siding instead of vinyl, you can reduce the embodied carbon in a project.
In most cases, it’s probably not possible to avoid carbon intensive products altogether—metals, plastics, aluminum—but you can review Environmental Product Declarations and look for lower carbon alternatives. Choose carbon sequestering materials. Using agricultural products that sequester carbon can make a big impact on the embodied carbon in a project.
Wood may first come to mind, but you can also consider options like straw or hemp insulation, which—unlike wood—are annually renewable. Reuse materials. Whenever possible, look to salvage materials like brick, metals, broken concrete, or wood. Salvaged materials typically have a much lower embodied carbon footprint than newly manufactured materials, since the carbon to manufacture them has already been spent.
- With reclaimed wood in particular, you not only save the energy that would have been spent in cutting the tree down, transporting it to the mill, and processing it, but the tree you never cut down is still doing the work of sequestering carbon.
- Use high-recycled content materials.
- This is especially important with metals.
Virgin steel, for example, can have an embodied carbon footprint that is five times greater than high-recycled content steel. Maximize structural efficiency. Because most of the embodied carbon is in the structure, look for ways to achieve maximum structural efficiency.
Using optimum value engineering wood framing methods, efficient structural sections, and slabs are all effective methods to maximize efficiency and minimize material use. Use fewer finish materials. One way to do this is to use structural materials as finish. Using polished concrete slabs as finished flooring saves the embodied carbon from carpet or vinyl flooring.
Unfinished ceilings are another potential source of embodied carbon savings. Minimize waste. Particularly in wood-framed residential projects, designing in modules can minimize waste. Think in common sizes for common materials like 4×8 plywood, 12-foot gypsum boards, 2-foot increments for wood framing, and pre-cut structural members.
- 1 Which building material has the lowest embodied energy?
- 2 How can we reduce the embodied energy of concrete?
- 3 Which material has the highest embodied factor?
- 4 What is the difference between embodied carbon and embodied energy?
- 5 When can we reduce embodied carbon?
How do you tackle embodied carbon?
Why tackle embodied carbon – Developing net zero carbon assets requires driving down embodied carbon to an absolute minimum. As companies commit to net zero pathways for their own emissions, they are now focusing on reducing the carbon footprint of what they build. Regulating embodied carbon Embodied carbon has moved a lot higher up the agenda for industry and government. While it currently accounts for 11% of greenhouse gas emissions, with the projected increase of construction initiatives over the coming decades, it’s believed that,
Mandatory limits for upfront carbon emissions on al building projects over 1,000m 2 from 2027 Construction firms to assess and report on whole life carbon on all non-residential projects over 1,000m 2 from 2023 and residential projects from 2025
Building for resilience One of the main methods to reduce embodied carbon is by using more resilient materials that will last longer and are often produced via a more efficient construction process. Adopting these changes will reduce capital expenditure as well as maintenance, repair and replacement costs.
- Embodied carbon and planning consent Cost benefits aside, demonstrating your commitment to reducing embodied emissions is quickly becoming a key consideration in obtaining planning permission.
- Several local authorities – including Westminster City Council, Brighton, Oxford, Hammersmith and Fulham, Camden and City of London – have started to enquire about the embodied carbon footprints of developments.
Having an embodied carbon evaluation may soon make all the difference in the planning process. BREEAM, LEED and Green Star are all building rating systems that recognise embodied carbon measurement and mitigation as part of minimising the impact of a building’s life cycle.
Which building material has the lowest embodied energy?
Embodied energy of common materials – Generally, the more highly processed a material, the higher its embodied energy. Buildings typically use a large amount of materials with relatively low embodied energy (for example, bricks and timber) and smaller amounts of materials with high embodied energy (for example, steel).
Because most of the embodied energy of materials results from the manufacturing process, energy efficiency improvements within the manufacturing industries can make the most significant contribution to lowering the embodied energy of materials. Energy sources used to manufacture materials are also important to consider, given the large difference in environmental impact between renewable and fossil fuel-based energy sources.
Embodied energy values for some Australian materials are given in the following table, expressed as the amount of energy (in megajoules) per kilogram. However, these figures should be used with caution because:
the actual embodied energy of a material will vary depending on where and how it is produced materials manufactured with recycled content will have lower embodied energy, and savings will vary depending on the proportion of recycled content and manufacturing processes used materials of high monetary value, such as stainless steel, are almost certain to have been recycled many times, reducing their embodied energy compared with virgin materials.
Embodied energy of common building materials*
|Material||Embodied energy MJ/kg|
|Carpet – nylon||198|
|Carpet – wool||140|
|Concrete roof tile||4.3|
|Double glazing – flat (4:12:4)||66.8|
|Fibre cement sheet||18.3|
|Glass – flat||28.5|
|Hardwood – kiln dried||26.9|
|Laminated veneer lumber (LVL)||34.3|
|Medium density fibreboard (MDF)||22.0|
|Paint – solvent-based||124|
|Paint – water-based||111|
|Softwood – kiln dried||19.0|
|Steel – structural||38.8|
|Steel – corrugated sheet||79.6|
Note: These figures should be used with caution. See text above table. Source: Crawford, Stephan and Prideaux (2019). For most people, it is more useful to think in terms of building components and assemblies (for example, walls, floors, roofs) rather than individual materials.
|Assembly||Embodied energy MJ/ m 2|
|Elevated timber floor||2065|
|110mm concrete slab on ground, raft||1053|
|110mm concrete slab on ground, waffle pod||1838|
Source: Crawford (2019) Embodied energy for assembled walls
|Assembly||Embodied energy MJ/ m 2|
|Brick veneer wall, timber frame||1292|
|Brick veneer wall, steel frame||1387|
|Cavity clay brick wall||1973|
|Cavity concrete block wall||1276|
|Concrete block veneer wall, timber frame||965|
|Corrugated steel wall, timber frame||715|
|Hardwood weatherboard wall, steel frame||1421|
|Hardwood weatherboard wall, timber frame||1325|
|Polystyrene wall, timber frame||591|
|Reverse brick veneer wall, timber frame||1588|
|Single-skin autoclaved aerated concrete (AAC) block wall, plasterboard lining||2079|
Source: Crawford (2019) Embodied energy for assembled roofs
|Assembly||Embodied energy MJ/ m 2|
|Concrete tile pitched roof, timber frame, plasterboard ceiling||795|
|Terracotta tile pitched roof, timber frame, plasterboard ceiling||894|
|Corrugated steel sheet roof, timber frame, plasterboard ceiling||909|
|Corrugated steel sheet roof, steel frame, plasterboard ceiling||976|
Source: Crawford (2019)
What is a lower embodied energy?
Embodied Energy of Materials If we are careful in our choice of materials and processes we can minimise the ecological impact during a buildings construction and in its long term use. Energy is consumed to extract or harvest the raw materials that are used in construction products.
- More energy is used to transport these raw materials to the factories, where even more energy is used to transform the raw materials into finished construction products.
- All the energy consumed at each step along the way can be thought of as being ‘trapped’ or embodied in the final product.
- All the energy used up to the point where the construction material is ready to be shipped to the consumer is included.
The term used to describe this is ‘cradle to gate’ – meaning from the source of the raw material (e.g. forest) to the factory gate. Embodied energy is one of the key factors used to assess the sustainability of a construction material or product. Sustainable materials and products have low levels of embodied energy. A material that is locally sourced and is relatively un-processed will have a low level of embodied energy.
- While it is often true that the embodied energy of a material may be insignificant, compared to the energy-saving potential a material offers over the lifetime of a building, we should always aim to find and use materials which deliver on all aspects of environmental sustainability.
- Selecting materials for all the elements of a building is a complex and difficult task that requires careful consideration.
- Key Principles in assessing embodied energy of materials
- The energy consumed in producing, transporting, installing, maintaining and disposing of construction materials and products represents between 10% and 25% of the total lifetime energy consumption of a typical building. However, for low-energy buildings this figure can be as high as 50%. This is a really important point because it means that the impact of building materials is becoming much more important as more energy-efficient buildings are being designed and built.
- This idea is also very important for building design because it means that a balance has to be struck between the contribution a material makes to the energy efficiency of a building and the energy cost of producing that material. This is particularly relevant for insulation products. There comes a point at which it no longer makes sense to increase the thickness of insulation in a building because the energy saving achieved during the lifetime of the building or product is outweighed by the energy consumed to produce that insulation product.
Every company that sells construction materials and products is aware of the importance of making their products appear as ‘green’ as possible and most companies promote their system or product as being ‘greener’ or more sustainable than those of their competitors.
- Short term renewable origin (timber, wool, straw etc)
- Extracted or mined (earth, sand and gravel)
- Extracted and further processed (lime, cement, plaster, slate, stone, brick)
- Extracted and highly processed (steel, glass and plastics)
- Recycled or reclaimed (reused timber, brick, aggregate, steel, glass, insulation).
Key Principles for selecting sustainable construction materials Embodied Carbon
- They are designed for low energy use – they minimise the energy required to ‘run’ the building.
- They minimise the use of new resources – they are made using recovered, reused and recycled materials.
- They use whole un processed materials – materials like solid timber (in the round), natural stone, earth, clay and products that use natural fibres
- They have a low embodied energy – the energy used during the extraction/harvesting, manufacture and transport of a construction material
- They can be reused – for example, using lime-based mortar instead of cement-based mortar allows bricks to be reused because a lime mortar is softer than the brick and can be cleaned off without damaging the brick
- They contribute to a healthy indoor environment – for example, natural paints that do not emit volatile organic compounds (VOCs) and natural fibre (e.g. wool) carpets.
Key principles for selecting low embodied energy materials No product or material will be perfect in every respect. As an architect we have to consider an wide range of information and possibilities and then try to select the best solution.
- Source heavyweight materials locally: heavy materials like stone, aggregates and bricks should be purchased from local quarries and manufacturers because of the high amount of fuel required to transport heavy materials.
- Source lightweight materials globally: the proportion of embodied energy that is linked to transport is much smaller for lightweight materials (e.g. aluminium or PVC), especially when compared to the energy used in their manufacture. Many lightweight construction materials compensate for the embodied energy gained during manufacture by saving energy in the building once installed. For example, the aluminium foil used in insulation products saves lots of energy by reducing heat loss.
- Source materials with a high potential for reuse and recycling: the embodied energy that remains ‘trapped’ in materials at the end of a building’s life should not be wasted by sending the materials to landfill.
Life cycle assessment (LCA) is a tool used to calculate the environmental impact of a material or product. LCA takes into account all associated inputs and emissions, including:
- Energy consumption
- Greenhouse gas emissions
- Resource consumption (e.g. water)
- Pollution (air, water, land).
Both embodied energy and LCA need to be carefully considered when specifying materials and products for a project as they can have a major effect on the overall sustainability of a scheme. Hickey, T. (2014) ‘Designing sustainable homes’, Construction Technology, pp.102-106 Chapter 10 The Green Building Bible Vol.1, pp.195-198, Materials and Methods, Chapter 4 : Embodied Energy of Materials
What does embodied carbon mean and how does it relate to construction?
The 2020s are a make-it-or-break-it decade for addressing climate change: humanity must halve its carbon emissions by 2030 to meet the goals of the Paris Agreement. Given that buildings contribute around 40 percent of greenhouse gas (GHG) emissions worldwide, it is critical that architecture, engineering, and construction (AEC) professionals understand their role in reducing the sector’s carbon footprint—and how to use the tools available to assist them.
- For years now, the industry has focused its climate efforts on operational-energy consumption from lighting, heating, cooling, hot water, and other plug loads.
- And it has made great strides in increasing efficiencies and renewable-energy supplies.
- However, there is another, less obvious source of GHG emissions associated with buildings: embodied carbon.
It’s already in the atmosphere, quietly warming our planet, by the time materials reach the project site. And for new buildings, its climate impacts are nearly even with those of operational energy. Embodied carbon consists of all the GHG emissions associated with building construction, including those that arise from extracting, transporting, manufacturing, and installing building materials on site, as well as the operational and end-of-life emissions associated with those materials.
“Cradle to gate” embodied carbon refers to the emissions associated with only the production of building materials, from raw material extraction to the manufacturing of finished products; it can be thought of as supply-chain carbon, and it accounts for the vast majority of a building’s total embodied carbon.
Unfortunately, embodied carbon is more difficult to measure and track than operational carbon, which is relatively simple to extrapolate from occupants’ energy bills. Determining the embodied carbon of any building material is impossible to ascertain from the finished product alone and requires self-assessment and process transparency on the part of the manufacturer.
Two materials may look identical, cost the same amount, perform to the same standard—but have totally different embodied carbon characteristics. For example, a 100 percent recycled-steel beam produced using renewable energy may appear identical to a virgin-steel beam produced using a coal-fired furnace—but have significantly different levels of embodied carbon.
Where each steel beam came from and how far it was transported add further complexity. Accordingly, a nonprofit consortium of construction-industry players came together to develop what is now known as the Embodied Carbon in Construction Calculator (EC3): a free, cloud-based, open-source tool that utilizes data to power better materials choices and tackle cradle-to-gate embodied carbon.
How can we reduce the carbon footprint in construction?
The term carbon footprint refers to how much greenhouse gases (GHGs) are being released into the environment when using or manufacturing a product or performing an activity. Many gases can cause damage to the earth’s environment, such as carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulphur hexafluoride.
They affect the environment by keeping heat within the earth’s atmosphere. This can lead to warmer temperatures, changing climates, and destruction of wildlife habitat. Construction activities consume a lot of materials, create a lot of debris, and require a lot of energy. These types of activities can increase greenhouse gas emissions.
We’re going to look at how these activities create these gases, how to calculate your carbon footprint, and finally how to reduce or offset these emissions. What affects the carbon footprint of a project? There are three main construction activities that contribute to the carbon footprint of a project.
- They are the use of fossil fuels, using electricity, and sending refuse to the landfill.
- Use of fossil fuels – Equipment and vehicles that use traditional gasoline or diesel fuel are contributing to GHG emissions.
- According to the University of Michigan Center for Sustainable Systems burning coal creates 2.2 pounds of CO2, petroleum creates 2.0 pounds, and natural gas releases 0.86 pounds.
These fuels are often used by bulldozers, excavators, generators, dump trucks, pick-up trucks, and semi-trucks that transport materials to a project. The use of fossil fuels contributes about three-quarters of GHG emissions caused by humans. Electricity use – Electricity use goes hand in hand with burning fossil fuels.
Most of the electricity in the United States comes from coal-burning plants, which burn fossil fuels to make electricity. According to the Center for Sustainable Systems, each kilowatt-hour of electricity generated in the US creates 0.998 pounds of CO2 at the power plant. Almost all the tools and equipment that are used on a construction site are run by electricity.
Sending refuse to landfill – When construction debris is sent to a landfill, instead of being recycled, it wastes the energy that went into producing and transporting the material to the site in the first place. Construction projects create a lot of debris, whether from demolition activities, packaging material, or scrap material.
- Recycling allows the material to have a second life, and it usually doesn’t require as much energy to create a product from recycled material as it does from raw material.
- How to calculate carbon footprint Different gases create different levels of damage to the environment.
- The unit of measure for this damage is CO2e, or carbon dioxide equivalent.
Each type of gas is assigned a global warming potential (GWP), and this is multiplied by the amount of the gas that is released to come up with the CO2e. This calculation converts any quantity and type of greenhouse gas into the amount of CO2 that would have the same global warming impact.
- The Greenhouse Gas Protocol is the most widely used way to report carbon footprint.
- It was created in 2001 by the World Resources Institute and the World Business Council for Sustainable Development and has been used by businesses and organizations worldwide.
- Another popular method is ISO 14064, as it builds on many of the concepts in the GHG Protocol.
The first step in calculating carbon footprint is to define the boundary of the project that you are going to measure. Having a clear operational boundary will help you get consistent data over time. The GHG Protocol includes three groups of emissions that you may want to measure.
Scope 1 – Emissions that result from activities under your direct control. This could include on-site fuel combustion, process emissions, or company vehicles.Scope 2 – Emissions from electricity, heat, or steam you purchase and use. By using this energy, you are indirectly responsible for the emissions.Scope 3 – Emissions from sources outside your direct control, including purchased materials, employee commuting and travel, waste disposal, and water consumption.
Scopes 1 and 2 should be included in the project carbon footprint calculation. Scope 3 can be added if you want a complete look at the total impact of the project. Be sure to consider the difficulty in getting data when deciding which scopes to include.
Once you’ve decided on the activities you want to measure, gather data regarding fuel, electricity, and material use. You can use meter readings or utility bills to get electricity or natural gas usage. You may be able to look at fuel cards and bills to gain information on the amount of fuel being used in vehicles.
If that isn’t available, you can estimate based on the mileage on the vehicles and assumptions about fuel efficiency. Next, plug the usage information into a carbon footprint calculator, The calculator will use your data combined with standard emissions factors to come up with an overall score, expressed as tons of CO2e.
- Just as an example, the average US household creates 48 tons of CO2e each year.
- How to reduce the carbon footprint of your construction project The major contributors to a project’s carbon footprint are its fuel use, electricity use, and the amount of debris that goes into the landfill.
- Any steps you can take to reduce these factors is going to lower the carbon footprint of a project.
More specific measures would include: Reducing the amount of transportation that is needed to get materials to the site. This could include using green fuels, sizing trucks to handle loads more efficiently, and taking steps to improve the fuel efficiency of all vehicles and equipment on the site.
- Use construction materials made from recycled content.
- These materials usually require less energy during production, and you are saving them from going to the landfill.
- Supporting recycled material products also ensures that there will be a market for recycled materials.
- Recycle as much construction waste as possible.
The less material that goes to the landfill, the better it is for the environment. Sorting recyclable materials can cost extra time and money, so be sure to include this in your project budget. Add green building design features that improve energy efficiency, such as additional insulation, efficient HVAC equipment, LED lighting, and daylighting.
Also include the infrastructure to monitor energy use and report on where energy is being used the most. This is beneficial for spotting trends and changing user’s behavior to help save more energy. Modular construction is another construction method that allows for a lower carbon foot. See here, to learn more.
Ways to offset greenhouse gas release If you can’t control the emissions from the project to the degree that you would like, there are ways that you can offset them through investments. You can purchase carbon offsets, which provide investment funds for carbon-offsetting projects.
- There are many companies that offer these offsets.
- Be sure to research them thoroughly so you know where your money is going and that it is being used specifically to combat greenhouse gases.
- Many utilities allow their customers to select where their electricity comes from, including renewable power.
- You can make the choice with your utility or install a solar power panel or windmill on your property.
Installation of a power source will require more of an investment, but you also get to reap the benefits for years to come. If you don’t want to fund someone else’s offset project, you can always invest in your own. These projects include tree plantings, providing clean drinking water, wind farms, geothermal power plants, and solar projects.
- You can invest on your own property or use property in another location.
- Reduce, Reuse, Recycle The best ways to reduce the carbon footprint of a construction project is to reduce the amount of fuels that are being consumed, lower the rate of electricity use, and defer as much debris away from the landfill as possible.
If you want your project to not have a detrimental effect on the environment, then you can also invest in carbon offset projects, either your own or others’. These efforts will help ensure that your project enhances the earth’s environment as much as it does the built environment.
How can we reduce the embodied energy of concrete?
Abstract – Minimising carbon emissions from the building construction industry is of paramount importance in the present context due to the rising concerns of climate change. This paper explores the potential of minimising embodied carbon in reinforced concrete flat slabs by parametrically varying the slab thickness, grade of concrete, column spacing, column size, and reinforcement details.
A parametric design algorithm was developed to generate a range of one storey structural frames with flat slabs and to calculate their ‘cradle-to-gate’ embodied carbon per unit floor area while identifying the viable design space and relevant limiting criteria. Also, a parametric finite element model is parallelly developed to estimate non-linear long-term deflection and to investigate the possibility of further reducing embodied carbon by scrutinising the deflection related design limits.
The effect on the optimum designs by the adopted carbon coefficients is also quantified. The flat slab design with minimum embodied carbon for a given design load and column spacing corresponds to the minimum allowable thickness, largely insensitive to adopted carbon coefficients.
Relaxing the deflection limit can reduce embodied carbon but only by around 20% of the required percentage increase in the deflection. The possibility of reducing embodied carbon by providing more reinforcement to further reduce slab depths allowed by the deflection criteria is sensitive to the adopted carbon coefficients.
Minimising embodied carbon in flat slabs require optimising column spacing, using lower grades of concrete, and minimising slab depth based on deflection checks.
What is embodied energy in construction?
Definition – The dictionary of energy defines ‘embodied energy’ as “the sum of the energy requirements associated, directly or indirectly, with the delivery of a good or service” (Cleveland & Morris, 2009). In practice however there are different ways of defining embodied energy depending on the chosen boundaries of the study.
- The three most common options are: cradle-to-gate, cradle-to-site, and cradle-to-grave (Densley Tingley & Davinson, 2011).
- The following definitions illustrate this more clearly: 1) A cradle-to-site study favours defining the embodied energy of individual building components.
- This includes the energy required to extract the raw materials, process them, assemble them into usable products and transport them to site.
This definition is useful when looking at the comparative scale of building components and relates more to the ‘good’ in Cleveland & Morris’s definition as it neglects any maintenance or end of life costs. A cradle-to-gate model simply describes the energy required to produce the finished product without any further considerations.2) A cradle-to-grave approach defines embodied energy as that ‘consumed’ by a building throughout its life.
Initial embodied energy: the energy required to initially produce the building. It includes the energy used for the abstraction, the processing and the manufacture of the materials of the building as well as their transportation and assembly on site Recurring embodied energy: the energy needed to refurbish and maintain the building over its lifetime Demolition energy: the energy necessary to demolish and dispose of the building at the end of its life
Note that the cradle-to-grave embodied energy, i.e. its life-cycle embodied energy, does not include the operational energy required to utilise the final product. In other terms it does not account for the heating, cooling, lighting and power of any appliances that allow the building to serve its intended function.
Which material has the highest embodied factor?
Embodied Energy in Building Materials: What it is and How to Calculate It Usina de energia e centro de recreação urbana CopenHill / BIG. Image Cortesia de Laurian Ghinitoiu All human activities affect the environment. Some are less impactful, some much, much more. According to the United Nations Environment Program (UNEP), the construction sector is responsible for up to 30% of all greenhouse gas emissions.
Activities such as mining, processing, transportation, industrial operations, and the combination of chemical products result in the release of gases such as CO2, CH4, N2O, O3, halocarbons, and water vapor. When these gases are released into the atmosphere, they absorb a portion of the sun’s rays and redistribute them in the form of radiation in the atmosphere, warming our planet.
With a rampant amount of gas released daily, this layer thickens, which causes solar radiation to enter and and stay in the planet. Today, this ‘layer’ has become so thick that mankind is beginning to experience severe consequence, such as desertification, ice melting, water scarcity, and the intensification of storms, hurricanes, and floods, which has modified ecosystems and reduced biodiversity. CopenHill Energy Plant and Urban Recreation Center / BIG The term Embodied Energy or Embodied Carbon refers to the sum impact of all greenhouse gas emissions attributed to a material during its life cycle. This cycle encompasses extraction, manufacturing, construction, maintenance, and disposal.
- For example, reinforced concrete is a material with extremely high embodied energy.
- When manufacturing the cement, large amounts of CO2 are released in the calcination stage, where limestone is transformed into calcium oxide (quicklime), as well as in the burning of fossil fuels in furnaces.
- If we add these issues to the exploitation of sand and stone, to the use of iron for the rebar, to its transport to the construction site to be added to the mix, we can understand the impact of each decision of a project on the environment.
Other construction materials, such as ceramic, brick, and plastic, similarly require large amounts of energy to be manufactured since the minerals used in them must be extracted and treated in energy-intensive processes. Cortesia de ArchDaily It’s important to keep in mind that there are two types of carbon emissions in relation to buildings: Embodied Carbon and Operational Carbon, The latter refers to all the carbon dioxide emitted during the life of an entire building, rather than just its materials, encompassing electricity consumption, heating, cooling, and more. CopenHill Energy Plant and Urban Recreation Center / BIG. Image © Rasmus Hjortshoj Understanding the amount of energy or carbon incorporated in building’s materials is essential to creating more eco-conscious projects. A ‘sustainable material’ in one place may have a high energy load in another due to local availability and the type of transport involved.
A standardized method of quantifying the environmental impact of buildings, from the extraction of materials and the manufacture of products to the end of their useful life and disposal, is the Life Cycle Assessment (LCA), Using a quantitative methodology, numerical results are obtained that reflect the impact categories and provide comparisons between similar products.
To a similar end, the University of Bath (UK), has compiled a list comparing the energy content of the most commonly used materials around the world, Nest We Grow / UC Berkeley + Kengo Kuma & Associates. Image © Shinkenchiku-sha There are also other tools and technologies that promise to facilitate the process. Autodesk, together with the Carbon Leadership Forum and in collaboration with other construction and software companies, has developed the Embedded Carbon in Construction Calculator (EC3) tool, which is available to all beta users. Public Toilets in Zuzhai Village / cnS. Image © Siming Wu Editor’s Note: This article was originally published on 06/01/2020 and updated on 26/02/2021
Is low embodied energy good or bad?
Embodied Energy in Building Materials
- Chris Zecca – BCT
- Nealon Weir – BCT
- David Bailey – BCT
- Timothy Cowles- Environmental Science
- University of Massachusetts Amherst
In 2013, a mining company called Gogebic Taconite set its sights on the beautiful Penokee hills of northern Wisconsin. They proposed a four and a half mile long strip mine (which would eventually be expanded to twenty-two miles long) stretching across thirty-five acres of privately owned and managed forest land.
- The material mined from this project would be taconite, an ore that contains magnetite that is generally about 20-30% iron, typically of a low grade.
- To remove this iron from the ground, the mining company must remove forests, which are a natural carbon sink, and the top layer of earth, which, if aggregated, would be around 500 feet high and one and a half mile long (Iron Mining, 2015).
This doesn’t even begin to cover the tailings left behind by the mining process. Using a computer aided design program called Solidworks, an estimate was done stating that tailings created over thirty five years of operation would be enough to cover the entire country (over 3,750 acres of land) with forty seven feet of tailings.
For scale, an acre is just slightly smaller than a football field. The processes of land clearing, excavating, and mining are very fuel intensive, releasing tons of carbon dioxide into the atmosphere. In addition, a study by Bjornerud, Knudsen, and Trotter from Lawrence University shows that in the first thirty-five years of operation alone, two and a half billion pounds of sulfur would be released, which would combine with air and water to create acid rain.
Finally, the runoff from this mine would leach heavy metals including arsenic, copper, mercury and zinc, and would also release phosphorus (a major wetlands pollutant) into the watershed (2012). These pollutants are poised to affect the headwaters of both the Tyler Forks and Bad River (which both empty into Lake Superior), in addition to over fifty miles of streams and rivers.
The mine will also have a detrimental effect on the traditional wild rice fields of the Ojibwe and Chippewa Native American tribes, and the Penokee Aquifer, which provides clean drinking water to many residents (Iron Mining, 2015). The raw iron from this mine will eventually go on to be refined, and much of it will be combined with carbon to create steel which will be used for building materials around the world.
Steel is a strong alloy (mix of metals) that provides many structural benefits. However, the side effects of its production must be considered as well. Problem With outcomes as severe and widespread as these emanating from just a single iron mine, scientists have a difficult time accurately measuring the impact that removing resources has on our environment.
- This problem translates to the building materials that are created out of these resources, and the contractors, builders, and designers who work with them.
- While energy efficiency in buildings has been a focus in recent years, the creation of the construction materials themselves is often overlooked.
One attempt at quantifying what goes into building materials is the study of embodied energy, which measures the amount of energy that goes into creating building materials such as steel, concrete, and wood. In the construction industry, there is a gap in defining the term embodied energy when it comes to building materials.
- This is due to the fact that current interpretations of embodied energy are unclear, and varies greatly regarding what is included in the embodied energy calculations (Dixit, Fernandez-Solis, Lavy & Culp, 2010, p.1238).
- According to Dixit et al.
- 2010) embodied energy in the process of building material production includes: the energy used in harvesting the raw materials, such as mining and manufacturing, the transportation to on-site delivery, construction and assembly on-site, renovation, and final demolition (p.1238).
Embodied energy is also defined by Cabeza et al. (2013), who state that the embodied energies of the materials depend on the manufacturing process, availability of the raw materials close by, efficiency of production, and the amount used in the construction (p.538).
- From these two similar definitions, a parallel is drawn defining embodied energy as the amount of energy used from harvesting raw materials and the manufacturing process, while taking into account the energy used in the total transportation and installation of the building materials.
- Since there is not a clear consensus between many definitions to account for the demolition and disposal of a material, it is not included in our definition.
In today’s world, many believe the biggest global threat is climate change. In order to reduce climate change, society as a whole needs to start taking specific preventative measures. In the construction industry, a lot of energy is consumed. This causes environmental pollution and emissions of greenhouse gases that greatly contribute to climate change (Dixit et al., 2010).
One large contributor to this problem is the lack of consideration of embodied energy in the construction industry. Construction accounts for approximately 24% of the global raw material removed from Earth (Bribián, Capilla & Usón, 2011, para.1). As of now, Dixit et al. (2010) have calculated that “the building material (production) industry is responsible for 20 percent of the world’s fuel consumption” (p.1240).
With such an immense use of energy, the construction industry needs to address this embodied energy issue, which will lessen their energy usage and prevent the emission of large amounts of the greenhouse gases that directly contribute to climate change.
Often times, it is not up to the architect or contractor to decide which materials to use when designing and constructing a home. The owner, or largest shareholder in the construction of the building, has the final say in what materials will be used and where. There is little financial incentive for builders to use the most environmentally friendly materials, and owners often see little to no reason to choose the material with the smallest impact on our planet.
The smartest choice for most owners and builders is usually the cheapest option, and unfortunately, that is not always the best for the environment. Energy efficient materials, and those with lower embodied energy, may have a higher initial cost of installation (Balogh, 2015).
- By implementing incentives and stricter building codes, architects, contractors, and owners should use timber over steel and concrete in residential construction in order to slow climate change and lessen the environmental impact of building materials.
A material with a lower embodied energy uses less energy during its life cycle. This results in less resources consumed to extract raw material, produce specific parts, transport the product, etc directly leading to less environmental impact. Consuming energy results in the production of greenhouse gas emissions.
- Excess amounts of greenhouse gases lead to global warming and damage the environment, therefore embodied energy can be considered a measure of the overall environmental impact of building materials (Embodied Energy, 2014, para.1).
- Consequently, a material that possesses lower embodied energy will reduce carbon emissions produced and will limit the impact on the environment.
In residential housing, timber framed houses possess lower embodied energy than steel framed houses. The manufacturing of a building material is included in the embodied energy. Figure 1. shows that it takes 24 times less energy to produce one ton of wood than it does steel, making the manufacturing process for wood the most energy efficient compared to any other building material (Wood: Sustainable Building Solutions, 2012, p.5).
- The environmental benefits of using wood over steel in houses are displayed in a case study performed by CORRIM, which is the Consortium for Research on Renewable Industrial Materials.
- In the study they compare hypothetically built houses, one that is steel framed and one that is wood framed in the cold climate of Minneapolis.
They compare these houses by the life-cycle energy requirements and greenhouse gas emissions from the two homes, that have similar heating and cooling requirements, but are constructed from different materials (Upton, Miner, Spinney & Heath, 2008, p.8).
- Their conclusions found that timber built houses “required about 15-16% less total energy for non-heating/cooling purposes (compared to steel built houses)” (Upton et al.2008, p.8).
- If a wood base house is using less energy for heating and cooling purposes then it is reducing its environmental impact.
The results also found the greenhouse gas benefits of replacing non-wood materials with wood building materials are greater (Upton et al., 2008, p.8). This is because the “net GHG emissions associated with wood-based houses were 20-50% lower than (comparable steel based systems)” (Upton et al., 2008, p.8).
The wood based house emits less net greenhouse gases due to the low amount of GHG’s produced while manufacturing wood compared to the large amount produced when steel in made, this would help limit the environmental impacts by using wood over steel. Although less environmentally taxing than steel, concrete still possesses a higher embodied energy than timber (Upton et al., 2008, p.8).
Concrete uses limestone, the most abundant mineral on earth (Cabeza et al., 2013, p.538). This shorter transportation process helps reduce CO2 emissions of the material, lowering the embodied energy. Authors Upton, Miner, Spinney, and Heath. (2008) compared structures of a concrete and a timber wall home, and concluded concrete wall houses have roughly 15% greater energy demands than a wood framed house (p.8).
- Another reason that concrete has a higher embodied energy is the fact that it deteriorates over time, which results in more energy and resources used to restore the concrete structure.
- Wood buildings also require significantly less energy to process timber than concrete, which directly results in lower carbon emissions than concrete buildings (Cabeza et al., 2013, p.539).
Environmentally speaking, wood is clearly the best choice for the construction of residential buildings. The building material with the least impact on the environment is wood. One clear reason timber is better than steel and concrete is because wood is easier to extract and manufacture than the other two materials.
Wood is plentiful and all around us, and unlike steel, mining and extracting the materials from underground is not required. Timber is also relatively easy to process and form into sizes and shapes that are widely used across the construction industry. This results in less energy focused into making custom pieces of wood (Timber Frame Homes are Energy Efficient Homes, 2012, para 1).
Wood is also a reusable material, thus increasing the duration of the life of the material. Pieces can be reused on other project sites and excess framing can be utilized in other parts of the home. Timber frame construction also encourages the use of local resources, and the closer the extraction point to the project site, the less carbon emissions and embodied energy the material will possess (Timber Frame Homes are Energy Efficient Homes, 2012, para 2).
Wood frame homes also allow for more insulation to be placed between the vertical members, allowing for more retention of heat in the winter and helping to regulate cooling in the summer(Timber Frame Homes are Energy Efficient Homes, 2012, para 3). With better insulated homes, homeowners will see their energy bills and usage decrease, resulting in less energy being used during the occupancy phase of the home.
Lastly, wood acts as a carbon sink. A carbon sink is a reservoir that captures and stores a carbon compound for an indefinite period. Cabeza et al. (2013) states that timber products actually have a negative carbon coefficient. This means that timber products store more carbon over their lifetime than is released, which cannot be said for concrete or steel.
- Proposal One solution to decrease the amount of embodied energy in building materials would be to explore new ways to get contractors, owners, and architects to use timber over steel and concrete.
- By offering financial incentives such as tax breaks with the use of timber instead of steel and concrete there would be a greater chance of contractors and owners wanting to use timber in residential construction.
To understand how this would work, a parallel must be drawn between our proposal and a similar situation. Tax incentive (IRC section 45L) is a new energy efficient home tax credit that is a source of potential benefits for affordable housing developers, investors and owners (Boureois, Breaus, Chiasson & Mauldin, 2010).
- Energy efficiency improvements that encompass the building envelope of the property can qualify for certain tax credits on a case-by-case basis.
- Improvements such as upgrades to insulation or roofing materials qualify you for a credit that is worth up to 30% of the price of the materials that meet the qualification criteria during that current tax year (Boureois et al, 2010).
Similarly, if we apply this concept to favor the use of timber framing in the residential housing market it could be very efficient in reducing the overall embodied energy found in the building materials that are being used. To prove how this concept really works we can look at an experience in Oregon and the total financial benefits owners have received.
- Since 2001 Oregon developers of buildings certified LEED Silver or better have saved nearly $5 million and in 2006 the state received 29 applications totaling $13.7 million in eligible costs (Roberts.2007).
- By being able to point out how tax incentives will offset the cost of building at energy higher standards Oregon successfully increased the amount of energy efficient buildings and reduced the city’s impact on the environment.
Implementing stricter building codes may be more costly for the market, but would certainly play a role in reducing the impacts of embodied energy found in materials such as steel and concrete. For example, on January 1, 2011 the city of Los Angeles, California put into effect a set of mandatory Green Building code standards for new construction, alterations, and additions to residential and commercial structures (Kim, Green & Kim, 2014).This has resulted in increase of energy savings and has reduce the impact the city of Los Angeles has on the environment (Kim, Green & Kim, 2014).
By comparing two buildings, one that meets the green building code standard and one that did not meet the code, Jin-Lee Kim and Martin Greene concluded that the return on investment for more efficient systems could be very significant for owners(Kim et al., 2014). Implementing stricter building codes could help lower embodied energy in our building materials.
Resistant Audience One may pose that implementing stricter building codes and regulations into residential construction would raise the cost of the construction processes affecting the housing market. Although this may be true temporarily, the return on investment outweighs the initial costs of investing in building with timber framing systems.
Contractors need to educate and ensure owners that their investment will be worthwhile. The fact that these materials may be more expensive often drives away potential buyers. Under our plan, subsidies would offset costs and create incentives for those who choose to build with timber. Stricter building codes would also help to level the playing field by making sure that contractors are only able to choose between building materials with low embodied energy.
For example, Tax incentive section 1331, the Commercial Building Tax Deduction, claims that owners may claim a tax deduction related to the design and installation of energy efficient systems. “Building owners can claim a tax deduction of up to $1.80 per square foot of building area for the installation of systems that reduce the total energy and power costs by 50 percent or more when compared with a reference building” (State and local, 2008, p.7).
Drawing information from the previous example we see how the strategies used behind a similar tax incentive process benefits owners financially to a significant degree. Given this information and considering people’s general desire for money in the market, we can conclude that tax incentives would increase the use of wood in construction processes.
Conclusion The environmental impact of using energy intensive building materials is too large not to consider the embodied energy when constructing new buildings. Our proposal of increasing timber usage relative to concrete and steel using stricter building codes and financial incentives would help reduce embodied energy.
- This would in turn benefit the environment and the contractors and builders who use these materials.
- References Balogh, A. (2015).
- Do sustainable homes cost more? Retrieved from http://www.concretenetwork.com/concrete/greenbuildinginformation/do_sustainable.html Bjornerud, M, Knudsen, A, Trotter, J, (2012).
Geochemical, mineralogical and structural characterization of the Tyler Formation and Ironwood Iron Formation, Gogebic Range, Wisconsin. Retrieved from http://www.wnpj.org/pdf/Bjornerud_Geology_Report_Jan2013.pdf Boureois, M., Breaus, K., Chiasson, M., & Mauldin, S.
- 2010). Tax incentives of going green.
- The CPA journal, 80, (11), 19-26.
- Retrieved from http://web.a.ebscohost.com.silk.library.umass.edu/ehost/pdfviewer/pdfviewer?vid=14&sid=6a77f278-c7f7-468b-8d45-28e9e4010d6b%40sessionmgr4005&hid=4204 Bribián, I.
- Z, Capilla, A.V., Usón, A.A. (2011).
- Life cycle assessment of building materials: Comparative analysis of energy and environmental impacts and evaluation of the eco-efficiency improvement potential.
Building and Environment, 46, 1133-1140. doi:10.1016/j.buildenv.2010.12.002 Cabeza, L.F., Barreneche, C., Miró, L., Morera, J.M., Bartolí, E., & Inés Fernández, A. (2013). Low carbon and low embodied energy materials in buildings: A review. Renewable & Sustainable Energy Reviews, 23, 536-542.
- Doi:10.1016/j.rser.2013.03.017 Dixit, M., Fernandez-Solis, J., Lavy, S., Culp, C. (2010).
- Identification of parameters for embodied energy measurement: A literature review Elsevier, Energy and Buildings 2010, 42, 1238-1247.
- Doi: 10.1016/j.enbuild.2010.02.016 Embodied Energy. (2014).
- Retrieved from http://www.level.org.nz/material-use/embodied-energy/ Iron Mining: An Issue of Environmental Justice.
(2015). Retrieved from http://www.wnpj.org/penokeemine Kim, J., Greene, M., and Kim, S. (2014). “Cost Comparative Analysis of a New Green Building Code for Residential Project Development.” J. Constr. Eng. Manage., 140(5), 05014002. State and local green Building Incentives.
- 2008). Retrieved from http://www.aia.org/aiaucmp/groups/aia/documents/pdf/aias076936.pdf T, Roberts. (2007).
- Green buildings get tax relief.
- Green Source.
- Retrieved from http://greensource.construction.com/features/0704mag_policywatch.asp Timber Frame Homes are Energy Efficient Homes. (2012).
- Retrieved November 12, 2015, from http://planetsave.com/2012/01/06/timber-frame-homes-are-energy-efficient-homes/ Upton, B., Miner, R., Spinney, M., & Heath, L.S.
(2008). The greenhouse gas and energy impacts of using wood instead of alternatives in residential construction in the United States. Biomass & Bioenergy, 32 (1), 1-10. doi:10.1016/j.biombioe.2007.07.001 Wood: Sustainable Building Solutions. (2012). Retrieved from http://www.apawood.org/SearchResults.aspx?tid=1&q=f305 : Embodied Energy in Building Materials
What is the importance of embodied energy?
Embodied energy is the total non-renewable energy that goes into the manufacture of a material and plays a large role in the choice of building materials. It is an important factor to consider when assessing the life cycle of a building and it relates directly to the sustainability of the built environment.
What is the difference between embodied carbon and embodied energy?
Embodied carbon is the sum of greenhouse gas emissions released during the following life-cycle stages: raw material extraction, transportation, manufacturing, construction, maintenance, renovation, and end-of-life for a product or system. Embodied carbon is reported as global warming potential (GWP) and is measured relative to the impact of one molecule of carbon dioxide, usually over a 100-year time-frame.
- One kilogram of carbon dioxide has a GWP of 1 kgCO2e, whereas, for example, one kilogram of methane is approximately 28 kgCO2e.
- CO2e emissions released before the building or infrastructure use begins is sometimes referred to as upfront carbon.
- Upfront carbon is projected to account for half of the entire carbon footprint of new construction between now and 2050, threatening to consume a large part of our remaining carbon budget without even accounting for maintenance, renovation, and end-of-life embodied carbon emissions.
Embodied carbon is different from embodied energy, which only accounts for the energy use in all life-cycle phases of the built asset, regardless of energy source. Some amount of embodied energy may be from renewable sources and would not be considered a source of greenhouse gas.
Net embodied carbon calculations may include carbon sequestration and end-of-life considerations. Estimating end-of-life impacts is challenging due to their uncertainty at the time of design and construction. It goes without saying that material efficiency is a tenet of structural engineering best practices regardless of assessing environmental impacts or not.
One might think that more materials would equate to more cost, but oversizing often happens to simplify production and construction, which also reduces cost. Structural engineers also often unknowingly chose higher embodied carbon materials because they save time or cost for the project.
- These norms are starting to change however.
- Assessing environmental impacts of structural materials is becoming part of the decision matrix, and material quantities and the impacts of those materials are coming under closer scrutiny.
- Structural engineers today and of the future must understand how their designs not only impact architecture, MEP, cost, and constructibility, but also the environment.
All structural materials have different environmental impacts and design decisions made throughout a project, do in fact have an impact on a building or bridge’s overall environmental impact. Life cycle assessment (LCA) is how structural engineers can measure this impact.
A study published in the 2013 SEAOC Convention Proceeding illustrates just this. This study looked at 8 different structural/seismic systems (two concrete, two masonry, two steel, and two timber) for a prototype 5-story office building in Los Angeles, CA to assess the relative environmental impacts of these functionally equivalent alternative designs.
The study focused on the structural systems in isolation and did not address the non-structural impacts or operational impacts. For each structural/seismic system, the study used a building of the same size and dimension, with the same column layout, core area layout, perimeter curtain wall system, and equivalent floor quality in terms of sound-proofing and solidness.
While for some materials, this did not produce the most efficient structural designs, it was how the authors decided to create functionally equivalent buildings. This study found that the timber buildings generally had significantly less impact (on the order of 3 times less) than the steel buildings and the steel buildings generally had less impact than the concrete and masonry buildings.
While this was the case for this particular study, no general conclusions should be made about which material is the most environmentally efficient. Instead it points out that in fact structural systems do have different environmental impacts and that LCA should be used to account for these differences. Embodied carbon impacts of a building’s structural system are primarily associated with the different life cycle stages: material extraction, manufacturing and production, construction, damage and repair during service life, and end-of-life considerations. There are many opportunities for structural engineers to reduce the embodied carbon of buildings through:
reducing material quantities mitigating thermal bridging exposing the structure in lieu of providing finishes using protective systems with performance-based design using alternate structural systems than typically used for a particular building type utilizing lower carbon materials sourcing salvaged materials designing for deconstruction specifying materials with lower embodied carbon
These strategies, both at a material level and building level, must be taken with a holistic view to have the most beneficial impact. A designer needs to consider the environmental tradeoffs of design decisions, as well as the amount of potential saving a strategy offers and the timeframe for those savings.
Reducing embodied carbon in the structural system requires one to apply their skills as a structural engineer in the areas of system and material efficiency as well as in materials science. One needs to understand construction sequence and economics.To reduce embodied carbon one needs to understand embodied carbon, how it’s distributed throughout the building and find ways to reduce within the project program, cost and construction schedule limits.
See Resources for more information.
What building material has the highest embodied carbon?
Embodied Carbon in Building Materials: the Next Challenge for Vermont’s Net Zero Goals? by Matt Bushey, AIA and Members of the AIAVT COTE Committee Many of us have dealt with clean-energy skeptics over the years. Folks who dismiss solar panels because they claim more energy is used to produce the panels than they save.
Or that the manufacture of electric cars produces more emissions than a conventional vehicle. While these false claims have been thoroughly debunked, the argument is based on a kernel of truth: that products and materials do use energy to manufacture. The whole process of raw material extraction, manufacturing, and transportation can use a large amount of energy and produce significant greenhouse gas emissions before a product is even used for the first time.
This is what’s known as embodied carbon. If you have attended the AIA national convention or Efficiency Vermont’s Better Buildings by Design conference in recent years, you may have noticed that embodied carbon is getting more attention these days. We, as an industry, have gotten very good at producing buildings that use less energy to operate.
But the embodied energy of building materials has remained an elusive and persistent source of greenhouse gas emissions in a building. Embodied carbon of building materials constitutes 11% of global greenhouse gas emissions, a significant amount that can not be overlooked any longer. Nationally, the Biden administration has pledged to cut greenhouse gas emissions in half by 2030.
Here in Vermont, the Legislature has set a goal of net zero emissions across all sectors of the economy by the year 2050, with the recently passed Vermont Global Warming Solutions Act. To achieve these goals, it is going to be necessary to look at embodied carbon and transition to low-carbon materials.
- HIGH CARBON AND LOW CARBON MATERIALS Due to its abundant use and heavy weight, reinforced concrete is typically the biggest source of embodied carbon in a building.
- The manufacturing process for Portland Cement is energy-intensive, and when added to the embodied energy associated with processing sand, stone, and iron rebar, the end product is a major contributor to a building’s carbon footprint.
Adding fly ash to a concrete mix is one of the most popular ways to reduce its embodied carbon in our area. At Harrison Concrete, fly ash is available for up to 35% in a concrete mix, and is currently being used on all State of Vermont projects. Aluminum, plastics and foam have some of the highest levels of embodied carbon per pound.
Even if not used as prevalently as concrete, these materials can still add up to a big environmental impact. On the other end of the spectrum, wood and other bio-based materials have relatively low levels of embodied carbon. Here in Vermont, we are fortunate to have a strong wood products industry that follows sustainable forestry practices.
Mass-timber construction in particular offers great potential for carbon savings in low and mid-rise structures and is expected to break into the local market in the near future. Manufacturers are also coming out with low-carbon versions of products already on the market, such as bio-based MDF panels and reformulated gypsum wallboard that uses less water – and thus less energy – in its manufacture.
- Using salvaged materials, like brick and wood, and recycled materials is also a good strategy to decrease embodied carbon.
- For example, virgin aluminum has one of the highest levels of embodied carbon, with 11.5 kg CO2/kg of material, but if it’s recycled, that figure drops to 1.7 kg.
- IMPLEMENTING EMBODIED CARBON REDUCTIONS As established by the Vermont Global Warming Solutions Act, The Vermont Climate Council is currently working toward the development of a Climate Action Plan, which is expected to be delivered to the Vermont legislature by December 2021.
The Plan will include policy recommendations for reducing carbon emissions by 2050. AIAVT has been attending the meetings of the Vermont Climate Council over the past 6 months. At this time, it is unlikely that embodied carbon in building materials will be addressed in the first round of recommendations to the Legislature, but it may be included in later versions in the coming years.
- At that time, the approach for reducing embodied carbon may be similar to the approach taken toward the reduction of operational energy in buildings.
- Reducing operational energy use in a building has been achieved through a combination of “carrots” (such as incentives for energy efficiency measures by organizations like Efficiency Vermont), and “sticks” (such as building envelope standards established by the Vermont Energy code).
It is possible that a similar combination of carrots and sticks could be used to address embodied energy as well. Incentives could be offered for low-carbon materials, such as wood and concrete additives. On the legislative side, it is too early to say how embodied carbon limits would be implemented.
This could conceivably include the phase-out of products with high embodied carbon, or the establishment of maximum levels of embodied energy for a building. For this, measurement of embodied carbon would be a necessary first step. You can’t manage what you can’t measure. Fortunately, there is a tool that does just that.
EC3 – the Embodied Carbon in Construction Calculator tool – is a free online tool that architects can use to measure, compare and reduce embodied carbon in new buildings. EC3 was developed by a Washington state non-profit supported by a wide range of industry partners, manufacturers, and associations, including the AIA.
For many of us, the concept of embodied carbon in building materials may be a new one. As architects, we are well versed in the concepts of thermal performance and we can even calculate how much operational energy a new building will use. But embodied energy remains more of a mystery. With the right tools, incentives, and education, that can change.
And Vermont architects can be leaders in the adoption of low-carbon building materials and their role in meeting the state’s goals for net-zero greenhouse gas emissions. For more information on embodied carbon and material selection, visit the webpage, with links to relevant articles and downloads, including:
The Prescription for Healthier Building Materials: A Design and Implementation Protocol, a downloadable guide by AIA and ARUP, andThe AIA Blueprint for Better article Design Tools to Help Stop Climate ChangeThe AIAVT COTE Fact Sheet on Embodied Carbon in Building Materials:
: Embodied Carbon in Building Materials: the Next Challenge for Vermont’s Net Zero Goals?
Why is it important to reduce embodied carbon?
Why is Embodied Carbon Important? – Embodied carbon is relevant and important because we need to reduce greenhouse gas emissions for the future of the planet. But, remember that currently, embodied carbon isn’t necessarily measured for net-zero builds! This is because of the tendency to focus on operational carbon (only looking at the building once it is occupied), and that is a huge miss.
- Embodied carbon emissions will continue to increase with the increased global demand for construction materials.
- Giving our attention to the environmental impact of construction materials is absolutely warranted.
- When selecting materials, remember that plant-derived materials store the carbon dioxide the plants absorbed during their growth.
In other words, plants capture and store atmospheric carbon. Whether this stored carbon remains stored in those plant-derived materials depends on what happens to the materials at the end of the material’s life cycle.
How can we reduce construction waste?
Reduce, Divert and reuse and Recycle C&D Materials – You can help divert construction and demolition materials from disposal by practicing source reduction, salvaging, recycling, and reusing existing materials. You can also buy used and recycled products and materials.1.
- Reduce With source reduction, you can reduce the life-cycle of material use, energy use, and waste generation.
- The highest priority should be given to address solid waste issues.
- Source reduction prevents waste from being generated in the first place.
- Some examples of this include – preserving existing buildings rather than constructing new ones, optimizing the size of new buildings, designing new buildings for adaptability to prolong their life, use of construction methods that allow disassembly and facilitate reuse of materials, and employing alternative framing techniques.
Reducing construction and demolition debris also conserves landfill space, reduces the environmental impact of producing new materials, and can cut down the overall building project expenses through avoided purchase.2. Divert and Reuse Raw construction and demolition debris can be diverted and used as a resource.
- Landscape and land clearing debris
- Asphalt pavements
- Gravel and aggregate products
- Masonry scrap and rubble
- Clean wood
- Insulation materials
Recovering used but valuable construction and demolition materials for further use is an effective use to save money and conserve natural resources. Deconstruction can be used at a number of levels to salvage usable materials and significantly cut waste. It has the following benefits:
- Maximizes the recovery of materials
- Conserves finite forest resources
- Provides employment opportunities
- Allows communities to create local economic activities around manufacturing or reprocessing salvaged materials
- Diverts demolition debris bound for disposal
3. Recycle Many building components and construction debris can be recycled, Concrete and rubble are often recycled into aggregate and concrete products. Wood can be recycled into engineered wood products like furniture. Metals like steel, copper, and brass are also valuable resources to recycle. There are three methods for waste recycling:
- Site-separated : This uses multiple boxes for each type of waste. Separating construction waste on the job site gives immediate feedback to everyone on the job and can help to ensure that the project’s recycling goals are met. Site separation also promotes a responsible atmosphere on the job site and is the best method for diversion goals. It does, however, take up more space and requires a high level of supervision.
- Commingled recycling : This type of recycling uses one container. The hauler sorts everything off-site. This makes it easier for the field staff to manage waste on-site. Commingled recycling requires little storage space and is the best option for sites that are tight on space.
- Hybrid recycling : This type of recycling combines site-separation and commingled recycling. For instance, one box for wood, one box for concrete, and one box for non-recyclable waste. Hybrid recycling represents the best of both worlds. It optimizes the weight vs. sorting effort. The total number of boxes can be reduced by working in phases. It reduces work for sorting haulers, which reduces hauling fees.
For each project, the construction manager needs to assess the project requirements and site location to determine the best waste recycling method to use. Some questions to help with this are as follows:
- How many waste containers do you have room for?
- What will be their location on-site?
- Will you use a trash chute?
- Is it a high-rise site?
- Is it a high construction and demolition diversion project?
- Will there be enough staff onsite for required supervision
- Will there be changes in the waste generated during the project?
Engineers and construction companies should promote sustainable and eco friendly construction, They should carry out regular site inspections to verify that all construction waste management measures are in place and working properly. Haulers should create monthly construction reports on time.
What is embodied carbon in construction?
The embodied carbon of a building can include all the emissions from the construction materials, the building process, all the fixtures and fittings inside as well as from deconstructing and disposing of it at the end of it’s lifetime.
When can we reduce embodied carbon?
Strategies to Reduce Embodied Carbon in the Built Environment The Thermal Energy Center at Microsoft’s headquarters in Redmond, Washington, powers the campus almost entirely through electricity provided by geothermal energy exchanges. The project acts as a pilot program for the Embodied Carbon in Construction Calculator (EC3), a free database of construction EPDs and matching building impact calculator.
Image Courtesy of NBBJ The growing consumer demand for transparency —especially around sustainability and environmental practices—has implications for industries from apparel to healthcare products. Mars Inc. recently released a cocoa sourcing map to tackle deforestation and increase accountability, and the Fashion Transparency Index pushes apparel companies to be more forthcoming about their social and environmental efforts.
Now it’s time for the building industry, characterized by a lack of information around the materials and practices used in construction and throughout a building’s lifecycle, to catch up. The cost of inaction is too high to ignore. That’s because buildings account for 39 percent of total global carbon emissions. Embodied carbon consists of all the emissions associated with building construction, including extraction, transportation, manufacturing and installation of building materials on-site, as well as the operational and end-of-life emissions of those materials.
It is also largely “upfront” carbon —the greenhouse gas emissions that are released in the early phases of a life cycle—which means that its negative impact now cannot be reversed later. Most importantly, the magnitude of embodied carbon emissions between now and 2030 dwarfs the incremental impact of operational carbon, therefore, the immediate focus for embodied carbon reductions must be on the next decade.
In this post, we explore strategies to reduce it in the built environment.