One way of attributing greenhouse gas emissions is to measure the embedded emissions of goods that are being consumed (also referred to as "embodied emissions", "embodied carbon emissions", or "embodied carbon"). This is different from the question of to what extent the policies of one country to reduce emissions affect emissions in other countries (the "spillover effect" and "carbon leakage" of an emissions reduction policy). The UNFCCC measures emissions according to production, rather than consumption. [1] Consequently, embedded emissions on imported goods are attributed to the exporting, rather than the importing, country. The question of whether to measure emissions on production instead of consumption is partly an issue of equity, i.e., who is responsible for emissions. [2]
The 37 Parties listed in Annex B to the Kyoto Protocol have agreed to legally binding emission reduction commitments. Under the UNFCCC accounting of emissions, their emission reduction commitments do not include emissions attributable to their imports. [3] In a briefing note, Wang and Watson (2007) asked the question, "who owns China's carbon emissions?". [4] In their study, they suggested that nearly a quarter of China's CO2 emissions might be a result of its production of goods for export, primarily to the US but also to Europe. Based on this, they suggested that international negotiations based on within country emissions (i.e., emissions measured by production) may be "[missing] the point".
Recent research confirms that, in 2004, 23% of global emissions were embedded in goods traded internationally, mostly flowing from China and other developing countries, such as Russia and South Africa, to the U.S., Europe and Japan. These states are included in a group of ten, as well as the Middle East, that make up 71% of the total difference in regional emissions. In Western Europe the difference in the import and export of emissions is particularly pronounced, with imported emissions making up 20-50% of consumed emissions. The majority of the emissions transferred between these states is contained in the trade of machinery, electronics, chemicals, rubber and plastics. [5]
Research by the Carbon Trust in 2011 revealed that approximately 25% of all CO2 emissions from human activities 'flow' (i.e. are imported or exported) from one country to another. The flow of carbon was found to be roughly 50% emissions associated with trade in commodities such as steel, cement, and chemicals, and 50% in semi-finished/finished products such as motor vehicles, clothing or industrial machinery and equipment. [6]
The embodied carbon of buildings is estimated to count for 11% of global carbon emissions and 75% of a building's emissions over its entire lifecycle. [7] The World Green Building Council has set a target for all new buildings to have at least 40% less embodied carbon. [8]
A life-cycle assessment for embodied carbon calculates the carbon used throughout each stage of a building's life: construction, use and maintenance, and demolition or disassembly. [9]
Re-use is a key consideration when addressing embodied carbon in construction. The architect Carl Elefante is known for coining the phrase, "The greenest building is the building that is already built." [10] The reason that existing buildings are usually more sustainable than new buildings is that the quantity of carbon emissions which occurs during construction of a new building is large in comparison to the annual operating emissions of the building, especially as operations become more energy efficient and energy supplies transition to renewable generation. [11] [8]
Beyond re-use, and excluding material extraction, which often accounts for high levels of embodied carbon, there are two principal areas of focus in the reduction of embodied carbon in construction. The first is to reduce the quantity of construction material ('construction mass') while the second is the substitution of lower carbon alternative materials. Typically—where reduction of embodied carbon is a goal—both of these are addressed.
Often, the most significant scope for reduction of construction mass is found in structural design, where measures such as reduced beam or slab span (and an associated increase in column density) can yield large carbon savings. [12]
To assist material substitution (with low carbon alternatives), manufacturers of materials such as steel, steel re-bar, glulam, and precast concrete typically provide Environmental Product Declarations (EPD) which certify the carbon impact as well as general environmental impacts of their products. [13] Databases that aggregate the embodied carbon values from EPD's and other sources such as academic studies, provide the embodied carbon values of many materials in one location, however the number of variables included in calculating the embodied carbon of building materials makes the values in the databases difficult to compare. [14]
Minimizing the use of carbon-intensive materials may mean selecting lower carbon versions of glass and steel products, and products manufactured using low-emissions energy sources. Embodied carbon may be reduced in concrete construction through the use of Portland cement alternatives such as Ground granulated blast-furnace slag, recycled aggregates and industry by-products. Carbon-neutral, carbon positive, and carbon-storing materials include bio-based materials such as timber, bamboo, hemp fibre and hempcrete, wool, dense-pack cellulose insulation, and cork. [15] [16] [17]
A 2021 study focused on "carbon-intensive hotspot materials (e.g., concrete foundations and slab floors, insulated roof and wall panels, and structural framing) in light industrial buildings" estimated that a "sizable reduction (~60%) in embodied carbon is possible in two to three years by bringing readily-available low-carbon materials into wider use". [18]
A variety of policies, regulations, and standards exist worldwide with respect to embodied carbon, according to the American Institute of Architects. [19]
Eight states introduced procurement policies related to embodied carbon in 2021: Washington, Oregon, California, Colorado, Minnesota, Connecticut, New York, and New Jersey. [20]
In Colorado, HB21-1303: Global Warming Potential for Public Project Materials (better known as "Buy Clean Colorado") was signed into law July 6, 2021. The law uses environmental product declarations (EPDs) to help drive the use of low-embodied-carbon materials. [21]
"In Europe, embodied carbon emissions have been limited in the Netherlands since 2018, and this is scheduled to happen in Denmark, Sweden, France and Finland between 2023 and 2027." [22]
"On May 10, 2023, Toronto became the first community in North America to require lower-carbon construction materials in new construction projects, limiting embodied carbon from new city-owned municipal building construction. New buildings must now limit upfront embodied emission intensity — emissions associated with manufacturing, transporting, and constructing major structural and envelope systems — to below 350 kg CO2e/m2." [23] The new requirements are currently voluntary for non-city-owned buildings.
Steelmaking is the process of producing steel from iron ore and/or scrap. In steelmaking, impurities such as nitrogen, silicon, phosphorus, sulfur, and excess carbon are removed from the sourced iron, and alloying elements such as manganese, nickel, chromium, carbon, and vanadium are added to produce different grades of steel.
Engineered wood, also called mass timber, composite wood, man-made wood, or manufactured board, includes a range of derivative wood products which are manufactured by binding or fixing the strands, particles, fibres, or veneers or boards of wood, together with adhesives, or other methods of fixation to form composite material. The panels vary in size but can range upwards of 64 by 8 feet and in the case of cross-laminated timber (CLT) can be of any thickness from a few inches to 16 inches (410 mm) or more. These products are engineered to precise design specifications, which are tested to meet national or international standards and provide uniformity and predictability in their structural performance. Engineered wood products are used in a variety of applications, from home construction to commercial buildings to industrial products. The products can be used for joists and beams that replace steel in many building projects. The term mass timber describes a group of building materials that can replace concrete assemblies.
Green building refers to both a structure and the application of processes that are environmentally responsible and resource-efficient throughout a building's life-cycle: from planning to design, construction, operation, maintenance, renovation, and demolition. This requires close cooperation of the contractor, the architects, the engineers, and the client at all project stages. The Green Building practice expands and complements the classical building design concerns of economy, utility, durability, and comfort. Green building also refers to saving resources to the maximum extent, including energy saving, land saving, water saving, material saving, etc., during the whole life cycle of the building, protecting the environment and reducing pollution, providing people with healthy, comfortable and efficient use of space, and being in harmony with nature. Buildings that live in harmony; green building technology focuses on low consumption, high efficiency, economy, environmental protection, integration and optimization.’
Embodied energy is the sum of all the energy required to produce any goods or services, considered as if that energy were incorporated or 'embodied' in the product itself. The concept can be useful in determining the effectiveness of energy-producing or energy saving devices, or the "real" replacement cost of a building, and, because energy-inputs usually entail greenhouse gas emissions, in deciding whether a product contributes to or mitigates global warming. One fundamental purpose for measuring this quantity is to compare the amount of energy produced or saved by the product in question to the amount of energy consumed in producing it.
Climate change mitigation (or decarbonisation) is action to limit the greenhouse gases in the atmosphere that cause climate change. Climate change mitigation actions include conserving energy and replacing fossil fuels with clean energy sources. Secondary mitigation strategies include changes to land use and removing carbon dioxide (CO2) from the atmosphere. Current climate change mitigation policies are insufficient as they would still result in global warming of about 2.7 °C by 2100, significantly above the 2015 Paris Agreement's goal of limiting global warming to below 2 °C.
A carbon footprint (or greenhouse gas footprint) is a calculated value or index that makes it possible to compare the total amount of greenhouse gases that an activity, product, company or country adds to the atmosphere. Carbon footprints are usually reported in tonnes of emissions (CO2-equivalent) per unit of comparison. Such units can be for example tonnes CO2-eq per year, per kilogram of protein for consumption, per kilometer travelled, per piece of clothing and so forth. A product's carbon footprint includes the emissions for the entire life cycle. These run from the production along the supply chain to its final consumption and disposal.
Coal pollution mitigation, sometimes labeled as clean coal, is a series of systems and technologies that seek to mitigate health and environmental impact of burning coal for energy. Burning coal releases harmful substances that contribute to air pollution, acid rain, and greenhouse gas emissions. Mitigation includes precombustion approaches, such as cleaning coal, and post combustion approaches, include flue-gas desulfurization, selective catalytic reduction, electrostatic precipitators, and fly ash reduction. These measures aim to reduce coal's impact on human health and the environment.
Sustainable architecture is architecture that seeks to minimize the negative environmental impact of buildings through improved efficiency and moderation in the use of materials, energy, development space and the ecosystem at large. Sustainable architecture uses a conscious approach to energy and ecological conservation in the design of the built environment.
Carbon capture and storage (CCS) is a process by which carbon dioxide (CO2) from industrial installations is separated before it is released into the atmosphere, then transported to a long-term storage location. The CO2 is captured from a large point source, such as a natural gas processing plant and is typically stored in a deep geological formation. Around 80% of the CO2 captured annually is used for enhanced oil recovery (EOR), a process by which CO2 is injected into partially-depleted oil reservoirs in order to extract more oil and then is largely left underground. Since EOR utilizes the CO2 in addition to storing it, CCS is also known as carbon capture, utilization, and storage (CCUS).
A Zero-Energy Building (ZEB), also known as a Net Zero-Energy (NZE) building, is a building with net zero energy consumption, meaning the total amount of energy used by the building on an annual basis is equal to the amount of renewable energy created on the site or in other definitions by renewable energy sources offsite, using technology such as heat pumps, high efficiency windows and insulation, and solar panels.
The Association for Environment Conscious Building (AECB) is the leading network for sustainable building professionals in the United Kingdom. Membership of the AECB includes local authorities, housing associations, builders, architects, designers, consultants and manufacturers. The association was founded in 1989 to increase awareness within the construction industry of the need to respect, protect, preserve and enhance the environment and to develop, share and promote best practice in environmentally sustainable building.
Greenhouse gas inventories are emission inventories of greenhouse gas emissions that are developed for a variety of reasons. Scientists use inventories of natural and anthropogenic (human-caused) emissions as tools when developing atmospheric models. Policy makers use inventories to develop strategies and policies for emissions reductions and to track the progress of those policies.
Greenhouse gas (GHG) emissions from human activities intensify the greenhouse effect. This contributes to climate change. Carbon dioxide, from burning fossil fuels such as coal, oil, and natural gas, is one of the most important factors in causing climate change. The largest emitters are China followed by the United States. The United States has higher emissions per capita. The main producers fueling the emissions globally are large oil and gas companies. Emissions from human activities have increased atmospheric carbon dioxide by about 50% over pre-industrial levels. The growing levels of emissions have varied, but have been consistent among all greenhouse gases. Emissions in the 2010s averaged 56 billion tons a year, higher than any decade before. Total cumulative emissions from 1870 to 2022 were 703 GtC, of which 484±20 GtC from fossil fuels and industry, and 219±60 GtC from land use change. Land-use change, such as deforestation, caused about 31% of cumulative emissions over 1870–2022, coal 32%, oil 24%, and gas 10%.
Energy in Switzerland is transitioning towards sustainability, targeting net zero emissions by 2050 and a 50% reduction in greenhouse gas emissions by 2030.
Carbon profiling is a mathematical process that calculates how much carbon dioxide is put into the atmosphere per m2 of space in a building over one year. The analysis has two parts that are added together to produce an overall figure that is termed the 'carbon profile':
Green building is a technique that aims to create structures that are environmentally responsible and resource-efficient throughout their lifecycle – including siting, design, construction, operation, maintenance, renovation, and demolition. A 2009 report by the U.S. General Services Administration evaluated 12 sustainably designed GSA buildings and found they cost less to operate.
Zero-carbon housing is housing that does not emit greenhouse gasses (GHGs) into the atmosphere, either directly, or indirectly due to consumption electricity produced using fossil fuels. Most commonly zero-carbon housing is taken to mean zero emissions of carbon dioxide, which is the main climate pollutant from homes, although fugitive methane may also be emitted from natural gas pipes and appliances.
The environmental impact of concrete, its manufacture, and its applications, are complex, driven in part by direct impacts of construction and infrastructure, as well as by CO2 emissions; between 4-8% of total global CO2 emissions come from concrete. Many depend on circumstances. A major component is cement, which has its own environmental and social impacts and contributes largely to those of concrete.
The wood industry or timber industry is the industry concerned with forestry, logging, timber trade, and the production of primary forest products and wood products and secondary products like wood pulp for the pulp and paper industry. Some of the largest producers are also among the biggest owners of forest. The wood industry has historically been and continues to be an important sector in many economies.
Carbon tech is a group of existing and emerging technologies that are rapidly transforming oil and gas to low emissions energy. Combined, these technologies take a circular carbon economy approach for managing and reducing carbon footprints, while optimizing biological and industry processes. It is built on the principles of the circular economy for managing carbon emissions: to reduce the amount of carbon emissions entering the atmosphere, to reuse carbon emissions as a feedstock in different industries, to recycle carbon through the natural carbon cycle with bio energy, and to remove carbon and store it. Carbon tech provides a third option for climate and environmental policy as an alternate to the binary business as usual and radical change.
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