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 stay on the planet. Today, this ‘layer’ has become so thick that mankind is beginning to experience severe consequences, such as desertification, ice melting, water scarcity, and the intensification of storms, hurricanes, and floods, which has modified ecosystems and reduced biodiversity.

As architects, one of our biggest concerns should be the reduction of carbon emissions from the buildings we construct. Being able to measure, quantify, and rate this quality is a good way to start.

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 the 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.

Credit: 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 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. The idea is to provide users with the information they need to make more informed decisions about the embodied carbon of each element of a building, promoting intelligent, conscious, and accessible solutions even for those who are not specialists. As always, awareness in making decisions and being conscious of the options available is always the best way to make processes more intelligent and sustainable.

Public Toilets in Zuzhai Village / cnS. Image © Siming Wu


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