Carbon is one of the most abundant elements in existence and forms the basis of all known life. But you can have too much of a good thing, and carbon is no different. Let’s look at what we mean by carbon and what impact the construction and demolition (C&D) industry has.
Earth has a very well-tuned system for moving carbon between the atmosphere, oceans, soil, and living organisms – called the carbon cycle.
Carbon becomes a problem when this natural cycle is thrown out of sync. When we use fossil fuels, carbon combines with oxygen (becoming carbon dioxide, CO₂) and gets released into the atmosphere.
Construction and demolition create significant environmental impacts globally, contributing to 38% of greenhouse gas emissions and 35% of global energy demand. Aotearoa New Zealand has committed to being zero carbon by 2050 – which means we all need to do our bit to reduce our emissions.
For around 100 years we’ve been creating more CO₂ than the earth can process. The CO₂ traps heat from the sun in the atmosphere, warming our climate on a global scale.
It may not seem like much, but a shift of only a couple degrees in the global average temperature has dramatic consequences like more frequent and more powerful extreme weather events.
Greenhouse gases, including carbon, are one of the biggest contributors to climate change and its ongoing effects on us and our environment. Cars, planes, power plants, and factories all emit greenhouse gases.
The Kyoto Protocol, an international agreement, defines six greenhouse gases:
• Carbon dioxide (CO₂) – From burning things like fossil fuels, waste, and plant matter.
• Methane (CH4) – From landfills, livestock, agricultural activities, and the production of coal, natural gas, and oil. It’s also far more warming than CO₂.
• Nitrous oxide (N2O) – From sewage treatment and burning fossil, but mainly from fertiliser and agricultural soil management.
• Sulphur hexafluoride (SF6) – The electric power industry uses this man-made compound for insulation and current interruption. Over 24,000 time more potent than CO₂ at trapping heat.
• Hydrofluorocarbons (HFCs) – From solvents, refrigerants, firefighting agents, and propellants for aerosols.
• Perfluorocarbons (PFCs): There are relatively low amounts of PFCs in the atmosphere, but they’re hard to get rid of. The estimated atmospheric life of this solvent and component of aluminium production ranges from 10,000 to 50,000 years.
A carbon footprint measures all the emissions (not just carbon) from an organisation, event, product, or person.
Not all gases are created equal – some have a more harmful effect than others – so a carbon footprint is calculated in equivalent tons of CO₂ (CO₂e). It adds together all the different greenhouse gases and consolidates it into one number, which is easier to understand and compare.
Once we have a measurement of the total carbon being produced, we can then work out ways to reduce our carbon footprint.
Carbon in C&D is typically split into two types – embodied and operational carbon.
This refers to the total greenhouse gas emissions from the production, transportation, and installation of materials, products, or infrastructure, right up until what is being built starts being used.
It also includes any emissions from demolition, and is measured in CO₂e. Understanding embodied carbon helps you choose materials and designs which minimise carbon emissions, improving your environmental sustainability.
• Raw material extraction: Emissions from the extraction of raw materials (e.g. mining of metals, logging for timber).
• Transportation: Emissions from transporting both raw materials to manufacturing sites and finished products to their final destinations.
• Manufacturing and processing: Emissions from the energy and processes used to convert raw materials into finished products (e.g. steel production, cement manufacturing).
• Construction and installation: Emissions from the construction process, including energy used by machinery and vehicles on construction sites.
Historically, measuring the environmental impact of buildings has focused on the construction phase, but that doesn’t capture the impact over its whole life cycle.
This content is brought to you by 3R Group, in partnership with Mitre 10 Sustainability on Site and BRANZ. For more information on how to be more sustainable on your building sites, head to www.mitre10.co.nz/trade/sustainability & https://www.branz.co.nz/reducing-building-material-waste
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