Issue 021 Cover

Two Carbon Targets

By Khaled Abou Alfa • 01 August 2019

On the 20th of April, 2010 the largest environmental disaster in history was about to begin. The epicentre of the disaster would be at the Macondo Prospect, in the Gulf of Mexico. The Deepwater Horizon oil rig would ignite and explode. It would go on to release 780,000m³ (210 million US gallons) of oil into the sea. The oil would flow for 87 days until it was finally declared effectively dead’. The company responsible for the disaster was BP.

BP Carbon Footprint Campaign Poster 

We cannot overstate the negative impact this incident had on the local environment. It is therefore with a great sense of irony that BP had spent the earlier part of that decade building its image as a company centred around environmental awareness. This was best encapsulated by the Beyond Petroleum campaign, which started in 2005. One of the lasting impacts of this campaign was the spread of a term. A term that would become part of our everyday vernacular and galvanise an idea for the very basis of our environmental future. BPs future as an advocate for environmental responsibility was all but finished after the 2010 Gulf of Mexico oil spill. While they continue to pay penance, at least they gave us a global idea to collectively rally behind.
The carbon footprint.

Defining Carbon

My first meaningful encounter with the term happened sitting at my desk. This was early into my working life as an engineer. A young lady, sheepish smile, approached my desk. Her face gave away the fact that she thought she was doing something a little odd. She tells me that she’s working on a project to determine the firm’s carbon footprint. Could I answer the questionnaire? Sure,” I say. Very topical.” She proceeds to ask me several questions from her list. Finally she arrives to her last question, How many business flights do you take a year?” At the time it was funny because as someone new to work, business flights would not be a consideration for many years. We both looked at each, knowingly, laughed and went about our days.

This interaction stuck with me because although I had my reservations, it seemed like a good idea. It felt like a good idea. Unlike many other sustainable drives I’d seen or been part of, this one seemed like it could have an actual impact. There was something sensible with an accounting method for energy usage. What I couldn’t predict at the time was how pervasive this metric was going to become in the years to come 1. We now live in a world where we use carbon as the metric for sustaining each of our lifestyle choices. Being aware enables us to make the decisions necessary to reduce our the amount of carbon dioxide we release.

When we refer to our carbon footprint, this is shorthand for the amount of carbon dioxide generated and released into the atmosphere. There are two main carbon components to consider, direct/indirect and embodied.

Direct and Indirect

In calculating the amount of carbon dioxide, we first consider the type of emissions made. These are either direct or indirect: 

  1. Direct emissions are those made from burning fuel in a car or airplane. Calculated based on emission factors, which are dependent on the type of fuel.
  2. Indirect emissions are those generated in a power plant and consumed at home or work. Calculated based on electricity emission factors. These are dependent on how the electricity was generated. Different regions may depend upon a combination of fuels, such as hydroelectric power, nuclear or fossil fuels.


An important part of carbon footprint accounting is embodied in all the products and services that we use. In the construction industry this embodied carbon describes the total impact of all the greenhouse gases emitted by the construction and materials of our built environment. Unlike direct or indirect emissions, the carbon associated withe embodied energy has not hit the mainstream. It does not have an established standardised definition. The current drive remains the need to decarbonise the grid. As buildings become increasingly more efficient, the importance of embodied carbon will grow.

C02 Equivalent

There are several quantities that measure carbon, the most common being the Carbon Dioxide Equivalent (CDE). This refers to global warming caused by all greenhouse gases released by activity over a period of time. This is measured in tonnes of CO2 equivalent (tCO2eq). The graph below shows the CO2 emissions by sector. By far the largest contributor being that used for Energy production2.


The United Nations Framework Convention on Climate Change, UNFCCC, is the body behind several global pacts on the issue of climate change. The Kyoto Protocol came first (signed in 1997) and was followed by the Doha Amendment (held in 2002). This was then ratcheted further with the Paris Agreement (signed in 2016). Which paved the way for the Marrakesh Partnership (signed in 2016). Ultimately collected together in the Katowice Climate Package (signed in 2018). The hope being that some meaningful change will occur before we run out of nouns to append at the end of cities around the world.

Over the last 25 years there has been an incredible drive to bring down our current carbon emissions. Published in 2018, the Intergovernmental Panel on Climate Change (IPCC) special report provides a sobering overview of our current trajectory. If we continue on our current path, the global average temperature is expected to increase by 3–5 °C by 2100. The focus of the report is to define the impacts if we are able to limit global warming to 1.5 °C. Things get much worse if we don’t achieve this target. The report warned that the window to keep global warming at 1.5 °C will close in 2030. To help steer us away from the abyss, the UN Climate Change Annual Report 2018 defines two distinct goals:

  1. Reduce our greenhouse gas emissions, to 45% below 2010 levels, by 2030
  2. Net zero emissions by 2050

The ambitiousness of the task ahead is best encapsulated in the following graph.

Global Trends


These global targets involve everyone in the world, across boundaries and industries. For those actively involved in shaping the built environment, the World Green Building Council has identified a clear and ambitious roadmap to help achieve these targets:

  1. Net Zero Carbon emissions from all new buildings by 2030
  2. Net Zero Carbon emissions for all buildings by 2050

We cannot underestimate the enormity of the task ahead of us. This is because we define net zero carbon as maintaining the amount of carbon dioxide emissions released on an annual basis to zero (or negative). There is a hierarchy to how this is achieved. In order of preference:

  1. On-site generation - energy generated on-site (wind, PV, geothermal).
  2. Off-site generation -  using energy made from a sustainable and carbon reducing project.
  3. Offsets - buying credits in sustainable and carbon reducing projects 

This hierarchy acknowledges that while offsets are necessary, they should not be the primary (or even secondary) means of achieving net zero carbon. They are an acknowledgement that not all buildings, and locations are created equal. It is important however to not loose sight of the fact that by moving the solution away, we become more complacent about the issue itself. Local legislation should be bold to encourage a more responsible energy profile.

The subject of carbon emissions is one of the most important challenges that we as a human race face in the coming decades. We’re at a critical junction in our role and life on the planet. We planted the seeds for this road decades ago. They continue to grow and the acceptance of having a levy or tax on our carbon spend will become a way of life in many countries. The world doesn’t not have infinite resources. Each of us has a role to play.

  1. Such as your electricity bill or as part of your annual car test (if you own one). I have yet to see it included as part of flight tickets.↩︎

  2. Energy in this context is defined as the emissions created for public heat and electricity production, manufacturing and construction industries and fugitive emissions.↩︎

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