Sustainability and Carbon Capture

Zero Carbon Buildings not so ‘Zero’

The AEC sectors inevitable path towards Carbon Offsets

Aditya Vinod Buchinger
Age of Awareness
Published in
10 min readJul 3, 2020


The Global Problem Defined: Fighting climate change is on the agenda of every entity’s ‘2020 action plan’. There is enormous pressure on various sectors alike to deliver on the Paris Agreements either through technological innovation or by structuring their business to combat climate change. Yet construction, one of the heavily polluting sectors, might not be adequately addressing the issue. Numerous design and engineering practices have made clear of their ambition towards Zero Net Emission (ZNE) in their project’s operations (called operational emissions) while neglecting the material, procurement, and construction emission (called embodied emissions). Nevertheless, in order to fulfil this ambition, the AEC sector may have to look towards carbon offsets as a way to achieve total ZNE. But a reliable and sizable carbon offset market does not exist as of 2020. In the absence of a regulatory organisation that can vet a project’s lifetime CO2e emissions, the emission figures presented by individual parties could be biased, non-comparable, and far from reality.

Building Emissions

Carbon emission (denoted as CO2e, carbon dioxide equivalent) is the release of carbon dioxide and equivalent greenhouse gases (methane, nitrous oxide and fluorinated gases) into the atmosphere by an individual, entity, system, etc, which has resulted in the increase in global temperatures altering the balance of our environmental systems at an alarming rate. In construction, you will find it measured in kgCO2e/m2.

Buildings emit CO2e in two ways:

  • Through its materials, procurement, construction, and end of life disposal referred to as Embodied emissions
  • In their lifetime of operations including heating, cooling, appliances, mechanical, cooking, and so on referred to as Operational emissions
Lifecycle diagram of the building materials. Image © Aditya Vinod-Buchinger. For Icon attribute list check reference

Studies on buildings using conventional construction methods indicate up to ~45% carbon emissions from operations and 55% embodied, upfront and end of life emissions (

As of now, the established frameworks target achieving Net Zero Emission only in building operations, focusing mainly on energy-efficiency.

Referring to the WorldGBC Framework. Image © Aditya Vinod-Buchinger, For Icon attribute list check reference

Emerging economies and developing regions like India & African nations have projected building floor area growth rate of nearly 400%; China, the Americas, the Middle East, Southeast Asia between 150 to 230%; the rest between 110 to 150% by 2050 (GABC).

Globally, the stats indicate a two-fold increase in building floor area by 2050 resulting in large demand for energy and materials and inrease in built-up land cover to correspond to this growing footprint.

Building Materials Emission

The construction industry accounts for approximately 55% of the total annual material use and buildings contribute 50% of the total emissions of CO₂e. The breakdown of global industrial carbon emissions shows that 55% comes from the manufacturing and processing of five stock materials: steel (25%), cement (19%), paper (4%), plastic and aluminium (3%) (BREEAM).

Source BREEAM, Image © Aditya Vinod-Buchinger, For Icon attribute list check reference

Cement manufacturers are now investing in carbon capture technology globally through scattered pilots projects at best successfully capturing 15% — 24% of their emissions. When 1 tonne of cement uses 0.58 tco2e carbon intensity.

IEA reckons ‘To be on track to achieve SDS (Sustainability Develeopment Scenarios) decarbonisation, capture technologies in cement production should be commercialised by 2030’

Yet, investment towards carbon capture technology is inadequate, disproportionate, and lacking in global reach. At present, we haven't progressed significantly in covering our existing emissions. Therefore, although design practices have made clear of their Zero Net Emission ambition, this might just not be possible unless they purchase additional carbon offsets.

Why the construction industry

‘Construction and built-environment are responsible for 39% of energy-related carbon dioxide (CO2) emissions’ (WorldGBC), and globally 55% of CO2e emissions from the manufacturing of building materials such as steel, cement, paper, plastic and aluminium (BREEAM). Since much of the focus has been entirely on energy efficiency, Zero Net Carbon until now refers to only building’s operational emissions. This is within its essence misleading.

For example, energy usage by a household around the world is disproportionate. Most countries source energy from coal-powered plants that have significantly higher CO2e emissions than others. Some countries have a higher need for thermal comfort increasing the heating/cooling frequency. Therefore, an energy-efficient structure is only at most an engineering challenge, and this has been established already for many years now. WorldGBC is only now focusing on adding a lifecycle assessment framework, assuming that should take care of energy, material and disposal.

Construction materials (such as cement, steel and plastics) and their sourcing can be more adversely polluting the environment depending on the location, type and scale of the project (for example; infrastructure vs residential). Therefore, in order to provide a fair comparison between the various typologies, an entire lifespan product assessment is critical to understand the real problem and can help target the solutions and effort to effectively reduce the CO2 emissions. This is referred to as value chain emissions.

Stages in a project for consideration in lifecycle assessment of carbon emissions. Image © Aditya Vinod-Buchinger. For Icon attribute list check reference section

What are the latest regulations/suggestions in place seeking climate action from design practises

WorldGBC, UKGBC, Environmental Protection Agency, all follow suit with the Sustainability Goals set out by the United Nations. I looked closely into the UKGBC framework.

UK Green Building Council (UKGBC) 2019 Framework where it identifies the following steps to achieving Net Zero Carbon buildings

  • Establish a net-zero carbon scope for embodied and operational emissions. There is also a plan to introduce, I assume, a Scope 3 level (whole-life assessment) emission framework
  • Reduce construction impact — assessment and disclose all impact from product and at various construction stages
  • Reduce operational energy usage — reduce energy demand & consumption, whilst also disclosing the figures on in-use energy consumption
  • Increased renewable energy supply through on-site and off-site sources
  • Offset any remaining carbon through recognised offsetting framework, and disclose the amount of offsets

Three important points that I disagree with this framework are

  • The lack of Net-zero carbon-whole life in the framework: This must be prioritised, assuming this is the project lifespan analysis framework.
  • Lack of clear definition of product emissions- At what stage can value chain emissions apply to a project. Because how a project sources it material can heavily impact the total emissions. It could amount to 20% or 90% of the total project's emissions.
  • Mention of disclosing the amount of offsets: The rate of offsets must be disclosed (and not necessarily the amount) so that it becomes clear whether the rate has been abated/subsidised or are in actual competitive. This must be included in the openly available CO2e emission report with a complete breakdown of all facts and figures, such as how many Metric Tonnes of CO2 were offset, at what rates, what projects were selected for offsets. I will explain this further in Offsets section below.

What does this mean for the construction industry?

This means that when the Whole-life assessment is introduced into the framework, the emissions of a project could double. As the industry is already struggling to keep up with low-emissions, the projects will definitely have to use Carbon Offsets in order to attain true ZNE. The problem with that though, is there are not sufficient projects in the world that can capture carbon that is already present in the atmosphere.

Is Carbon Offsetting the answer?

Carbon offsetting is the reduction in carbon dioxide and equivalent greenhouse gas (CO2e) emissions of an entity by compensating the emissions reductions made elsewhere. This is done usually through carbon credits, i.e, by purchasing the good green credits of one by another which is heavy on its CO2e emission. This encourages investing in zero-carbon projects, initiates funding for R&D, and also regulates the carbon emissions.

Diagram of the AEC sector offsetting against green projects such as solar and wind farms, and algae production. Image © Aditya Vinod-Buchinger. Icons attribute list provided below

The aviation sector, one deeply affected by COVID-19 pandemic, is avidly looking for carbon offsets as part of their negotiations with governments all across the world, in order to be receiving bailouts. Construction could/should be next.

The offset concept is not new to the AEC sector. For example; many countries have regulations that permit an increase in the building floor area (FAR-Floor Area Ration, or FSI-Floor Space Index) by purchasing additional land elsewhere, or allocating open spaces towards community engagement, reserving or maintaining part of the land as not-for-build, providing open spaces for nature reserves in large scale developments, and so on. Yet when it comes to climate action, there is no equivalent that is considered. Although one could argue that carbon offsetting is not in the scope of an architect, it definitely is as much in the scope as much as an architect optimising the building layout and efficiently utilising the built-up area.

Where can one purchase Carbon Credits

Carbon credits are traded in the open market. The United Nations Framework Convention on Climate Change (UNFCCC) have vetted some climate-friendly projects and the Certified Emission Reductions (CERs) generate from that could be purchased to offset your carbon footprint. It is available for an individual, organisation, and businesses.

The issue with that is;

  • there is no transparency on how CO2e emissions are calculated
  • Value of credits very low indicating that companies can easily purchase these credits without facing consequences of their high-emission processes
  • CO2 sequestration from Oil and Gas also considered among carbon credits. This is bad. Extraction of natural gas releases CO2 and capturing it is not actively removing the CO2 from the atmosphere rather only limiting new release.
  • New technology on capturing carbon present in the atmosphere can be more expensive than burning methane coming out of a waste plant. One actively removes CO2 from the atmosphere, the other limits the release of GHGs. Yet they are both competing on this platform equally. New technology can therefore not attract any investments from such platforms due to poor comparison standards.

Criticism on carbon credits and carbon tax: Why I think Carbon Offsets and Emission Taxes are the lesser evil

It is the lesser evil because it instigates investments in technology towards carbon capture, which is lacking sufficiently at the moment.

The evil lies in business practice. As businesses seek the best value for their investment; in other words, the least rate for carbon credit, sectors that have large emissions to mitigate might drive up or down the price. This may also lead to non-availability of credits to purchase in the long run making them non-viable for smaller offsets who may also not receive abatements from the government.

What can AEC businesses actively do

  • Enforce the measures stated in WorldGBC, BREEAM, and others on projects worldwide
  • Encourage WorldGBC and others to evaluate their stand on the climate emergency to include a thorough framework
  • Keep up the utmost standard while measuring CO2e emission to ensure a like-to-like comparison
  • Disclose information on how projects have reduced CO2e emissions, how much credits were purchased, and where that money is ending up.

What will be the next issue

  • Lack of sufficient projects in the world to offset against
  • Snail pace technological advancement in carbon capture
  • Insufficient funds to support such innovation worldwide
  • The trajectory of growth of many developing/developed countries where climate action is not emphasised
  • Economic interests over climate action

What can you do

  • Bring these measures into your projects: Some 948 practices in UK have pledged through Architects Declare. This is a meagre number when the total number of registered architectural practices in the UK is about 7715. Additionally at the moment, regardless of their declaration, many practise favour clients by allowing them to make the ‘business as usual’ (meaning no interest in saving the planet) vs ‘green building’ design. Partly, this is because of the exorbitant costs associated with sourcing green materials. Takes us back to an earlier point -more funding in research and development of green materials/green construction/better framework/global cooperation.
  • Identify an advertisement from real commitment- Sustainability should not be used as an advertisement for practices. Request for detailed reports on how projects have achieved Net Zero Emission and evaluate if this has been vetted by a regulatory organisation (such as BREEAM).
  • Be aware of best practises when sourcing and procuring materials
  • Establish system thinking for design and evaluate Carbon impact at every stage
  • Enforce the same regulations outside the UK and Europe where country regulations might not be strictly supportive of climate action.
  • Evaluate design elements for its full lifecycle impacts
Source: Our World in Data

Next Article

In the next article, I will provide my take on emerging technologies and other methods (trees) that are positively removing carbon from the atmosphere. I am an enemy of methane combustions, and ONGC’s CO2 sequestration because I believe it is only poor practices best managed.

Thanks for reading.


Icons from attributed to Smalllikeart, Eucalyp, DinosoftLabs, Xnimrodx, Smashicons, Pixelmeetup, wanicon, Icongeek26, surang, Freepik, monkik, Icongeek26, pongsakornRed

Hello and thanks for checking out my post! Feel free to shoot any questions you may have as comments. Also, get in touch with me on LinkedIn if you would like to connect.

I am an architect (COA) and tech enthusiast from London. I am interested in the built environment and leveraging data sciences for architecture broadly around design, performance, and insights. I work on various topics from time to time such as generative design, spatial analytics, and energy and environmental studies. I am a Project Manager (AEC) at a biotech innovation company, developing a large-scale sustainable project in North Africa.



Aditya Vinod Buchinger
Age of Awareness

Architect | Climate actionist | Editor of Architectonics — a publication and knowledge sharing group opening up on sustainability in built environment