CO2 removals from biogenic building projects. Created locally - with a global impact
"Reforest the planet and retimber the city"
Prof. Dr. Dr. Hans Joachim Schellnhuber, climate researcher & founder of the Potsdam Institute for Climate Impact Research
Buildings are responsible for around a third of global greenhouse gas emissions and at the same time represent one of the most effective and cost-efficient levers in the fight against climate change - according to leading experts. The targeted use of biogenic building materials not only makes a significant contribution to reducing emissions, but also stores carbon for decades. The potential amounts to 5 gigatons per year.
Our goal at milton.earth is to specifically promote the sustainable construction industry by providing transparent and high-quality CO2 certificates for biogenic building materials such as wood, hemp, straw and biochar. We rely on the "Global Construction C-Sink Standard" recommended by ICROA. This certificate, developed by the Ithaka Institute in accordance with the principles of the EU Carbon Removal Certification Framework (CRCF), accurately captures the net carbon sink performance of a building.
This means that the more CO2 a building binds through the use of biogenic building materials, the greater the amount of carbon that is removed from the atmosphere for decades. The transformation of the built environment - less steel and concrete and more biogenic building materials from sustainable management - creates two climate-relevant effects: the reduction of emissions through climate-friendly materials and the long-term storage of CO2 as a carbon sink.
Our calculations show that for every tonne of CO2 avoided, another tonne of CO2 is bound in the long term when sustainable building materials are used. This significant co-benefit makes every sustainable construction project a measurable contribution to climate protection.
Negative emission technologies (NET) are necessary
Many countries and companies are pursuing net-zero strategies to effectively combat the climate crisis. However, process and product optimization alone is not enough; CO2 removal from the atmosphere is essential to achieve the net zero target.
In the EU, natural methods of removing CO2 from the atmosphere are assigned to the so-called LULUCF sector(Land Use, Land Use Change and Forestry). Measures such as improved forest management, afforestation and peatland rewetting store carbon in the long term. The conversion of biomass into biochar increases the humus content of the soil and even binds CO2 permanently. Companies such as Microsoft prefer to invest in such sink certificates as they are comparatively inexpensive (less than CHF 50 per ton of CO2).
Technological processes such as bioenergy with carbon capture and storage (BECCS), for example CO2 capture at the Werdhölzli Zurich wastewater treatment plant, and direct capture and storage of CO2 from the atmosphere (DACCS), for example by companies such as Climeworks, are gaining in importance. However, these technologies are still at an early stage of development and are not expected to be available for industrial use until around 2040. The future technology mix is also still unclear, with different approaches being pursued depending on the initial situation.
In order to achieve the climate target of the Paris Agreement and the EU climate targets of 2040 and 2050, natural, temporary CO2 removals are therefore irreplaceable for the time being. This is also confirmed by the EU Climate Council and is reflected in the Carbon Removal Certification Framework (CRCF). These temporary sinks include, in particular, buildings made from biogenic materials. The advantage of these sinks lies in the aforementioned co-benefit (1 tonne CO2 reduction + 1 tonne C sink).
Buildings as C sinks have a global impact, but are created and certifiable locally (which makes them verifiable and "visitable").
CO2 withdrawals Satus Quo
Current total amount of CO2 extracted worldwide: 20-22 Gt CO2/year
Source figures: IPCC Report (Mitigation of ClimateChange), 2022, State of Carbon Dioxide Removal Report (2024), Current status (2022-2024): Natural methods ~99.9%, technology-based methods ~0.1%
Carbon removals (negative emissions) are a supplementary complementary measure. Avoiding emissions always comes first. According to the motto: Do your best, offset the rest. Natural (temporary) sinks are currently indispensable: the converted
~0.1% of this is currently accounted for by technology-based CDR methods, i.e. DACCS, BECCS etc.
~99.9% of this is currently accounted for by natural methods of extraction, i.e. LULUCF (land use, land use change and forestry) & oceans.
Buildings made of biogenic materials such as wood, straw or reeds are also natural CO2 reservoirs.
Graphic: Provided by Global CCS Institute
"By purchasing CO2 removal certificates, companies can make an important contribution to climate protection. They enable the development of innovative building materials and open up exciting business opportunities."
Briefly summarized:
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The European Union is pursuing the ambitious goal of reducing its greenhouse gas emissions by at least 55% by 2030 compared to 1990 levels and achieving climate neutrality by 2050. In 2024, the crucial role of CO2 removal in achieving these targets was officially recognized by the EU. It was the first major economic area to introduce a Carbon Removal Certification Framework (CRCF), which creates a legal framework for offsetting unavoidable emissions through carbon sequestration.
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CO2 can be sequestered in various ways, including storage in products, in agricultural sinks or in geological reservoirs. However, each of these methods poses specific challenges, particularly with regard to the long-term nature of CO2 sequestration. The CRCF places particular emphasis on the clear distinction between CO2 mitigation and CO2 removal. "Carbon removals" are strictly defined as the additional removal of CO2 from the atmosphere and not merely the omission of emissions. They are therefore also referred to as "negative emissions".
Through this clear framework, the EU is making a decisive contribution to achieving its climate targets and at the same time promoting greater awareness of sustainable carbon management practices.
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The quality criteria defined in the CRCF Regulation are intended to prevent greenwashing and make the measures to reduce greenhouse gases certifiable and tradable in the voluntary carbon market.
This market complements the mandatory EU Emissions Trading System ("EU ETS") and is becoming increasingly important for achieving global climate targets. Both companies and private individuals have the opportunity to contribute to climate protection by actively participating beyond legal requirements.
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The construction industry plays a crucial role in tackling climate change. As buildings are currently responsible for 39% of global carbon emissions, the decarbonization of this sector is of central importance and a major lever in tackling the climate crisis.
An increasingly sustainability-oriented construction industry must rethink "building" and increasingly rely on biogenic building materials, which have a far lower carbon footprint than traditional building materials such as concrete and steel. Wood, hemp, biochar concrete, straw, bamboo, grass or reeds used in buildings also bind CO2 and form a natural, temporary CO2 sink over the lifetime of the building. Buildings thus become part of the solution in the fight against climate change.
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The renowned Ithaka Institute has developed a new standard, the Global Construction C-Sink, to identify CO2 sinks. The building sink is calculated on a net basis: emissions from agriculture, processing, transportation and installation are deducted. The certification relates directly to the building itself (the building is the CO2 sink) and can be used for insetting (the building's own CO2 balance) or sold on to third parties. The new standard has been developed in accordance with the Carbon Removal Certification Framework Regulation ("CRCF Regulation").
emissions and CO2 removals
Temporary extraction using biogenic building materials is part of the solution and is already available today.
