Question 1

Why is it (sometimes) wise to fell trees?

Accepted Answer

Trees are champions at removing carbon dioxide in solid form, but forests are not. When all the sunny spots on a hectare of forest are taken, maximum vegetation is reached and the photosynthesis engine stops. All further growth of one tree comes at the expense of others that die in the shade. So a hectare of forest has a maximum amount of carbon it can hold in living trees. The dead wood is consumed by fungi, bacteria and insects and thereby becomes a cause of CO₂ emissions. The amount a hectare can absorb from the atmosphere amounts to about 400 tonnes of CO₂. We have found a way to double a mature forest's absorption to 800 tonnes in 50 years. With sustainable management (PEFC), you can harvest a small percentage each year to make room for new growth: 5 seedlings per harvested tree. If you store the harvested trunks underground permanently, after 50 years you have 400 tonnes above ground and 400 tonnes below ground.

Question 2

How much timber is available?

Accepted Answer

When timber prices rise, it is because demand rises and sawmills and foresters cannot scale up production fast enough. It is not because forest rangers have reached their limit of what they can sustainably harvest. When they fell a spruce, they plant five seedlings in its place and leave all the branches and leaves on the forest floor as nutrition for the new generation and to preserve biodiversity. There is a direct correlation between interest rates and the price of timber. When interest falls, everyone starts growing. When interest rates are high, sawmills close and the forest is neglected. A sustainably managed forest is much better for the climate than a neglected one. So when timber prices rise, it is because there is a shortage of capacity in the sawmill, but not in the forest.

Question 3

Is it better to use the timber for construction?

Accepted Answer

It is extremely important to use timber and other biobased products in housing and other constructions. It creates a friendlier environment for people and replaces concrete, whose production emits about 8% of all greenhouse gases worldwide. On top of that, it holds all captured CO₂ for 35 to 90 years. Some argue: the same cubic metre of timber underground holds it for thousands of years, but burying is a waste of a perfectly natural, renewable building material. What is better: bury or build? The good news is we don't have to make that choice. There is enough for both. So if we build a wooden house on wooden foundations, there is enough left over for everything else we want to use. Only 70% of the available annual regrowth is harvested in a sustainably managed forest. And only 30% of the harvested timber is used for construction. The rest goes up in flames and emits all the CO₂ the trees captured during their lifetime, either directly as fuel or indirectly as waste from paper or cellulose products.

Question 4

As humanity we want to plant more trees, so why would you fell them?

Accepted Answer

A healthy forest needs to breathe. A tree never stops sequestering CO₂, until it dies and rots (releasing the CO₂ again). We harvest very strategically: exclusively mature trunks, at most 2% of a PEFC-certified forest. This literally creates light and space in the canopy for new seedlings to grow and absorb CO₂. For every tree we harvest, about five new ones are planted. Normally, timber often ends up as paper or fuel (where the CO₂ quickly returns to the atmosphere); we store it safely as a foundation for thousands of years, turning the tree into a permanent carbon vault.

Question 5

How does Underground Forest guarantee the permanence of CO₂ removal?

Accepted Answer

We use the Biomass Carbon Removal and Storage (BiCRS) methodology. Sustainably harvested PEFC-certified spruce timber is driven vertically into deep, anoxic (oxygen-free) soil layers. Because the piles are far below the groundwater level, fungal growth and wood rot are impossible. This results in a durability classification of more than 100 years, supported by archaeological evidence from Venice, where wooden piles have remained intact in the ground for over 1,500 years.

Question 6

What happens if the groundwater level drops or in other extreme weather events?

Accepted Answer

The reversal risk is negligible. Extreme climate scenarios, such as rising sea levels or flooding, actually strengthen the anoxic zone because the area becomes wetter. Geological projections show that the groundwater level would have to drop by as much as 7 to 8 metres for oxygen to reach the timber. Against human intervention, such as unforeseen infrastructure excavations, we maintain a mandatory Buffer Pool of 2%. In the event of a calamity, credits from this buffer are cancelled, so the integrity of the sold credits is always guaranteed.

Question 7

Why are parts of the Netherlands (and the rest of the world) subsiding?

Accepted Answer

This problem occurs mainly in areas with boggy peat and clay soils, marshes and polders. To make these areas habitable or usable for agriculture, the groundwater level is often artificially lowered. This causes the peat to come into contact with oxygen, causing it to oxidise (burn). This process leads to ground subsidence and also causes enormous CO₂ emissions.

Question 8

What are the consequences of subsidence?

Accepted Answer

Without a deep, solid foundation, buildings and infrastructure would sink under their own weight into the soft mud or oxidising peat. That is why foundation piles are necessary. By using our wooden piles in these boggy areas and advocating for rewetting of the peat (peatland restoration), we safely support the buildings and also curb further subsidence and CO₂ emissions from the landscape.

Question 9

What are carbon credits?

Accepted Answer

A carbon credit is a tradeable proof representing one tonne of CO₂ that has actually and permanently been removed from the atmosphere. In our case, these fall under Carbon Dioxide Removal (CDR) via biomass storage. It is a tangible and measurable way to offset residual emissions and simultaneously invest in high-quality climate solutions.

Question 10

What are carbon credits used for?

Accepted Answer

In our model, they are the financial accelerator for the construction transition. Concrete piles are currently the industry standard because they are cheaper in total foundation costs than timber. The revenue from selling our carbon removal credits bridges this financial gap. These credits make it financially viable and attractive for builders, project developers and engineers to choose our carbon-negative wooden solution instead of polluting concrete. Without these certificates, the necessary transition to wooden foundations would not scale financially.

Question 11

Why should I buy a carbon credit from Underground Forest?

Accepted Answer

Because our solution offers a unique combination of scalability, certainty and local impact:

• 100+ year permanence: The timber is stored in oxygen-free (anoxic), wet soil layers so it does not oxidise.
• Double impact: It not only stores CO₂, but also directly avoids the heavy CO₂ emissions from concrete. We consider this avoided emission a co-benefit and deliberately do not convert it into carbon credits.
• Proven technique: We build on a technique already used by the Romans; cities like Venice and Amsterdam have relied on this principle for centuries.
• Local realisation: Projects are realised in the Netherlands, which is locally verifiable.
• Forest-strengthening: The project increases the absorption capacity of forests by creating space for new growth.

Question 12

Why do you need carbon credits? Isn't a wooden foundation cheaper anyway?

Accepted Answer

Although individual wooden piles may be cheaper in material, current construction standards require more piles for a foundation. As a result, a wooden foundation in practice often turns out to be more expensive than the market standard of concrete. The revenue from carbon credits bridges this financial gap. Without this revenue, the market would stick to polluting concrete.

Question 13

What is the difference between insetting and offsetting?

Accepted Answer

With offsetting, a company compensates its CO₂ emissions outside its own value chain (for example: a software company buys our credits to compensate their server emissions). With insetting, the emissions are reduced and compensated within the company's own sector or supply chain (for example: a construction company that uses our wooden foundations in their own projects to reduce their direct construction emissions and remove CO₂). Underground Forest serves both needs.

Question 14

Are the carbon credits certified and safe to include in our ESG reporting?

Accepted Answer

We issue exclusively ex-post credits, meaning the CO₂ has already actually been captured before the credit is issued. Our projects are certified by Rainbow and independently verified by Normec.

Question 15

Does this method have other positive effects (co-benefits)?

Accepted Answer

Absolutely. The project serves a dual purpose. On one hand, we make construction more sustainable by offering an alternative to concrete (we deliberately do not claim avoided emissions as a credit to guarantee absolute purity). On the other hand, we apply the method for active soil stabilisation in peat areas. By driving wooden piles into the peat, we physically raise the ground ("Volume Displacement"), allowing water authorities to raise the groundwater level without the surface flooding. This stops peat oxidation and the associated enormous emissions at the source.

Question 16

I'm a farmer or landowner, is this relevant for me?

Accepted Answer

Yes. Several of our certified projects are agricultural. In Berkenwoude a dairy farmer built a trench silo on a wooden foundation, in Reeuwijk a nature farm built a trench silo for dairy feed, in Kockengen Korrel a dairy farmer built a manure cellar and silage storage, and in Haastrecht-Benschop a farm had an agricultural road built on wooden piles — each time instead of concrete.

As a project developer, landowner or farmer you remove CO₂ with our wooden foundation piles. You receive direct carbon credits for your project, full Rainbow certification and transparency, guidance from A to Z and financial benefit through lower foundation costs.

Question 17

Can provinces or municipalities partner with Underground Forest?

Accepted Answer

Yes. Provincie Zuid-Holland is a government partner and co-organiser of our pilot in the Green Heart, and Provincie Utrecht is a government partner for climate and soil innovations in the province of Utrecht. Together we drive the transition to biobased construction — discover how we can accelerate the transition together.

Question 18

My company wants to make an impact and offset our emissions, is Underground Forest a good fit?

Accepted Answer

Yes, our credits are built for companies looking for real, measurable climate impact alongside compensation. Each credit represents 1 tonne of CO₂ permanently removed (100+ years) via wooden foundation piles driven deep into Dutch soil, replacing polluting concrete piles. Our impact is scientifically grounded in peer-reviewed methodologies, independently validated, and continuously monitored using satellite data and groundwater levels. Because we issue exclusively ex-post credits, you're only buying CO₂ that has already actually been removed, not a promise of future removal. All our projects take place in the Netherlands, giving you local transparency and a direct, tangible contribution to decarbonizing the Dutch construction sector.

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