Lots of resources are being invested into the development of various carbon capture and storage technologies, whereas photosynthesis does the same work without human effort. Unfortunately, landowners create more profit by taking the carbon out of their soils through clear-cutting forests and developing land for intensive farming or housing. This continuing trend is threatening Earth’s natural carbon sequestration capability, which is why we need to cut down on carbon emissions through a shift in consumer behaviour.

It has been estimated that the construction of a two-storeyed brick house weighing a hundred tonnes generates approximately 80 tonnes of CO2. That’s about as much as is emitted by a modern petrol-fuelled family car driving half a million kilometres. If bricks, cement or other mineral-based construction materials in the house were replaced by wood, the carbon emissions of the house would decrease due to it's significantly smaller carbon footprint and also due to the carbon contained in the wood fibre. To bring some perspective, a fullgrown spruce, weighing 14 tonnes, contains roughly 7 tonnes of pure carbon, the equivalent of 25 tonnes of CO2. This equates to the amount of carbon dioxide emissions sequestered from the atmosphere.

If the aforementioned brick house contained at least half wood by weight, it would equate to 90 tonnes of CO2, which is 10 tonnes larger than its carbon emissions, making the house effectively a carbon sink. Of course, it will function as a real sink only if the wood mass harvested for the house is replenished in equal or larger amounts. Luckily, Europe is one of the few areas in the world where forest areas have actually increased in the last 20 years, despite an increased demand for wood products. Thanks to the implementation of sustainable forestry practices, natural carbon sequestration in Europe is increasing. Now there is a way of communicating this message to the public - a carbon label for houses.

Greenline House is being developed as the world’s first carbon label for houses. The label aims to show both the carbon contained and emitted during its production, labelling houses on the basis of their climate impacts, e.g. A-class houses are carbon negative, B-class houses are carbon neutral and C-class houses have net positive carbon emissions. The calculation of carbon footprints will follow the ISO 14067 standard and include all cradle-to-gate carbon emissions from raw material acquisition, processing, transport and assembly. The Greenline House label is being developed in cooperation with AS Kroonpress, the Estonian Woodhouse Association and Tallinn Technical University.

Timber houses store carbon for a very long time, all the while providing shelter with a healthy microclimate. Seems like the case for brick houses is slowly crumbling.