Increased efficiency in construction through negative emission technologies
The final report on the accounting of negative emission technologies (NET) provides insights into the current challenges and solutions for integrating these technologies into the construction industry in order to achieve net zero emissions targets.
In order to ensure a clear distinction between the greenhouse gas emissions of the building and the negative emissions, these should be reported separately. Offsetting at the building material and component level is not recommended. Although buildings with net-zero greenhouse gas emissions are not yet achievable, they could be within reach in the future if greenhouse gas emissions from the production of building materials such as cement, steel, brick or glass are massively reduced.
In order to significantly reduce urban emissions by 2035/2040, the implementation and accounting of negative emissions technologies (NET) in the building sector is essential. A recently completed study has developed methods for integrating NETs into urban carbon reporting and formulated clear recommendations for the building sector in Switzerland.
A key finding of the study is that biogenic CO² and CO² extracted directly from the atmosphere must be stored for thousands of years in order to have a lasting impact on global temperatures. Temporary storage is not enough, as it cancels out the positive effects of subsequent re-emissions. A binding guarantee of permanence is therefore essential to ensure recognised NET accounting.
The study recommends accounting for NET in accordance with the SIA 2032 and 2040 standards. To ensure transparent accounting, it is essential to distinguish between negative emissions and greenhouse gas emissions from the building. Offsetting at material and component level should be avoided. The SN EN 15804 standard has shortcomings, as it shows an even balance of biogenic CO² even with permanent sequestration. It is important to use clear and precise language to emphasise the credibility of the statements.
Timber construction offers the greatest potential for negative emissions. Other renewable raw materials such as straw or hemp lime are promising but not yet widely used. Research should focus on ensuring durability and increasing the contribution of forced carbonation in mineral building materials. Although a net-zero greenhouse gas balance for buildings is not currently achievable, an important step in this direction can be made by drastically reducing emissions in the production of building materials.
The study emphasises the need for increased efforts to reduce greenhouse gas emissions, particularly in the production of building materials. It is recommended that local authorities provide financial support for the development of NET in order to achieve the desired climate targets.