New criteria for biogenic emissions?

The natureplus Criteria Commission has adopted a draft amendment to RL5010 that provides less stringent limit values for natural emissions from wood. This draft is to be discussed with experts in a hearing.

At its meeting in September, the natureplus Criteria Commission adopted a draft amendment to the Award Directive RL5010 "Low-Emission Construction Products". The basis for this was a specially prepared expert report which analysed numerous recent scientific publications on the subject and at the same time evaluated the testing experience of the natureplus-affiliated laboratories. The background to this is the fact that natural (biogenic) compounds such as aldehydes, terpenes or acetic acid are outgassed from wood - intensified by the technical processing of materials - which can be recognised, for example, by their typical odour. These outgassings can only be influenced to a limited extent by the manufacturers of wood-based materials and are essentially caused by the natural properties of the different woods.

The health relevance of these outgassings is scientifically debatable. While some demand the lowest possible pollution of indoor air with volatile substances for precautionary reasons, others point to the low toxicity of these biogenic substances and argue that mankind has been living with these emissions for a long time. This discussion was intensified by the new state building codes (LBOs) in Germany, based on the model building code MVV TB, which prescribe an emission test for wood-based materials in order to designate them as suitable for construction. After the industry successfully sued against this in individual federal states, the corresponding section of the LBOs is currently not applied to wood-based materials. In any case, the fronts have hardened quite a bit and timber construction in Germany is facing yet another barrier on this issue.

natureplus in conflict

For natureplus, the situation is tricky in two respects: on the one hand, we want to support timber construction for environmental and climate protection reasons; on the other hand, we see ourselves as strictly committed to science with our ecolabel and avoid simplifications of the "nature is healthy" kind. In addition, the strict restriction of emissions has been an essential feature of our quality label from the very beginning: our requirements for low emissions, laid down in the award guideline RL5010, are therefore even stricter than the official framework of the AgBB in Germany, amounting to only 30% of it. For numerous sub-substance groups we have formulated our own, even stricter requirements. As a result, the majority of the corresponding manufacturers did not see themselves in a position to meet these requirements, and we were not able to promote timber construction with our eco-label as intended.

The new expert opinion now comes to the conclusion that in many cases the standardised test chamber measurement after 28 days does not correspond to the actual emission behaviour of certain biogenic compounds and it therefore provides unreliable results. In addition, the expert opinion states that there is no evidence to assume an adverse health effect at concentrations far below the LCI values (limit values for toxicity) and therefore proposes a relaxation of the natureplus requirements for certain wood-typical compounds.

What is to change?

As a result, the limit value after 28 days in the test chamber for the sum of volatile organic compounds (TVOC) is to be raised from currently 300 to 1,000 µg/m³ for products made of wood and wood-based materials, and the limit values for the wood-typical biogenic substance groups terpenes and aldehydes are to be raised as follows: for the sum of bicyclic terpenes from 200 to 700 µg/m³ and for the sum of C4-C11 aldehydes (acyclic, aliphatic) from 100 to 200 µg/m³. Some years ago, for the same reasons, the limit value for acetic acid was raised to 600 µg/m³ and this was removed from the TVOC.

We are aware that with this offer to the wood-based materials industry, natureplus is making a compromise compared to its previously very strict stance. Therefore, it is important for us to invite all interested parties, members and partner organisations and also certification organisations that rely on the natureplus label, such as DGNB, BNB, BREEAM and LEED, to discuss and comment on this draft amendment before it formally comes into force. Send us your comments in writing so that we can take them into account. We will also organise a public hearing, probably in the new year, to discuss and weigh up the comments, and we invite you all to attend now.

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