Calculation of EPD for individual AAC product classes

In fact, climate change is increasing the relevance of Environmental Product Declarations (EPDs). Currently, product‐specific EPDs are coming into vogue instead of average‐based EPDs. Individual EPDs for distinct products can be beneficial, but the data preparation upfront is crucial to avoid greenwashing through the use of false data. Adjustments to the standards for calculating EPDs are currently under development.

The starting point for the calculation of EPD according to EN 15804+A2 is always the annual production and associated consumption of raw materials and energy. The raw material input per product is calculated from recipe data and the respective production quantities as a first step. This shall be done for all products of a plant. Now, the summarized consumptions have to be related with the purchased raw material quantities, correction factors have to be calculated and applied to specify the actual input per product. The use of correction factors is mandatory to avoid inaccuracy and underestimation of actual consumption. Hence, the calculation of one product‐specific EPD requires product‐specific source data preparation for all products.

In AAC production, the correction of the consumed raw materials is particularly important concerning internal recycling. For example, the actual consumption of aluminum is of specific interest. While ground sand within the recycled sludge is unchanged and binders still react in the autoclave, the aluminum is no longer reactive. This can lead to additional aluminum consumption that deviates by one‐third and more from the recipe values.

In the presentation, a comprehensive approach to the calculation of correction factors for different AAC product classes will be introduced. The final calculations for the EPD are not based on recipe data alone but are corrected using procurement data. Thus, the total consumption of a plant can be adequately allocated to all products in the production program.