E5-4 – Resource Inflows

The main resource inflows associated with our operations relate to construction products and building materials used in new construction, modernization and maintenance. They include, for example, concrete, steel, stone, insulation materials, windows, roof tiles, tiles, plaster and other finished construction products made of plastic, ceramics and metal. The most important biological building material is wood. As Vonovia is the client, and not the executing company, in the area of development/new construction, it does not purchase the building materials and products used itself. Our contractors generally purchase building products through retailers, or directly from manufacturers. Modernization and maintenance work is carried out either by the company’s own technical service, Vonovia Technischer Service GmbH, or by subcontractors. In both cases, the building materials tend to be purchased via retailers. Information on the proportion of biological materials from sustainable sources and the quantity of recycled materials is kept in the upstream value chain and is not usually communicated along with other product specifications. To date, Vonovia has neither imposed requirements on subcontractors and retailers regarding these aspects nor has it requested information in a structured and systematic manner. This is why, at the level of our own operations, the information required to verify sustainably sourced biological materials and reused or recycled secondary components, products and materials is not available to us. Vonovia plans to implement suitable procedures for obtaining this information in the future.

The resource inflows in new construction are calculated using an in-house Excel tool for the integrated calculation of greenhouse gases, primary energy requirements, mass and circularity (ÖBIGK) throughout the life cycle, which calculates the various parameters using a reference house approach. This involves determining the structural components and their corresponding mass based on the type of construction and the areas on which the project is being implemented (above ground and underground). The total mass of a project is allocated to the year in which the project was completed, even if the building was constructed over more than one period. This ensures consistency with general reporting and GHG accounting.

As far as data on mass in connection with modernization and maintenance is concerned, the data taken as a basis includes the service items invoiced in Germany and recorded in the system in the reporting year. This information is used to define those service items that, according to criteria including the type of service, number of entries per service item in the reporting year and minimum weight per unit, involve a significant inflow of resources. The weights of the materials used were obtained from manufacturer specifications or comparable reference products, e.g., from the ÖKOBAUDAT platform provided by the Federal Ministry of Housing, Urban Development and Building (BMWSB). Services that were not invoiced using unique service numbers were extrapolated using product category-specific factors. The data for Austria and Sweden was extrapolated based on the assumption that new construction and modernization work is carried out in the same way and using the corresponding investment volumes.

The data calculated, in particular for modernization and maintenance, is based on a series of assumptions and contains a significant share of extrapolations and estimates based on reference products and average weights per product category. Although this method creates a certain degree of uncertainty, it represents the best possible approximation, with reasonable outlay, given the variety of materials used. Due to the component-based reference house approach, the model house calculation reveals a higher degree of accuracy for new construction resource inflows than the data on modernization.