Private households consume about 30 % of Germany's total primary energy and cause about 15 % of the total CO2 emissions, and so this sector represents a key sector for climate protection targets. Whereas primary energy consumption in buildings is limited by regulations, the production of carbon emissions‐intensive materials is only moving slowly into the focus of legislation, regulations and, ultimately, the perception of society. Considering a thermally conditioned building during its life cycle, most environmental effects are during operation. Nevertheless, the grey energy of a concrete structure can add up to 20 % in individual cases. Owing to the carbon‐intensive cement production, concrete as a material causes relatively high environmental impacts. Logical options appear to be substituting cement with so called by‐products or using recycled additives. In fact, there are only a few projects that have used a resource‐saving concrete. In 2010 in Ludwigshafen, one building in a group of buildings was chosen as the first building in Germany to be built almost completely from recycled concrete without increasing the cement content. It was built as a low‐energy construction and in a zero‐carbon‐emissions area. The project was supported scientifically by the Institute of Energy and Environmental Research in Heidelberg and the Brandenburg University of Technology Cottbus. The buildings won the Construction Prize 2011 with the distinction “best relation between quality and costs”. This paper discusses integral aspects of the use of recycling concrete from the structural design, eco‐accounting and materials properties perspectives. It demonstrates the potential and opportunities for the quality‐assured use of recycling concrete for sustainable resource management.
Resource management is becoming increasingly important in the construction sector. In order to support the recycling of materials, it is necessary to determine the quantities in the building stock and those caused by construction activities. At present, a large number of different actors use different categories for construction materials and the raw materials they consist of as well as for waste categories, depending on their field of activity. This results in imprecisions that make it difficult to consistently track and influence mass flows and hinder targeted resource management. This is the starting point of this paper as it discusses possibilities to establish a consistent allocation of materials to context-typical groups following the approach of continuous material flow analysis. On the input-side, aspects of mineral planning and on the output-side aspects of waste and secondary raw material management are being considered and references to grey emissions are established along the entire process chain. In this way, cross-departmental planning relating to recycling management and climate protection will be supported. With regard to the object of consideration and the level of action, a distinction is made between two different spatial scale levels: on the one hand, the individual building level, where the material inventory approach is used to provide detailed information on the building’s material composition, and on the other hand the regional level, for which more aggregated information on building material groups is provided in the form of material cadastres. Current results of a research project in Germany are presented.
The built environment is the cause of most of the material flows in the anthroposphere and the biggest material storage: Over 90 % of the anthropogenic stock stored in durable goods can be found in the built environment, with non-metallic minerals being the main contributor. In Germany, most of the materials that leave the stock due to demolition or renovation are recovered. In Saxony, a German state, the recovery rate is nearly 99 % but only 55% of mineral construction and demolition waste is recycled. There is still substantial potential for closing recycling loops. This requires the combined effort of all those actors that influence these material flows – from the investor and constructor of the single building to those responsible for waste management at municipal level and the waste disposal and construction materials industry. However, the information currently available is insufficient to support an effective urban mining. This will be encountered by an ongoing research project that aims to enhance existing informational instruments regarding construction related material flows in the built environment. The project follows a dualistic research approach considering informational instruments at (1) individual building level and (2) at regional level. The objective of the paper is to present an approach on how material inventories can be better aligned with practical information needs. After introducing the overall concept and methodology as well as describing the process of analysing the current state of information flows, first results considering the structure of material in- and outputs and the needs for information of different actors are presented.
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