Resource efficiency in the construction industry
The construction industry is one of the most resource-intensive industrial sectors worldwide. In Germany alone, 550 million tonnes of mineral raw materials are used in construction every year. This is equivalent to 85% of the entire domestic extraction.1 The annual use of structural steel (5.5 million tonnes) and cement (28 million tonnes) is also considerable.2 This leads to the fact that the building stock in Germany now comprises an estimated 100 billion tonnes of material.3 192 million tonnes is taken out of the building sector in construction and demolition waste - equivalent to 54% of the total waste produced in Germany.4 At the same time, this enormous raw material deployment contains huge saving potentials and this why the construction industry plays a key role in the implementation of resource efficiency.
In this context, resource efficiency means both energy and material efficiency. Energy efficiency has already been intensively discussed in energetic building renovation. There is considerable need for action here since one third of German final energy consumption is required for heating and hot water generation.5 Since the energy requirement adds up over many years due to the long service life of most buildings, high priority must be given to the topic of energy consumption per square metre of usable area. Investigations carried out by the VDI Centre for Resource Efficiency show that this aspect of building insulation can be connected with the use of resource-saving materials many times over. This will not only reduce energy consumption over the usage phase in the long-term, but will make it possible for energy requirements and CO2 emissions to be sustainably reduced as early as the insulation manufacturing phase.
Energetic building renovation is, however, highly recommended for another reason under resource aspects. The material requirement of a renovation project is two thirds less than that of a new building.6 For this reason, renovation should be preferred to new construction wherever possible, and this is also important with regard to the required reconstruction of the building structure to meet the requirement for age-appropriate residence. In the case of new "green-field" construction projects, the additional area required in addition to the greater raw material consumption for the newly constructed infrastructure (roads, sewers, public facilities etc.) can additionally be assessed as negative. For this reason the utilisation of already developed areas through the re-utilisation of derelict areas, re-densification and increasing the number of storeys should be given priority in the sense of resource-optimised construction.
The construction industry also offers huge efficiency potentials due to the mass flows demonstrated above with a view to material efficiency – something which has hardly been dealt with in the media. Investigations carried out by the VDI Centre for Resource Efficiency show how resource utilisation can be reduced by supporting structures. In addition to the selection of resource-conserving materials, the use of recycling concrete can play an important role. This is because it uses recycled aggregates as an additive and therefore reduces the excavation of primary rocks, such as gravel.
1 Keßler, H., 2011: Urban Mining – Ressourcenschonungspotenziale einer hochwertigen Nutzung des anthropogenen Lagers im Gebäudebestand, Tagungsband zum 23. Kasseler Abfall- und Bioenergieforum, Hrsg. Witzenhausen-Institut, S. 1
2 Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit (Hrsg.): Deutsches Ressourceneffizienzprogramm (ProgRess), Mai 2012, S. 73
3 Schulze-Darup, B. (Hrsg.): Energetische Gebäudesanierung mit dem Faktor 10, Deutsche Bundesstiftung Umwelt (DBU-Projekt AZ 19208), S. 5
4 Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit (Hrsg.): Deutsches Ressourceneffizienzprogramm (ProgRess), Mai 2012, S. 73
5 BDEW: Endenergieverbrauch in Deutschland 2007, Berlin, 12/2008, S. 10
6 Umweltbundesamt (Hrsg.): Rohstoffeffizienz – Wirtschaft entlasten, Umwelt schonen, November 2010, S. 8