Research Area:
Resource Efficiency of Settlement Structures


Energy and material flows from production to the consumption site of secondary materials from the building sector for the construction sector

The recycling of construction waste is an important stepping-stone towards the achievement of resource conservation and the reduction of environmental impacts through construction. Within the federal programme ProgRess II, it was decided to add an energetic perspective to the use of natural material resources in order to develop synergies as well as to reveal likely conflicts in aims. This also applies to the consideration of secondary raw materials. However, it has not yet been clarified how to implement such an combined analysis.

Photo: IOER-Media
Collage with three photos

Aim of the project

The aim of the research project was to extend material-oriented investigations on resource conservation potentials by energetic considerations and to develop an approach that allows the calculation and evaluation of energy consumption of recycling processes.

Results so far achieved

A method was developed which allows a uniform evaluation of different building products with regard to the energy consumption resulting from their production from construction and demolition waste. This was specified by means of the following building products as examples: Concrete, bricks, sand-lime bricks, gypsum, flat glass, mineral insulation materials, plastic profiles, other plastic, petroleum-based insulation materials and timber.

The method describes a sequence of three steps: Two steps for calculation of process energies for (a) the processing of demolition material to secondary material and (b) the conditioning of the secondary material to recycling material (substitute) with the same quality as corresponding products made by natural material. In the third step, the evaluation is carried out by comparing the process energies of construction products with recycled material with corresponding construction products made of natural materials.

Results indicate that recycled construction products can often be produced with less energy, in some cases with significantly less energy (e.g. plastics). This statement cannot be made with the same clarity for mineral materials. Depending on the type of application, recycled products are energetically advantageous (e.g. bricks, sand-lime brick), are of similar dimensions (e.g. concrete, flat glass) or require a higher energy input to produce (e.g. plasterboard, rock wool).

An evaluation of the energetic advantages of recycling products is therefore only reliably if the recycling process chains from demolition material to recycled material in new application are considered as a whole. The findings provide parameters for the implementation of continuous material flow analyses and the evaluation of cycle-oriented business models with regard to the associated raw material and energy saving potentials as well as - under consideration of life cycle assessment - CO2 saving potentials.




Dr.-Ing. Georg Schiller 
Phone + 49 351 4679 259

Dipl. Ing. (Arch)
Karin Gruhler

Phone +49 0351 4679 250
(Projectmanagement, modelling of the mass and energy approach)


Bundesinstitut für Bau-, Stadt- und Raumforschung (BBSR)


Dipl.-Ing. J. Reichenbach, INTECUS GmbH (Waste Management and Environment-Integrating Management, Dresden)


Final report