Material stocks in Germany's non-domestic buildings: a new quantification method

Abstract

The building sector consumes large quantities of resources and generates high levels of construction and demolition (C&D) waste. From an ‘urban mining’ perspective, the building stock can be seen as a repository of natural resources. In order to manage this repository, evidence is needed on its quantity and dynamics. Although data exist for domestic buildings, little evidence exists for non-domestic buildings. A new method is presented to quantify the material stock of non-domestic buildings – based on the German building stock. The quantification process involves three steps: (1) material composition indicators (MCIs) are calculated with respect to various building types; (2) the country's total floor space is estimated and disaggregated; and (3) the total material stock is calculated. The main results are MCIs and the floor space for both domestic and non-domestic stocks, as well as the material mass in total. In Germany the total material mass of non-domestic buildings is approximately 6.8 billion tonnes, accounting for 44% of the entire building stock. The method can be adapted and validated for use in other countries. These results will assist both policy-makers and the construction industry to understand the potential for moving toward a more circular economy.

Keywords:

• building stock
• fixed assets
• material composition indicators
• material flow
• non-domestic buildings
• resource efficiency
• urban mining

Notes

1 Type 1 buildings are: office and administrative buildings, institutional buildings (i.e., hospitals, nursing or boarding homes); Type 2 buildings are all other non-domestic buildings not included in type 1 (i.e., agricultural, factory, trade and warehouse buildings, hotels, restaurants, cinemas, museums, kindergartens, schools, and sports halls).

2 The references in Table 2 are grouped according to the reference area (international, European, regional studies); the order in each group is chronological.

3 The year 1950 was the last time that a census was undertaken of West Germany's non-domestic building stock. No census data exist for East Germany's non-domestic building stock.

4 Germany's national accounts (Volkswirtschaftliche Gesamtrechnung – VGR) (Destatis, 2012a) are included in the federal statistical yearbooks (Statistische Jahrbücher des Bundes) (e.g., Destatis, 2011c).

5 GISs are information systems used to capture, process, organize, analyze and present spatial data.

6 The German statistics defines ‘new buildings' as the new construction of buildings, excluding repair and restoration works in existing buildings. Data are available for all Germany since 1991.

7 Density parameters (mass per volume) of the different materials were obtained from ÖKOBAUDAT (2014), DIN 4108-4 (2013) and datasheets from manufacturers.

8 Defined according to the definition of synthetic building elements.

9 Corresponding basic assumptions also form the basis for the determination of the gross stock of fixed assets, expressed as a replacement cost, in the national accounts.

10 Floor space = net floor area of the total non-domestic building stock (heated and unheated).

11 Deilmann et al. (2013) give values for net floor area (Nettogeschossfläche), which are converted to floor space area by applying a factor of 0.85.