Vergabeentscheidung und Wirtschaftlichkeitsberechnung von PPP/PFI‐Projekten in der Bauwirtschaft

Contract letting and economic calculation of PPP/PFI projects in construction industries. Risk premium has to be taken into account in the PPP comparison of producti‐vity. In case of PPP/PFI projects, officials compare the costs of self construction to the costs of leasing from private investors (PSC calculation). In this context, risk factors for two different variants (A, B) are calculated using both the DCF method and the VaR approach. Finally, the economic results for each PPP party and the expected yield are discussed.     

The influence of temperature on nutrient treatment efficiency in stormwater biofilter systems.

Nutrients can cause eutrophication of natural water bodies. Thus, urban stormwater which is an important nutrient source in urbanised areas has to be treated in order to reduce its nutrient loads. Biofilters which use soil filter media, biofilms and plants, are a good treatment option for nutrients. This paper presents the results of a biofilter column study in cold temperatures (+2 degrees C, +8 degrees C, control at +20 degrees C) which may cause special problems regarding biofilter performance. It was shown that particle-bound pollutants as TSS and a high fraction of phosphorus were reduced well without being negatively influenced by cold temperatures. Nitrogen, however, was not reduced; especially NO(x) was produced in the columns. This behaviour can be explained with both insufficient denitrification and high leaching from the columns.     

Nutzungskosten: DIN 18960-2008 – Leistungsfähige Grundlage für die zielorientierte Planung der Lebenszykluskosten

User costs of buildings DIN 18960 – a performance basis for planning of life cycle costs. An updated version of the DIN 18960 – user costs of buildings – has been published in February 2008. The norm has been further developed with supplements to a comprehensive controlling concept (usage cost estimate, usage cost calculation, usage cost monitoring and usage cost management), which provides the builder with the tools to plan the usage costs in a cost-controlled manner. This norm, furthermore, provides an economically and ecologically important basis for the planning process. The new aspects of the DIN 18960 are outlined, the related norms and important features are explained, the controlling concept including a calculation example that considers risk factors is described and questions regarding planning contracts are discussed.