Point of Departure
The results obtained through the use of the climate model FITNAH have permitted a comprehensive stock-taking of the current climatic situation in the area of the city of Berlin and its immediate surroundings (cf. Map 04.10 Climate Model Berlin – Analysis Maps, 2009 Edition.) In Phase II, this information was used as the basis for evaluation maps (cf. Map 04.11 Berlin Climate Model: Evaluation Maps, 2009 Edition). One essential appraisal factor for an overall assessment relevant for planning is the human bio-climate.
The most frequent application for the determination of possible heat load on the human organism is the scaled evaluation quantum Predicted Mean Vote (PMV), the value with which an assessment of the thermal surroundings is indicated. More detailed instructions for the application of the method are VDI Guideline 3787, Part 2, “Methoden zur human-biometeorologischen Bewertung von Klima und Lufthygiene für die Stadt- und Regionalplanung” (methods for the human bio-meteorological assessment of climate and air hygiene in urban and regional planning), which reflects the current state of scientific findings, and recommends this method as the standard application (VDI 1998).
The classification and legend classification of the bio-climatic load potential of a summer nocturnal radiation period is oriented towards the standardisation procedure for Z-transformation, as described in VDI Guideline 3785, Part 1 (VDI 2008). This statistical procedure is generally based on the local/ regional level of values of a climate analysis, and assesses the deviation of a climate parameter from the mean conditions in an investigation area. The VDI guideline defines four evaluation categories (very favourable/favourable/less favourable/unfavourable), on which the classification of the model results is to be oriented.
In future, an essential further methodological development can be expected when the Universal Thermal Climate Index (UTCI), a project currently being developed at the European level, is presented as the “state of the art”.
As a basis for the ascertainment of bio-climatic load, a Z-transformation of 50 m*50 m PMV result grid was established. For this purpose, the PMV at 4 a.m. was used, which has proved the best suitable time for the assessment of bio-climatic load in residential areas. Due to the heterogeneity of the model area, this point in time represents a compromise between the situation in an inner-city area on the one hand and the peripheral districts on the other.
The load classes correspond to the four categories as per VDI Guideline 3785 (unfavourable/less favourable/favourable/very favourable) (cf. Table 1)
The Load Class 4 “unfavourable” represents a case of above average thermal pollution with a Z value of more than 1. A certain level of bio-climatic load is also present in case of Load Class 3, “less favourable”. In the cases of Classes 2 and 1, on the other hand, favourable conditions prevail, which can be evaluated as positive from a bio-climatic viewpoint.