Urban climate concept

The urban climate concept provides an in-depthassessment of the climate and immission-ecological functions of the city of Jena. However, the urban climate concept is not only intended to assess the current state of the climatic situation, but also to focus on planned structural changes.The urban development department is currently updating the city of Jena's land use plan. The urban climate concept is intended to evaluate the planned development areaswith regard to their expected impact on the urban climate and providerecommendations for the structural implementation of the individual development areas.

A spatially delimited urban climatic assessment (cold air, heat load) is to be carried out in planning information maps and, as a result , concrete planning recommendations for improving or maintaining the local climatic situation for individual spatially delimited areas are to be derived .

Ultimately, the knowledge gained must be translated into municipal action. A key focus of the urban climate concept is therefore the instrumental implementation and anchoring of the necessary measures in planning law. Concrete proposals for (quantifiable) specifications, requirements and stipulations as well as possible instruments for their implementation are to be submitted. In particular, the possibility of specifying concrete legal stipulations in development plans will be examined in detail.

The project is divided into the following project modules.

1. urban climate modeling and climate analysis

Urban overheating continues to increase in Jena as a result of increasing inner densification due to high utilization pressure on limited space and global climate change. In the interests of climate-resilient urban development, it is necessary to evaluate the areas in terms of their climate characteristics and climate function. This evaluation then forms the basis and argumentation aid for the assessment of building developments, for the development of optimization proposals and for securing areas.

In a first step, a three-dimensional, spatially high-resolution urban climate modeling with FITNAH-3D is carried out, which depicts both the current use and green structure and reflects various land use and climate change scenarios. The approximately 195 km² study area is modeled in a horizontal grid of 10 m over 24 h (time step: 10 seconds). This forms the basis for the qualitative and quantitative assessment of the climate-ecological process of cold air and the overheating situation or the human bioclimatic stress situation for day and night.

The urban climate analysis is carried out for three scenarios in the target period up to 2035:

Scenarios Urban climate analysis up to 2035

In the next step, individual maps of key urban climate parameters are derived from the three high-resolution model calculations. These include the ground-level temperature and wind field, the cold air volume flow, the cold air production rate (night) and the perceived temperature (day), in each case for the current situation and the two future scenarios. This individual climatic information is then combined in six synthetic climate analysis maps (one for each scenario), one for the day (14:00) and one for the night (04:00).

2. assessment and planning information maps

In this project module, the present climate analysis is evaluated. This evaluation is based on VDI Guideline 3785 Sheet 1, which uses evaluation categories to identify the favorable and unfavorable factors of a location and to derive specific action and planning requirements. The assessment criteria include climate function, spatial location, value characteristics, area size and area type.

The urban area is divided into impact areas (settlement/transport areas) and compensation areas (green/open spaces) and assigned to a corresponding assessment category (very favorable to very unfavorable or very high to very low climatic significance) using an algorithm or the so-called z-transformation. This assessment is carried out for the day and night situation in all three scenarios. As a result, 6 assessment maps are available for the urban area.

The assessment maps form the basis of the planning information map on the urban climate. The planning information map is to be developed as an important basis for the consideration of climatic issues in preparatory and binding urban land-use planning and to provide concrete recommendations for action to maintain a pleasant urban climate (bioclimate) or to improve unfavorable climatic conditions. The aim is to maintain the quality of life within the meaning of Section 1 (5) BauGB and to maintain healthy living and working conditions within the meaning of Section 34 BauGB in the city while at the same time developing the location of a regional center in line with demand.

The development areas of the FNP update are taken into account in the planning information map. An individual climatic assessment of the cold air situation and heat load is carried out for each development area in a fact sheet. In accordance with the area assessment, recommendations are made on the extent of development, building position, street and building greenery, rainwater (use, infiltration, storage, evaporation), unsealing and the choice of materials for buildings and infrastructure (heat input, heat storage).

3. instrumental implementation

With the aim of anchoring the knowledge gained and the recommendations for action based on it from the planning information maps in planning law and transferring them to implementation, the urban climate concept will conclude with an in-depth examination of instrumental implementation. Here, the instruments of formal planning, i.e. preparatory and binding urban land-use planning, will be the focus of consideration.

All measures that are mentioned in the planning information maps and serve to optimize the urban climate will be examined with regard to the existing possibilities for anchoring them in planning law and assigned to suitable planning instruments. Concrete proposals are to be drawn up as to which - in particular quantifiable - requirements, conditions, stipulations etc. can best be implemented using which instruments.

The project is being led by the urban development department and supported by the external expert Geonet umweltconsulting GmbH from Hanover. An internal administrative project group was also established for the development process.

The project is funded proportionately (40%) by the Thüringer Aufbaubankas part of the "Klima Invest" funding program.The funding is aimed at achieving the objectives of the Thuringian Climate Act, in particular the reduction of greenhouse gas emissions and adaptation to the unavoidable consequences of climate change in Thuringia.