Background and issues
Public squares are a central design element of a city and of great importance for the living quality in the city. Their design regarding sealing grade, buildings and infrastructure and moreover vegetation can vary tremendously. In many cases, public squares are heavily frequented areas within the city center and have often very different effects on the individual and thermal wellbeing of humans due to their diverse structural elements.
The design of public open spaces is in the context of the urban heat island effect and the consequences of climate change a central issue of city planning. Especially public squares should be designed attractive for humans and moreover foster the thermal wellbeing of humans. For this, urban green can contribute by provision of so called ecosystem services such as shading, cooling, humidification, wind buffering, promotion of biodiversity and aesthetic.
At this point of green space planning and research works the project "Ecosystem Services of Urban Green at Public Squares in Munich". The project will record the available urban green at selected squares in Munich and quantify their ecosystem services. For this, two different modelling approaches will be used on the one hand to calculate the regulative services by carbon storage, cooling effects and shading (with the process-based growth model CityTree, see project "City Trees II") and on the other hand analyse the effect of vegetation on the thermal wellbeing of humans in high temporal resolution (high resolution climate model ENVI-met, see project "Urban Green Infrastructures"). Moreover, at chosen days (hot days, cool days) the services of vegetation will be measured exemplarily as well as different design scenarios will be tested in view of climate change. With these approaches, recommendations for a future sustainable and efficient design of built-up areas and urban green at public squares can be provided.
The planning and design of public squares, especially of urban green, is so far mostly following aesthetic basics and less the expected services provided by vegetation. However climate change poses severe problems, the thermal comfort of humans is often inadequate at heavily sealed with dense built-up areas and heavily frequented squares and can lead to significant health problems.
Climate scenarios predict a decrease of the living quality in cities due to more hot days and warm periods as well as changed precipitation patterns. A change in the design of public squares to higher thermal comfort is therefore necessary for a climate adapted city of the future. In this interdisciplinary project the services of present urban vegetation at chosen squares in Munich for recent climate parameters will be compiled and the effect on the thermal comfort of humans will be shown. Moreover, with climate models and several different design scenarios, future possibilities for the design of public squares in view of climate adaptation will be developed. These findings will be assessed within the context of the ecosystem services of vegetation, the thermal comfort of humans as well as the aesthetic of the squares.
With two modelling approaches, the services of urban green infrastructures under current climate conditions and built-up areas (especially the sealing degree) as well as the effects of changes for climate and structural elements of the squares simulated. In a further modelling approach it will be tested, how different design scenarios affect the thermal comfort of humans at the squares to gain knowledge for future space design. These findings will be tested at selected days (hot days, cold days, cloudy days) and for different squares and green infrastructures. Finally the results will be combined with the results of the project Places:M to further consider the feelings of humans.
Based on these knowledge gaps the project will assess the following objectives:
- Q: Which contributions are performed by green (trees, hedges, grass) at public squares in Munich for the cooling of air temperature, the decrease of rainwater runoff and the carbon storage in relation to plantation clusters (trees - hedges, dense foliated - sparse foliated, young trees - old trees)?
- Q2: How to the ecosystem services of vegetation (trees, hedges, grass) of an public square in Munich change under changed climate conditions (increase in temperature, changed precipitation patterns)?
- Q3: How can the selected squares be adapted to climate change (cooling by transpiration, decrease of runoff, increase of carbon storage), e.g. by different tree species, planting density, etc.?
- Q4: How are the climatic conditions of selected squares on single days? Can optimizations of the site climate conducted by vegetation (trees, hedged, grass)?
All analysis to answer the objectives of the project will be conducted at selected squares of the ZSK subproject "100Places:M" in Munich. Out of the total number of squares will be 20 squares selected, which are representative for different square types concerning location within the city, geometry and usage as well as planting types. The selection will be based on the database of the project 100Places:M about the analysed squares in Munich and in close cooperation with the researchers of 100Places:M. Time-intensive measurements such as the modelling of squares with ENVI-met will likely be conducted on a part of the selected squares (up to 10 squares), which will also be representative for Munich regarding their features, geometry and location.