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Viability of public spaces in cities under increasing heat: A transdisciplinary approach

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Cities are particularly sensitive to the effects of climate change, causing an increasing incidence of heat waves. Extreme temperatures can impair the use of public spaces in cities, as heat stress endangers human well-being and health. Identifying suitable adaptation measures to maintain the full functionality of public spaces requires a multidimensional approach, accounting for interrelated scientific, social, and practical aspects. As one result we introduce an inter- and transdisciplinary concept that addresses the challenge of adapting public spaces to climate change. Additionally we present a pilot study from Heidelberg, Germany, where a new, sustainable urban quarter experienced more pronounced heat stress than the historic city centre in the hot and dry summer of 2018. The study shows the suitability of our approach to identify appropriate heat adaptation measures. Solar potential modelling and mental map surveys proved to be particularly effective methods. We find that adaptation measures generate synergy effects by improving both climatic and social conditions.
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Viability of public spaces in cities under increasing heat: A
transdisciplinary approach
Kathrin Foshag, Nicole Aeschbach, Bernhard H¨ofle, Raino Winkler,
Alexander Siegmund, Werner Aeschbach
PII: S2210-6707(20)30202-X
DOI: https://doi.org/10.1016/j.scs.2020.102215
Reference: SCS 102215
To appear in: Sustainable Cities and Society
Received Date: 21 October 2019
Revised Date: 9 March 2020
Accepted Date: 17 April 2020
Please cite this article as: Foshag K, Aeschbach N, H¨ofle B, Winkler R, Siegmund A,
Aeschbach W, Viability of public spaces in cities under increasing heat: A transdisciplinary
approach, Sustainable Cities and Society (2020),
doi: https://doi.org/10.1016/j.scs.2020.102215
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© 2020 Published by Elsevier.
Viability of public spaces in cities under increasing heat: a transdisciplinary ap-
proach
Authors:
Kathrin Foshaga,b,c (Corresponding author)
kathrin.leutz@iup.uni-heidelberg.de
a TdLab Geography, Institute of Geography, Heidelberg University, Im Neuenheimer
Feld 368, 69120 Heidelberg, Germany
b Institute of Environmental Physics, Heidelberg University, Im Neuenheimer Feld 229,
69120 Heidelberg, Germany
c Heidelberg School of Education, Heidelberg University, Voßstraße 2, Building 4330,
69115 Heidelberg, Germany
Nicole Aeschbacha,g
nicole.aeschbach@uni-heidelberg.de
a TdLab Geography, Institute of Geography, Heidelberg University, Im Neuenheimer
Feld 368, 69120 Heidelberg, Germany
g Heidelberg Center for the Environment (HCE), Heidelberg University, Im Neuenheimer
Feld 229, 69120 Heidelberg, Germany
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Bernhard Höfled,g
hoefle@uni-heidelberg.de
d 3D Geospatial Data Processing (3DGeo) Research Group, Institute of Geography,
Heidelberg University, Im Neuenheimer Feld 368, 69120 Heidelberg, Germany
g Heidelberg Center for the Environment (HCE), Heidelberg University, Im Neuenheimer
Feld 229, 69120 Heidelberg, Germany
Raino Winklere
raino.winkler@heidelberg.de
e City of Heidelberg, Office of Environmental Protection, Trade Supervision and Energy,
Prinz-Carl, Kornmarkt 1, 69117 Heidelberg, Germany
Alexander Siegmundf,g,h
siegmund@ph-heidelberg.de
f Department of Geography Research Group for Earth Observation (rgeo) & UNESCO
Chair on World Heritage and Biosphere Reserve Observation and Education, Heidel-
berg University of Education, Czernyring 22/10-12, 69115 Heidelberg, Germany
g Heidelberg Center for the Environment (HCE), Heidelberg University, Im Neuenheimer
Feld 229, 69120 Heidelberg, Germany
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h Institute of Geography, Heidelberg University, Im Neuenheimer Feld 348, 69120 Hei-
delberg, Germany
Werner Aeschbachb,g
aeschbach@iup.uni-heidelberg.de
b Institute of Environmental Physics, Heidelberg University, Im Neuenheimer Feld 229,
69120 Heidelberg, Germany
g Heidelberg Center for the Environment (HCE), Heidelberg University, Im Neuenheimer
Feld 229, 69120 Heidelberg, Germany
Highlights
Integrated transdisciplinary set of methods to co-design climate change adapta-
tion.
Heat adaptation measures for public squares in Heidelberg, Germany.
Measures have a regulating effect on the microclimate and increase well-being.
Local actors are indispensable partners in transdisciplinary projects.
Abstract
Cities are particularly sensitive to the effects of climate change, causing an increasing
incidence of heat waves. Extreme temperatures can impair the use of public spaces in
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cities, as heat stress endangers human well-being and health. Identifying suitable adap-
tation measures to maintain the full functionality of public spaces requires a multidimen-
sional approach, accounting for interrelated scientific, social, and practical aspects. As
one result we introduce an inter- and transdisciplinary concept that addresses the chal-
lenge of adapting public spaces to climate change. Additionally we present a pilot study
from Heidelberg, Germany, where a new, sustainable urban quarter experienced more
pronounced heat stress than the historic city centre in the hot and dry summer of 2018.
The study shows the suitability of our approach to identify appropriate heat adaptation
measures. Solar potential modelling and mental map surveys proved to be particularly
effective methods. We find that adaptation measures generate synergy effects by improv-
ing both climatic and social conditions.
Keywords: Climate change adaptation; Urban climate; Urban environment; Trans-
disciplinary sustainability research; Heat stress; Public places; Health improve-
ment
1. Introduction
Climate change and adaptation to climate change are among the major challenges of our
time (Intergovernmental Panel on Climate Change, 2014; Rüegg, 2019; United Nations,
2015). The increase in the number and severity of heat stress events in cities requires
the urgent development of adaptation measures in order to protect the health and well-
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being of inhabitants as well as the social function of public places in future sustainable
cities (cf. Sustainable Development Goals 3 and 11, (United Nations, 2015). There is
extensive evidence that anthropogenic climate change, both observed and modelled,
continues to raise the frequency and intensity of extreme heat events, especially in urban
regions and their public areas (Bastin et al., 2019; Christidis, Jones, & Stott, 2014; Russo,
Sillmann, & Fischer, 2015; Schär, 2015; Tomczyk & Bednorz, 2016; Wang, Jiang, & Lang,
2017; Wouters et al., 2017; Zhao et al., 2018). Heat extremes can be detrimental to hu-
man health, including dehydration, discomfort or exhaustion (de’ Donato et al., 2015;
Keeler et al., 2019; Lafortezza, Carrus, Sanesi, & Davies, 2009; Nikolopoulou & Lykoudis,
2006; Ragettli, Vicedo-Cabrera, Schindler, & Roosli, 2017; Schuster, Honold, Lauf, &
Lakes, 2017; Vogel, Zscheischler, Wartenburger, Dee, & Seneviratne, 2019; Zhao et al.,
2018) and can increase heat-related mortality (de’ Donato et al., 2015; Lafortezza et al.,
2009; Muthers, Laschewski, & Matzaraki, 2017; Ragettli et al., 2017; Rüegg, 2019;
Schuster et al., 2017).
Public open spaces and squares in cities will become increasingly unusable in the future
without successful adaptation measures to the changing climatic conditions (Keeler et al.,
2019; Nikolopoulou & Lykoudis, 2006). Open spaces are important not only for their reg-
ulating effect on the urban climate, but especially for their social aspects and multifunc-
tionality, which is reflected in the diversity of users, styles of design and demands (Castan
Broto & Bulkeley, 2013; Lafortezza et al., 2009; Nikolopoulou & Lykoudis, 2006). Main-
taining the usability of public spaces is crucial for regulating the microclimate in urban
areas and for recreational and leisure activities of city dwellers and visitors (Gehl, 2011;
Nikolopoulou & Lykoudis, 2006; Nikolopoulou & Steemers, 2003). This adaptation is part
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of sustainable urban development to transform cities into attractive and climate-resistant
areas (European Environment Agency, 2016; Nikolopoulou & Lykoudis, 2006). We have
developed a novel integrated transdisciplinary set of methods to co-design climate
change adaptation measures for public places of cities. We found that a successful de-
velopment of measures could only occur with the involvement of the relevant stakehold-
ers: citizens, city planners, experts from research and local experts such as interest
groups, initiatives and city government (Hirsch Hadorn & Pohl, 2007; Lemos et al., 2018;
Pohl, 2008). Developing effective and feasible measures means incorporating physical
parameters, human perception and practical requirements. Measures that have a regu-
lating effect on the microclimate of public squares align with the citizens' suggestions for
changes that would increase their perceived well-being and contribute to sustainable ur-
ban development (Capstick, Whitmarsh, Poortinga, Pidgeon, & Upham, 2015; Lafortezza
et al., 2009; Rosenzweig, Solecki, Hammer, & Mehrotra, 2010). Furthermore, with appro-
priate measures, focused building and planning regulations can enhance the resilience of
cities and spaces to heat stress (Hatvani-Kovacs, Belusko, Skinner, Pockett, & Boland,
2016).
Climate data relevant to (local) decisions, interdisciplinary and transdisciplinary research
approaches, solution-oriented concepts, the identification of co-benefits and closer coop-
eration between the natural and social sciences are some of the requirements for closing
the gap between knowledge and action (Knutti, 2019). With our pilot study, we provide
these impulses and potential solutions for Heidelberg, Germany. Our dataset consists of
climatic and meteorological measurements, modelling of solar potential of current and
future situations at public squares, surveys and mental maps, from which we distinguish
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the effectiveness of the individual methods. Solar potential modelling yielded quantitative
insights on the substantial climatic benefits of specific measures. Standardised question-
naire surveys proved to be significantly less effective and meaningful than mental map
surveys, which allowed a deeper and more interrelated insight into the perception of citi-
zens (Capstick et al., 2015; Lafortezza et al., 2009).
Our methods set is transferable to comparable cities and can be the basis for a sustain-
able (ecological, social and economic) adaptation of public areas to current and future
climate change and the needs of city dwellers. The approach therefore serves as both a
methodological development and as a scientific contribution to addressing challenges in
the context of climate change (Carter et al., 2015). Cities are particularly relevant in this
context as they are at the forefront of climate adaptation with the potential to radiate sus-
tainable development trends to other regions (WBGU, 2016).
1.1 Cities facing climate change
Cities occupy a unique position in anthropogenic climate change (Intergovernmental
Panel on Climate Change, 2014; Wouters et al., 2017)in light of their substantial contri-
bution to CO2 emissions (Moran et al., 2018). Due to their structure and large number of
inhabitants, they are more vulnerable than other regions (McCarthy, Best, & Betts, 2010;
Rosenthal et al., 2007; Wouters et al., 2017). Global climate change and its effects are
expected to intensify in the coming decades, affecting numerous social and biophysical
systems such as population health, urban infrastructure, energy demand and water sup-
ply (Bambrick, Capon, Barnett, Beaty, & Burton, 2011; Bulkeley, 2010; Intergovernmental
Panel on Climate Change, 2014; McCarthy et al., 2010). At the same time, the strong
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global trend towards urbanisation poses increasing challenges to local administrations to
maintain and protect the viability of growing cities and the well-being of their inhabitants
(Rosenthal et al., 2007).
Many factors determine the microclimate in cities and their public spaces (Nikolopoulou
& Lykoudis, 2006). For the well-being of the urban population the bio climate is particularly
important (Mayer, Holst, Dostal, Imbery, & Schindler, 2008; Nastos & Matzarakis, 2008;
Nikolopoulou & Lykoudis, 2006). It describes the totality of atmospheric influences on the
human organism, in particular, thermal influencing factors that comprise short-wave and
long-wave radiation, wind, humidity and air temperature and that have a decisive influ-
ence on human comfort, thermal stress and health (Mayer et al., 2008; Nastos &
Matzarakis, 2008). Increased temperatures and direct sunlight due to a lack of shade are
increasingly causing heat stress conditions in European medium-sized cities such as Hei-
delberg, Germany as climate change progresses (de’ Donato et al., 2015; Muthers et al.,
2017). In general in the mid-latitudes, there is greater thermal stress in summer heat than
in winter cold. This goes hand in hand with the fact that people are generally more ex-
posed to thermal conditions in the summer months than in winter (Mayer et al., 2008;
Müller, Kuttler, & Barlag, 2013; Nastos & Matzarakis, 2008; Nikolopoulou & Lykoudis,
2006).
When adapting cities and public spaces to climate change, solutions must be found that
simultaneously meet the requirements of microclimate, ecology, design, sociology and
economy. These solutions can only be developed on the basis of inter- and transdiscipli-
nary cooperation and by incorporating local knowledge (Adler, Hirsch Hadorn, Breu,
Wiesmann, & Pohl, 2018; Lemos et al., 2018; Leutz, 2018). Through our research we
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have found that it is imperative to overcome disciplinary and institutional boundaries to
make comprehensive use of these approaches.
2. Transdisciplinary research concept
Adaptation to climate change can be viewed as an opportunity to improve the quality of
life in cities. We designed an integrated transdisciplinary set of methods to co-design
adaptation measures and facilitate their implementation (Fig. 1). This design attempts to
grasp the complexity of problems and accounts for the diversity of scientific and social
perspectives. In combining abstract science and case-specific knowledge, concepts that
orientate towards the common good and produces feasible solutions are developed. Co-
operation (co-design) in the development of possible solutions to major societal chal-
lenges at the interface between science and society must integrate the expertise, per-
spectives and knowledge of interest groups (civil society, politics, administration, busi-
ness) into the research process (Lang et al., 2012; Pohl, 2008).
We aim to find a technically effective and publicly accepted solution to keep urban
spaces viable under increasing heat stress. The local stakeholders are indispensable
partners and must be perceived as experts in order to successfully develop and imple-
ment adaptation measures (Adler et al., 2018; Hirsch Hadorn & Pohl, 2007; Pohl, 2011;
Pohl, Krütli, & Stauffacher, 2017).
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The challenges of transdisciplinary research include strengthening the role of non-aca-
demic participants and bridging the gap between knowledge and behaviour at the individ-
ual, social, political and economic levels (Pohl, 2008; Pohl et al., 2017; Strohschneider,
2014).
2.1 Study area
The city of Heidelberg, Germany, is located at 49°25´N / 8°43´E at 114 m a.s.l. at the exit
of the Neckar river valley into the Upper Rhine Graben (Fig. 2). The study area is part of
the Rhine-Neckar Metropolitan Area, a highly urbanised and industrialised area with a
polycentric structure of cities, and with associated climate-ecological stress factors. The
Upper Rhine Graben is traditionally considered a climatically favoured area that is turning
into a particularly vulnerable region in terms of heat stress under global warming. Due to
its latitude protected location within the Upper Rhine Graben, and low maximum altitude
(100-200 m a.s.l.), it regularly reaches higher temperatures than the surrounding areas
(City of Heidelberg, 2015; Fezer, 1977; Leutz, 2018).
The densely built-up areas of the city of Heidelberg are particularly prone to urban over-
heating and a worsening of the climatic situation caused by the current warming (Fezer,
1977; Leutz, 2018). For the comparative microclimatic analysis, the public places “Uni-
versity Square” in the historic (city) center and “Schwetzinger Terrace” in the Bahnstadt,
a modern city quarter, were selected (Fig. 2). Public spaces fulfil a multitude of functions,
including traffic junctions and areas for events, leisure and recreation. They must also be
drained, cleaned and artificially illuminated and should also meet design requirements
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wherever possible. Each function has its own legal and technical framework. The func-
tions can also compete with each other, with competition increasing the pressure of urban
growth and rising land prices. The quality of stay in the area, which is decisive for ac-
ceptance and determined by human bioclimatic factors, is one criterion among many.
The University Square in the centre of the old town has existed since the 18th Century.
The surrounding building complexes and the structure of the old town have also existed
in this constellation for many centuries. In comparison, the Schwetzinger Terrace is a very
young urban development project, which was completed in 2013 as part of the urban
expansion and development of the Bahnstadt district on former brownfield sites. This dis-
trict is characterised by a perforated perimeter block development of passive houses with
loosened inner courtyards and green spaces. The inner courtyards play an important role
in this high density area, opening up the possibility of generating an inner climate that can
create an improvement on a local scale. In addition, individual measures such as green
roofs or water elements (fountains, ponds etc.) have a positive effect on the microclimate
(Leutz, 2018).
3. Methods
Transdisciplinarity (td) denotes a concept of research, organisation and work rather than
as a method or theory in itself. The TdLab of the Department of Environmental Systems
Sciences at ETH Zurich defines transdisciplinary research as an interdisciplinary ap-
proach to scientific inquiry that deals with complex, real-world problems and which places
an emphasis on joint problem framing between people inside and outside of academia
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with the aim of developing possible solutions. Building reflexive collaboration processes,
where researchers can react adaptively to changes in the real-world while working with
project partners, is central to the td approach. (USYS TdLab, 2019).
The process of a transdisciplinary project comprises several phases: Definition and struc-
turing of the object of research, problem solving and knowledge generation, and value
creation, which can trigger transformations in both areas (science and life). The basis of
a transdisciplinary working method and the implementation of results on site is the ex-
change of knowledge and experience between the involved specialist departments and
responsible planning departments within a project (Adler et al., 2018; Cabrera & Cabrera,
2018; Hirsch Hadorn & Pohl, 2007; Lang et al., 2012; Leutz, 2018; Pohl, 2008).
Inter- and transdisciplinary projects typically involve several research groups from differ-
ent fields. Interdisciplinary work requires communication across disciplinary boundaries,
which is often impeded by the diversity of concepts and approaches of the individual sci-
entific cultures. In this project, expertise from physical geography, environmental physics,
human geography and digital geography is represented in the core team with the individ-
ual methods covered by the core team itself. The cooperation with the Environmental
Office of the City of Heidelberg as a stakeholder also builds on a long-standing coopera-
tion. This close integration of all work steps and project participants has made the pre-
sented transdisciplinary approach possible.
The research approach is described in detail below, focusing on the individual methods
drawn upon in this case study.
3.1 Climate science
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Weather stations were installed at two locations for long-term monitoring ambient air tem-
perature and humidity. Standardised weather shelters were used for the measurements
which are ventilated and provide shade for the measuring device inside. At both locations,
these were placed over grass or vegetation at a distance from surrounding buildings (> 5
m) sufficient to mitigate any effects from the buildings themselves. The measuring height
was ~2 m above ground. Mini thermal hygrographs with internal sensors for air tempera-
ture and relative humidity were used. The measuring range for the temperature sensor is
between -20 °C and 50 °C with an accuracy of ± 0.3 °C in the range from 0 °C to 40 °C
(display accuracy 1 digit) and a resolution of 0.1 °C. For relative humidity, the measuring
range is 10 % to 95 % with an accuracy of ± 2 % (display accuracy 1 digit) and a resolution
of 0.5 %. The ambient temperature is measured via a semiconductor or temperature-
dependent resistor with negative temperature coefficient (NTC). In addition, the following
parameters were recorded and evaluated on selected summer days as part of the mete-
orological analyses representative of the urban microclimate at different locations in the
city: air temperature and relative humidity, wind speed and surface temperatures (infrared
radiation) of various materials. Additional digital interface data loggers from Vernier Soft-
ware & Technology (LabQuest 2) and infrared thermometers were used. In order to en-
sure comparability, the measurements were carried out simultaneously under the same
conditions at the different locations. All climate data collected and used for comparison
were evaluated using common calculation and graphics software.
3.2 3D solar modelling
The open source software VOSTOK (Voxel Octree Solar Toolkit) (GIScience Heidelberg
University, 2016) was used for the detailed modelling of the solar irradiation distribution
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in 3D space and over time. VOSTOK simulates the incident solar radiation in 3D point
clouds (i.e. any XYZ coordinates) with a configurable voxel resolution. The tool is based
on the use of the open-source database SOLPOS.H (Solar Position and Intensity) of the
U.S. Department of Energy National Renewable Energy Laboratory to calculate the sun's
position for a specific location during the day and year. CityGML files (City Geography
Markup Language) of the public spaces in Heidelberg serve as 3D scene input for the 3D
solar potential calculation. The first step was to convert the 3D city model into regularly
rasterized 3D point clouds for use in VOSTOK. The shadow cast by the surrounding ob-
jects is modelled using 3D cubes (voxels), which define the environment of a 3D point.
For each location and time step, VOSTOK calculates the solar potential by accounting for
direct and diffuse components under clear-sky conditions, which depend on shadowing
effects of surrounding objects (GIScience Heidelberg University, 2016; Jochem, Höfle, &
Rutzinger, 2011; Liang, Gong, Li, & Ibrahim, 2014; Lin et al., 2017). The resulting file
contains the calculated solar potential for the given locations and time period in watt hours
per square meter (W h/m2), summed for each grid point. In a second step, artificial objects
such as trees can be placed in the 3D scene to quantify the reduction by installing different
design elements. In this way, future development of average shading situations of the
surfaces can be modelled and displayed. Increasing the proportion of green or simulating
a complete state of development of the vegetation reduces the solar irradiation and the
associated heating of the surfaces due to the shading caused. Based on the modelling,
different design and development scenarios of the selected areas can be presented and
measures can be derived (GIScience Heidelberg University, 2016; Jochem et al., 2011;
Liang et al., 2014; Lin et al., 2017).
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3.3 Questionnaire survey
A standardized questionnaire was developed to determine the perception of climate
change and the perception or presentation of public spaces in Heidelberg. This enabled
an identical interview situation to be created for all respondents. The operationalization
and conceptual foundation of the questionnaire is based on a topic-related mind map for
structuring the characteristics and variables in the run-up to the questionnaire conception.
In addition, a targeted literature search was conducted to identify relevant studies, theo-
ries and appropriate scales. For the survey, a pre-test of the questionnaire was conducted
via an online application and discussed in different settings. Based on the pre-test, the
questionnaire modules were modified and finalised, containing both open and closed
questions. The first part of the questionnaire deals with the specific perception of the place
where the survey was conducted. The following data are collected with reference to the
respective location: the way of use, the attractiveness, the positive and negative charac-
teristics, and the assessment and perception of weather conditions. In the second section,
questions are asked about the change in the general urban climate and the importance
of environmental protection. The third section centers on factors that can increase the
attractiveness and quality of stay at a square. The quality of stay refers to the amenities
that public places can provide for the well-being of their users during their stay there. The
questionnaire concludes with the collection of socio-demographic data on the interviewee
(Aschemann-Pilshofer, 2001; Atteslander, 2003; Krosnick, 2018; Nardi, 2018; Rattray &
Jones, 2007). The questionnaire used is included in the supplementary material (A) in a
translated version.
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The survey was conducted as a face-to-face survey with passers-by on several summer
days in 2017 as part of a student’s course. The days of the week, the time of day and the
locations of surveys were varied in order to generate a distribution that corresponds as
closely as possible to a random selection. The sample contains 91 cases, which are
evenly distributed in terms of age and gender. The data were evaluated using descriptive
statistics and SPSS statistics (Supplementary Material; Fig. B1 and B2).
3.4 Mental maps
Perception research deals with the subjective perception of individuals. While the real
environment refers to an assumed materialistic spatial construct that proceeds from an
existing system of order, the relative concept of space refers to a constructivist system of
order that includes elements of communication between individuals and their actions in
space. Each person therefore develops subjective images of reality. This includes not
only urban space, but also its structures and problems. The perceived image of the envi-
ronment is achieved not only through daily indirect or direct contact spaces of an individ-
ual, but above all through personal evaluations, needs and motivations and varies with
age, social status or group membership (Downs & Stea, 1977; Gould & White, 1987).
Individuals typically make subconscious decisions that affect the space or the orientation
in it. These decisions are influenced by how each individual perceives its environment or
how our environment is cognitively represented. In the following, cognitive representation
of space is understood to mean cognitive maps or mental maps. The cognitive maps in
the minds of individuals not only influence their behaviour, but are also subject to constant
change processes due to their own behaviour. Thus, subjective cognitive mapping also
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results in partially distorted, individual inner spatial images of sections and individual as-
pects of the environment (Downs & Stea, 1977; Gould & White, 1987).
Work by Lynch (1960) underpins the application of mental maps used here. A general
formulation of the objectives, planning of the procedure and clarification of the distribution
of tasks in the field should be the starting point of every survey. The interviews took place
in the old town and in the Bahnstadt in Heidelberg. In the first step, open questions were
chosen in order to find access to the method and to obtain an initial assessment of the
respondents' reaction. Paper (DIN A4, white), pens in different colours and clipboards
were provided for the sketches. In addition, the sketchers were allowed to record im-
portant elements for orientation. The survey was carried out in teamwork: while one per-
son spoke with the respondent, a second recorded the course of the conversation and
comments (participant observation). A total of 55 sketches of various public places in
Heidelberg were produced during the survey days. In addition to the resulting sketches,
the dialogues with the interviewees were included in the evaluation. Compared to the
standardized questionnaire survey, the method represents an increase in information and
meets the demand for more realistic models of human behaviour and action and allows
geographical questions to be dealt with at the micro level. The maps and dialogues were
viewed and categorized. The evaluation of the elements presented and the statements
made was carried out by coding and counting. Given that the place of residence can
influence the accuracy of the images, personal information such as the place of residence
and the purpose of the stay in the city were noted (Downs & Stea, 1977; Gould & White,
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1987; Lynch, 1960). In-person questioning allowed spontaneous answers and inter-
viewee thoughts to be recorded. This is especially important when using the mental maps
method. In this way we obtained direct, qualitative data for evaluation.
4. Results and discussion
An interdisciplinary data set was created and the effectiveness of individual methods was
assessed. Coordinated planning recommendations were developed on the basis of the
following findings.
4.1 Microclimatic comparative data of the extreme summer 2018
Mean annual air temperature (MAAT) values show that Heidelberg is among the warmest
areas of Germany, alternating with regions such as Lake Constance or Kai-serstuhl. Both
the number of summer days (maximum temperature 25 °C) and hot days (maximum
temperature 30 °C) are predicted to increase, representing an in-tensification of ex-
tremes. The urban heat island effect can be discerned in the central districts with a greater
frequency of hot days per year in the order of 24 days while in the surrounding forest
areas only three to four hot days are documented (average values related to the 30-year
reference period 1971-2000). In the long-term climate projection (RCP 8.5) for the period
2071-2100, the trend of global climate change becomes clearer (GEO-NET
Umweltconsulting GmbH & ÖKOPLANA, 2017; Intergovernmental Panel on Climate
Change, 2014). In the core city areas such as the Old Town, up to 41 hot days per year
are expected, while the average annual frequency of hot days in the nearby Odenwald
forest area will be around nine to twelve days. The agricultural areas to the west of the
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city also show up to 40 hot days per year during this period (GEO-NET Umweltconsulting
GmbH & ÖKOPLANA, 2017).
The summer of 2018 was marked by severe heat and drought in many parts of Europe,
North America and Asia (Rüegg, 2019; Vogel et al., 2019). Our two monitoring stations
installed at the two selected squares in Heidelberg recorded the highest average summer
temperature during June to August (JJA) of 22.7 °C in the Bahnstadt. The old town and a
comparison station of official state measuring stations in the city were each 0.2 K lower
(Fig. 3). In comparison, the two extreme summers 2015 and 2003 showed an average
temperature of 21.9 °C (2015) and 22.6 °C (2003) in Heidelberg between June and Au-
gust (Fig. 3) (Leutz, 2018).
The number of hot days for 2018 exceeded the average for 1981-2010 and reached the
range projected for the late 21st century (City of Heidelberg, 2015; GEO-NET
Umweltconsulting GmbH & ÖKOPLANA, 2017). In the historic city centre and the Bahn-
stadt, the number of hot days in 2018 was 44 and 46, respectively, higher than the 32 hot
days at the reference monitoring station outside the city centre. About half of the days in
the observation period June-August 2018 can therefore be classified as hot days. With
15 tropical nights, one more night with a minimum temperature of 20 °C was docu-
mented in the Bahnstadt than at the reference stations (Leutz, 2018).
The thermal isopleth diagram (Fig. 4) of the daily mean temperatures in 2018 compared
to the years since 2001, which were documented at an official state measuring station in
Heidelberg, shows the constantly high values of summer 2018. Daily mean temperatures
> 22 °C were attained almost continuously at all the stations as compared to previous
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years, where the daily mean temperatures in June, July and August frequently fell below
20 °C. In 2018, short temperature changes with daily averages below 20 °C only occur
on a few consecutive days, further illustrating the extremely consistent temperature con-
ditions with lower precipitation as compared to previous years.
Temperatures of different building materials and surfaces were measured during summer
of 2018. In the historic city centre a concrete bench under direct sunlight and the leaf
surface of a shrub in the sun were monitored during one day. The highest temperature
was reached by the concrete bench, starting at 34.5 °C and rising to a maximum of
47.2 °C in the afternoon. The average surface temperature was 42.6 °C. The tree leaf
surfaces heated up to 38.7 °C under direct sunlight (Leutz, 2018), representing a tem-
perature difference between a green element and a sealed design element of ~ -10 K,
despite prolonged dryness. The extreme heat and prolonged drought in summer 2018
(Åström, Bjelkmar, & Forsberg, 2019; Buras, Rammig, & Zang, 2019; Hartick, Furusho,
Goergen, & Kollet, 2019) also affected the vitality of the vegetation in Heidelberg, Ger-
many (Leutz, 2018). While vital green spaces on summer days 2017 showed values be-
tween 25-30 °C, the same but dried-up surfaces heated up to over 50 °C in 2018. Con-
sequently, the green areas show severe limitations in terms of their regulating effect under
prolonged drought and heat (Leutz, 2018).
4.2 Modelling of the solar potential
Given the high variability in urban solar radiation that arises from complex building struc-
tures and shadowing (Liang et al., 2014), a high resolution (sub-meter accuracy) solar
radiation simulation was undertaken. This analysis serves to model the effects of different
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22
degrees of greening and shading measures in public places on the average solar radia-
tion, taking into account the formation of shade (Liang et al., 2014). We computed the
solar potential in full 3D space for the period June to August 2018, i.e. how much solar
irradiation is theoretically received at a location over a given time period under clear-sky
conditions. Two scenarios were calculated, a current state based on a detailed 3D-build-
ing model without vegetation and a future scenario including fully developed vegetation
and artificial adaptation measures (Fig. 4). The scenarios’ differences in solar potential
provide a theoretical basis of the magnitude of reduction of direct solar irradiation as one
of the main drivers for local effects on thermal comfort.
The average solar potential at the Schwetzinger Terrace (white rectangle in Fig. 5),
summed up for the period June, July and August 2018, is 655 kWh/m², the adapted future
state is reduced to 274 kWh/m² (Fig. 5). At University Square, the average amounts to
450 kWh/m², the mean value of the solar potential for the adapted future state is 228
kWh/m² (Leutz, 2018).
As shown here, adjustments that enhance shading and minimize irradiation and heating
can reduce the solar potential of selected areas by more than 50 % (Schwetzinger Ter-
race) (Fig. 5). As described above, the current tree population of the squares was not
taken into account for the current state, due to a lack of data. This leads to an overesti-
mate of the effect of shading measures at University Square, where some trees are cur-
rently present. However, the large potential reduction calculated for the Schwetzinger
Terrace can be considered as a good approximation, because there the tree population
as of 2018 has made little progress in its development with very little shadow casting
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effect that can therefore be neglected for the current state (Fig. 5) (Leutz, 2018). Reduc-
tion of heat generation due to shaded areas increases the quality of life in public places
during the hot summer season (Lafortezza et al., 2009). Thus the spatial model aims to
emphasise the effect of solar radiation shading measures and quantifies the added value
of the adaptation measures (Leutz, 2018; Liang et al., 2014).
4.3 Approaches from social sciences
Beyond physical adaptation to the climatic conditions, social aspects play an important
role in the design of public spaces (Menny, Palgan, & McCormick, 2018). In urban areas,
in contrast to rural areas, every built element has an assigned function. Open spaces,
principally squares and parks, have a unique selling point in the built-up city in this respect
and do not follow this pattern. In public space one encounters a diversified simultaneity
of cultures, uses, generations, active and passive being. They are dynamic, both in the
course of the seasons and in the interaction with the users, and are mirrors of change in
the more static, sealed space of the city (Castan Broto & Bulkeley, 2013; Lafortezza et
al., 2009; Nikolopoulou & Lykoudis, 2006; Petrow, 2011).
The questionnaire survey showed a clear perception of more extreme temperatures and
weather events, as well as a positive opinion regarding the squares. In most cases, how-
ever, these squares are not used for recreational purposes. The majority of the respond-
ents cited their inadequate design as the reason for this. An increase in the proportion of
green areas and the integration of natural elements were represent the most important
factors increasing the quality of stay (Leutz, 2018) (Fig. B1 in Supp. Mat.)
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The mental maps highlight possible improvements for public spaces. In general, the par-
ticipants assessed the design and usability of public spaces more critically than respond-
ents to the questionnaire survey. Citizens identified the lack of shading, the low proportion
of green spaces and the social structure of the users of public spaces as the most nega-
tive aspects. In addition to these factors, the problematic traffic situation and heat stress
during the summer months also play a central role at the University Square (Fig. 6). The
traffic situation was described by one respondent as life threatening. In addition, partici-
pants responded negatively (“absurd” and “ugly”) to the architecture of the surrounding
buildings and their facades (Leutz, 2018). The homogeneity of the Schwetzinger Terrace,
both visually and socially, was also criticised. The "grey" architecture of the Schwetzinger
Terrace and the surrounding buildings were often criticized. Participants instead called
for "other materials, more green, [and] natural buildings" (Leutz, 2018).
In many cases specific and practical suggestions with regard to more diversity, greening
and shading in public places in Heidelberg were expressed (Leutz, 2018). Nature and
vegetation bear positively on well-being, reduce stress and facilitate recovery (Fig. 6).
Free spaces are therefore important for biodiversity, health promoting life conditions and
the competitiveness of cities and regions (Lafortezza et al., 2009; Nikolopoulou &
Lykoudis, 2006; Schuster et al., 2017).
4.4 Evaluation of the effectiveness of the methods used
The case study has shown differences in the effectiveness of the various methods de-
pending on the objective. In general, the first part of the study focussed on quantitative
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methods, which can only represent partial aspects of reality. The collection of meteoro-
logical and climatic data is necessary to assess the need for adaptation and to make
places comparable. However, its application was limited in time and space compared to
the variability in temperatures from climate change. Modelling the effects of shading
measures on the microclimate of public spaces can be used for various purposes and
serves to evaluate the reduction of the direct solar irradiance through adaptation
measures. The effectiveness of solar modelling relates mainly to the properties of the
underlying data, with the accuracy and validity of our results limited by the fact that the
official 3D city models do not contain any information about vegetation objects. In addi-
tion, the results only show the reduction of solar potential, but they cannot be interpreted
as a measure for quality of life. However, the data could be used as valuable input in
models for thermal comfort or biometeorology (Ketterer & Matzarakis, 2014; Matzarakis
& Endler, 2010).
Methods from the social sciences allow insights into how citizens and users of the squares
perceive the climate and how this affects their well-being. Mental maps provide even
deeper personal insights into the perception of places and the users' desire for a more
pleasant design and adaptation to the increasing generation of heat. The questionnaire
survey is a standardised test procedure whose results can be subject to many factors
(e.g. social desirability, interview situation, motivation of participants, number of cases
and objectivity). The method allows general conclusions to be drawn only in the case of
a high number of interviews. Furthermore, no causes of the current conditions and opin-
ions are included. Mental maps represent two-dimensional, subjective images. They are
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26
essential in order to obtain suggestions for concrete measures from the users of the lo-
cations, which are based on people's desire for quality of stay and attractive design. In
addition, the involvement of citizens can create bond and acceptance for places and ad-
aptation measures. However, these maps and images are simplified, showing only ex-
cerpts. Nevertheless, the multi-perspective approach is emphasized by balancing the lim-
itations of the individual methods. Finally, the active involvement of non-scientific actors
and perspectives can strengthen mutual trust in the cooperation and thus create ac-
ceptance and increase feasibility (Adler et al., 2018; European Environment Agency,
2016; Hirsch Hadorn & Pohl, 2007; Lemos et al., 2018; Strohschneider, 2014).
4.5 Co-design of coordinated planning recommendations
Whether a public area is actually accepted and how the quality of stay is evaluated can
be determined by observation and questioning. A particular focus is on the quality of open
spaces in the summer months, when the bioclimatic recreational function makes an im-
portant contribution to health protection. In the context of climate change adaptation, rec-
ords of the summer quality of stay in a public square form the basis of a combination of
objective, scientifically ascertained and subjective criteria. These social science methods,
providing valuable information and recommendations for sustainable open space plan-
ning and forms the basis for standardisation and evaluation of design elements adapted
to climate change. The data provide important arguments for a climate change-adapted
open space design and can help to ensure that this aspect is better accounted for in the
planning process. In this way, the needs of future users can be better assessed in ad-
vance, especially for new open spaces to be planned, and planning conflicts, which could
lead to a rejection of planning, may be avoided.
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Based on the individual results, a co-benefit of the wishes and ideas of the respondents
with the climate-regulating effect of design elements can be generated. Multifunctionality
and diversity in terms of design (colour, elements, greenery, etc.) and use (working, re-
laxing, viewing, playing, communicating, consuming, etc.) are the most important aspects.
Adjustments such as creating seating in shaded areas, unsealing, separating traffic and
recreation areas, and integrating temporary solutions all take equally account of both ob-
jectives. Shady trees in particular can have a positive effect on the temperature and mi-
croclimate of open spaces with sparse vegetation and reduce heat stress (Lindberg,
Thorsson, Rayner, & Lau, 2016). In addition, green areas generally have a positive effect
on the mental health of city dwellers (Tost et al., 2019). Furthermore, identity-creating
measures play a role (Lafortezza et al., 2009; Leutz, 2018; Nikolopoulou & Lykoudis,
2006). Based on the data collected, no conflicts of use are to be expected during imple-
mentation.
Our approach could be further enhanced, e.g. by various methods of observation and
quantification that can provide further insight into the interactions between public life and
space. These include techniques of counting, recording, locating, photographing, tracing,
geotracking, routing, mapping and some other methods like documentation of dwell times
under the key questions Who? When? Where? and What?. Detailed and comparative
studies on urban life can be the starting point for improving urban quality of life. Moreover,
in some cases, adaptation to future developments can be based on traditional knowledge.
The positioning, choice of materials or orientation of buildings or urban structures to nat-
ural occurrences are well known, but are gaining importance again in the trend towards
climate change and adaptation.
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5. Conclusion
The pilot study demonstrates how transdisciplinary research can be structured and de-
scribes a holistic approach that is supported by local stakeholders. The diversity of per-
spectives creates an empirical basis for what is desirable in sustainable urban planning
and the adaptation of public spaces to climate change. Furthermore, the measurement of
climatic conditions provides arguments for additional measuring stations to capture com-
plementary parameters and to achieve a higher temporal and spatial resolution. The 3D
solar analysis is also transferable to other locations and makes adaptation measures
quantifiable.
The involvement of the public (citizen science) formed an essential component of this
work. The transdisciplinary approach also makes the study more significant and mean-
ingful with regard to multidimensional adaptation strategies of urban open spaces to cli-
mate change. The involvement of stakeholders and citizens was viewed positively by all
project partners in terms of the results and the generated added value. The data on the
perception of climate change and the ideas about the design of public spaces reflect
grievances and perceived problems.
The combination of physical measurements, solar modelling, and surveys of public per-
ceptions represent an integrated set of methods whose results give rise to adaptations
and improvements. Taking into account the perspective of the relevant stakeholders and
users in the sectoral planning, the overall data set serves to develop practical solutions
for improved designs of open spaces in the city of Heidelberg under the aspect of climate
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change adaptation and methodological enhancements in basic research (Fig. 1, 5) (Leutz,
2018).
Author contributions
K.F. conducted the measurements and surveys and analysed the data. The concept of
the study was mainly co-designed by K.F., N.A. and R.W. The focus of B.H.'s contribution
was to provide enriching impulses through solar potential analysis. W.A. and N.A. pro-
vided guidance and support for the different parts of the project. A.S. contributed expertise
in the area of physical geography and provided the necessary technical measuring equip-
ment. R.W. supported the project as a stakeholder with local practical knowledge. All
authors worked on the manuscript.
Competing interests
The authors declare no competing interests.
Declaration of interests
The authors declare that they have no known competing financial interests or personal relationships
that could have appeared to influence the work reported in this paper.
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Additional information
Correspondence should be addressed to K.F.
Acknowledgements
We thank Vivien Zahs for support in the application of solar modelling. Sincere thanks are
given to the City of Heidelberg, especially Hubert Zimmerer, Sabine Lachenicht, Chris-
toph Czolbe, and colleagues for supporting different parts of the project. We thank Timo
Mifka from Heidelberg University as well as Martin Geißler and Tim Szpalecki from the
City of Heidelberg for providing access to the measuring areas, Helmut Scheu-Hachtel
and Zarko Peranic from the LUBW for support in data provisioning. Further we would like
to thank Viktoria Reith and the staff of the Department of Geography of Heidelberg Uni-
versity of Education for their support in the measurements, equipment provision and sur-
veys. Many thanks are given to Jack G. Williams for advice on the initial draft and proof-
reading of the manuscript. We gratefully acknowledge fruitful discussions and inspiration
provided by Michael Stauffacher (USYS TdLab ETH Zurich). This work was partly funded
by the Federal Ministry of Education and Research (BMBF) of Germany in the framework
of the project ER3DS (FKZ: 01DO19001). Funding for the project (position of K.F.) was
provided by the Heidelberg School of Education (Heidelberg University and University of
Education Heidelberg, Germany).
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Fig. 1 │ Transdisciplinary concept of methods to co-design adaptation measures.
The transdisciplinary aspect of this case study is achieved by drawing on the expertise of
public institutions such as the Office of Environmental Protection, Trade Supervision and
Energy Heidelberg, Germany (Heidelberg Environmental Office) and the Heidelberg City
Planning Office, by involving citizens through surveys, and by communicating scientific
results to the public.
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Fig. 2 Location of the city of Heidelberg, Germany. In addition, the positions and
aerial photographs of the two public squares of the city considered in the pilot study are
displayed (© OpenStreetMap contributors 2019).
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Fig. 3 Summer air temperatures in Heidelberg since 2001. Mean values of the air
temperature for the period June to August (squares), with the standard deviation of the
respective distribution of daily mean temperatures (shading). For 2001 to 2018, values
from one official weather station were averaged, for 2018 data of the stations installed for
this study are shown in addition (lighter red points).
Fig. 4 │ Thermal isopleth diagram of the daily mean temperatures at three measur-
ing stations in Heidelberg, Germany. The upper three lines represent the 3 curves for
2018 at the three measuring stations Bahnstadt (b), old town (c) and the official state (a)
measuring station of Heidelberg. In addition, the measurements of the previous years at
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the official state measuring station are shown for comparison (a). The measurements
were taken in the summer months June, July and August. Compared to the previous
years, the year 2018 appears extremely warm and hot.
Fig. 5 Actual and possible future situation and solar potential for Schwetzinger
Terrace. Modelling of solar potential at the ground surface and heating of surfaces was
performed using the tool VOSTOK (GIScience Heidelberg University, 2016). Values are
solar potential summed up over the entire summer (June through August 2018) for
Schwetzinger Terrace in the sustainable district Bahnstadt, Heidelberg. A Modelled solar
potential for the current state, B Aerial photograph of the Schwetzinger Terrace, summer
2018, showing the barely existing shade, C Visualization of the adapted future state with
fully developed vegetation and artificial shading measures, D Modelled solar potential for
the assumed adapted future state.
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Fig. 6 Two different results from the mental maps survey in Heidelberg, Germany
in summer 2018. On the left a representation of the university square in the old town of
Heidelberg. The square is presented rather negatively, with a danger symbol concerning
the traffic. Green elements like trees are not shown. Furthermore, the use of the square
for demonstrations is discussed. On the right side a positive example of a public square
in Heidelberg is shown. The market place in the district of Neuenheim is used as a meet-
ing place and for staying. Cafés and shops are located there, which are positively per-
ceived. In addition, the large trees on the square are characteristic positive features.
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... Heidelberg is situated at the banks of the river Neckar at the exit of the Neckar river valley into the Upper Rhine Graben (Foshag et al. 2020). The annual average temperature is 11.4°C, the hottest month is July with an average temperature of 20.6°C and the coldest is January with an average temperature of 2.4°C. ...
... Besides the already mentioned limitations in the course of this work, a further limitation in the context of the ER3DS project is that the use of highly detailed 3D spatial sensing and analysis was not incorporated. Further research, that could incorporate highly detailed 3D spatial sensing and analysis could be a solar potential analysis as conducted in the papers of Foshag et al. 2020 andLin et al. 2017 associated with ER3DS project. The study of Foshag et al. 2020 used the solar potential analysis to quantify the reduction of solar irradiance by installing different design elements on the study sites. ...
... Further research, that could incorporate highly detailed 3D spatial sensing and analysis could be a solar potential analysis as conducted in the papers of Foshag et al. 2020 andLin et al. 2017 associated with ER3DS project. The study of Foshag et al. 2020 used the solar potential analysis to quantify the reduction of solar irradiance by installing different design elements on the study sites. In the paper of Lin et al. 2017, they used the solar potential analysis to calculate the solar potential of building roofs to quantify the carbon-reduction potential of rooftops with solar panels and proposed a reduction strategy for reducing CO2 emissions from urban activities. ...
Thesis
Heat, especially in urban areas, is becoming a more and more serious problem because of global warming and urban heat island effects. Due to urban warming and heat in cities negative consequences evolve, such as higher energy consumption and more heat-related illnesses. Especially during summer high temperatures can lead to reduced thermal comfort in urban areas. This endangers the future usability of public spaces in cities. In the context of the ER3DS project, a joint research project between Heidelberg and Tainan academics to integrate knowledge regarding highly detailed 3D spatial sensing and analysis, building energy use, and urban climate, this work took place. This study aims to further contribute to the ER3DS project with the assessment of the microclimatic conditions to determine thermal comfort at the Marktplatz in Heidelberg and the Blueprint Park of Tainan; the identification of already existing heat reducing measures at those spaces; and the estimation which heat-reducing measures should be further implemented and to what extent, in order to ensure future thermal comfort. The method chosen to calculate thermal comfort is the thermal index physiological equivalent temperature (PET), which requires meteorological measurements of air temperature, relative humidity, wind speed and mean radiant temperature. Thermal comfort was additional evaluated by using a questionnaire survey. The questionnaires also surveyed the opinions and suggestions of people using the public spaces regarding measures for microclimatic improvement. It was found that thermal comfort in both places was reduced during summer due to heat stress. The questionnaire survey indicated, that thermal adaptations of the people using outdoor spaces play also important roles in the adaptation to outdoor thermal conditions. Furthermore, heat reducing measures preferred by the users of the Marktplatz and the Blueprint Park could be evaluated. Plants had been foremost suggested in Heidelberg and plant, shade, better access to water and airconditioning had been proposed in Tainan. The further implementation of heat adaptation measures at the two study sites not only seems necessary to ensure future usability in a warming world, but can also mitigate urban warming by contributing to e. g. building energy reduction.
... The current crises, which are impacting contemporary society and which, in the coming decades, will turn into important global challenges, make it urgent to deeply consider what characteristics cities and territories must adopt [1,2]. Undoubtedly, the city, the place of maximum expression of human phenomena [3], need be placed at the center of a discussion that concerns different scientific and humanistic disciplines [4][5][6][7][8][9]. Cities must again be the place that allows human flourishing and the enhancement of the communitarian environment [10]. ...
Article
Full-text available
Current changes are making communities, cities, and territories increasingly vulnerable. Urban architectural interventions have the power to intervene this situation, directly reducing vulnerabilities or backing social initiatives. Urban and architectural interventions, however, are also those that take a longer time to be implemented and to impact society. For this, these interventions must be sustained by broad and transversal visions, as well as referring to the temporal context of the coming decades. For these reasons, the research project “Design for Vulnerables” aims to define which methodologies should be adopted to reduce urban vulnerabilities in the coming decades. A design workshop, set in a vulnerable community in the northern Mexico, was organized, documented, and analyzed. Based on the research by design methodology, the research highlighted current issues, transversal to urban-architectural design, which influence urban vulnerabilities. This multidisciplinary approach made it possible to generating a set of principles of Design for Vulnerables, graphically represented by a re-interpretation of the Krebs cycle.
... A pilot study from Heidelberg, Germany, on a new sustainable urban quarter that experienced more pronounced heat stress than the historic city center (in the hot and dry summer of 2018) demonstrated the usefulness of an interdisciplinary approach to identify appropriate heat adaptation measures. The method presented, which is also based on a questionnaire survey of the perception of public spaces, showed how important it is to design them properly, facing not only climate change, but, above all, social expectations [16]. Similar results were obtained by Italian researchers, also indicating a lower tolerance of local environmental conditions by residents compared to tourists [17]. ...
Article
Full-text available
Noticeable climate change in recent years is reducing the comfort of public spaces in the urban environment, and is becoming an element of urban policies. The adaptation to climate change requires the development of new design guidelines for the development of public spaces. The appropriate definition of development density, choice of building materials, technologies, planting species, and the used directions is a challenge that depends on local conditions. A representative public space located in the area of a multi-family housing estate built in the second half of the 20th century in Lublin (Poland) was selected for the study. The space has undergone redevelopment twice in the last 10 years. The aim of the study was to determine to what extent the executed and designed changes actually improve the thermal comfort of users. Quantitative and qualitative indicators of the successive phases of the investment were analyzed in the context of projected climate change. The simulation was developed using the ENVI-met version 5.0 software. As a result of the changes made, there has been an improvement in usability and comfort. Five simulations were carried out for the warmest day of the year for one of the public spaces in the city of Lublin. The sensation of PET thermal comfort was investigated for people aged 35 and 75, as a particularly sensitive group. The obtained result proved that the elderly feel higher temperature rates than younger people. In one of the simulations, new plantings were proposed to improve the local microclimate. The material temperatures of paved surfaces were also investigated. The article shows how the local microclimate and people’s desire to stay in a given space can be improved with new tree planting.
... Vegetation, particularly trees, are an important factor to the local climate (i.e. microclimate) within cities, for example by contributing to air quality or thermal comfort of people in public spaces (Foshag et al., 2020). Urban trees are subject to increasing heat stress during hot summers, which may impede their positive effects on the urban climate andworst caselead to dying of trees. ...
Technical Report
Full-text available
Urban regions are particularly affected by increasing heat waves due to climate change. Vegetation, particularly trees, are an important factor to the local climate (i.e. microclimate) within cities. However, urban trees are subject to increasing heat stress during hot summers, which may impede their positive effects on the urban climate and – worst case – lead to dying of trees. With increasing requirements to curate trees and limited resources (e.g., water, human power) there is increasing relevance to develop new strategies, for example, using digital geotechnologies for urban tree management. Cities in geographic regions with overall hotter climate (than in central Europe) are already more adapted to conditions of strong heat than German or central-European cities. This study gathers insights about strategies of urban tree management in Taiwan. This entails a survey of literature and publicly available resources, and direct interviews. Interviews are conducted with two scientific partners from Taiwan. In the frame of this survey, it was not possible to conduct interviews with stakeholders (formal requests were made to several city governments). According to public resources and the information gained with the interviews, urban trees in Taiwan play an important role for different aspects: they have a function for aesthetics and culture, but also for thermal comfort and provision of shade during periods of high temperatures. There is increasing awareness of the importance of trees in the population in the environmental context. Linked to this, an increasing number of actions to avoid the removal of trees, for example, for construction can be observed. The management of urban vegetation is handled by different departments in the cities. Generally, the maintenance of urban trees, particularly trimming and irrigation, are outsourced to contractors. Irrigation mainly relies on watering trucks and human power, and may be limited in dry periods when there is low availability of water. Mostly fresh water is currently being used, some cities already changed to using gray water for irrigation. So far, in Taiwanese cities the deployment of geotechnology in urban vegetation management regards mapping of trees for cadasters, with additional in-situ measured structural parameters. In current research projects in cooperation with city planning, meteorological data is recorded for monitoring the urban microclimate. These existent monitoring setups could be integrated for an improved understanding on the status of urban trees, by linking to new observation parameters, such as soil humidity at the position of individual trees or spatial information on the vitality of trees via (airborne) image acquisition. Similar to the current standard approach of urban tree management in Germany, there seems to be large potential for adopting new strategies of monitoring and managing trees. The situation in Taiwan shows various similarities to current strategies of tree management, mainly irrigation, in German cities. For example, in most cases watering trucks and expert-based scheduling of irrigation at street level are used. Therein, the capacity of irrigation during dry periods is limited by the availability of water and the capacity of human power. Both countries may hence greatly benefit from investigating new strategies of integrating digital geotechnologies to monitor urban vegetation for more targeted requirements of water and further maintenance.
... Foshag, K., Aeschbach, N., Höfle, B., Winkler, R., Siegmund, A. & Aeschbach, W. (2020): Viability of public spaces in cities under increasing heat: A transdisciplinary approach. Sustainable Cities and Society, 59, 102215. ...
Technical Report
Full-text available
Das Ziel dieses Projekts war die Integration von Wissen taiwanesischer und deutscher Wissenschaftler*innen in den Bereichen hochdetaillierte 3D-Raumerfassung und -analyse, Energieinitiativen und Veranstaltungen. Die ursprüngliche Umsetzung war in mehreren gemeinsamen Workshops und Feldexperimenten geplant, ebenso wie Software-Trainingsprogramme. Dies ermöglicht die Förderung des wissenschaftlichen Nachwuchses (Master- und PhD-Studierende) auf hohem wissenschaftlichem Niveau. Der urbane Kontext in Taiwan stellt zudem eine neue wissenschaftliche Herausforderung für existierende Methoden der 3D-Solarpotenzialberechnung dar und soll helfen, die Robustheit und Übertragbarkeit dieser Methoden zu erweitern. Intensiver Wissensaustausch zwischen den Projektpartner*innen ermöglicht somit die Entwicklung neuer Konzepte für die Extraktion von Geoinformation. Über gemeinsame i) Forschung als auch ii) Lehraktivitäten hinaus wurden öffentliche Behörden und KMUs als Akteur*innen in Workshops und Ausbildungsaktivitäten eingebunden, um wissenschaftliche Ergebnisse und entwickelte Werkzeuge Endnutzer*innen in Smart Cities nahe zu bringen. Da geplante Projektaktivitäten aufgrund der Pandemielage teilweise nicht umgesetzt werden konnten, wurden die Projektziele in zwei Aspekten ausgebaut: (1) Die Berücksichtigung des thermischen Komforts im Kontext des städtischen Mikroklimas, um die Nutzbarkeit öffentlicher Plätze angesichts einer Zunahme von Hitzestress vor allem in Stadtgebieten zu evaluieren. (2) Die Untersuchung des städtischen Vegetationsmanagements zur Erarbeitung neuer mögliche Strategien, um die Vitalität insbesondere von Bäumen durch gezielte Bewässerung zu erhalten. Der Auftaktworkshop im März 2019 ermöglichte es, Wissen aus der Geographie, Geoinformatik, Geodäsie, Architektur, Planung und Umwelt, Gebäudeenergie und von Stadtklimaexpert*innen aus Taiwan und Deutschland für zukünftige Forschungsaktivitäten und Anwendungen zu integrieren. Die ausgewählten Referent*innen und Teilnehmenden aus dem akademischen Bereich, KMUs und Behörden wurden zusammengebracht, um die (zukünftige) Rolle von 3D-Geodaten und 3D-Analysen für die Emissionsreduzierung im Smart-City-Kontext (z.B. intelligente gebäudeintegrierte Photovoltaik) zu bewerten. Als Ergebnis des transdisziplinären Workshops wurde Erfahrung aus verschiedenen Richtungen ausgetauscht und bestehende und neue (gemeinsame) Anwendungsbeispiele identifiziert. Darüber hinaus wurden neue Projektpartner*innen in Heidelberg und Taiwan zusammengebracht und somit die Grundlage geschaffen, die wichtigsten Herausforderungen zwischen Wissenschaft und Praxis sowie zwischen Deutschland und Taiwan anzugehen. Im Rahmen des zweiten Projekt-Workshops, der im September 2019 in Taiwan stattfand, präsentierten die Projektkoordinatoren und Nachwuchswissenschaftler*innen ihre Forschung zum ER3DS-Thema mit besonderem Fokus auf die Situation in Taiwan. Während des Aufenthalts in Taiwan fanden zudem Treffen mit verschiedenen Akteur*innen statt, mit besonderem Fokus auf dem Projektthema des Einsatzes erneuerbarer Energien im Kontext von Smart Cities. Wichtige Vernetzungen und Wissensaustausch konnten vor allem in Treffen mit den Stadtverwaltungen der Millionenstädte Taichung und Kaohsiung erzielt werden. In diesem Rahmen fanden zudem Begehungen verschiedener Beispiele von Gebäudeinfrastruktur mit integrierter Begrünung statt, die im Rahmen des KAOHAUS Programms umgesetzt werden. Diese Konzepte, beispielsweise begrünter Balkone in Apartment-Hochhäusern oder integrierter Photovoltaikanlagen, tragen maßgeblich zu einer positiven Beeinflussung des Stadtklimas bei und sollen helfen, die jeweiligen Gebäude vor Erhitzung zu schützen. Bei den weiteren Projektaktivitäten zum Thema des städtischen Mikroklimas und thermischen Komforts handelt es sich um eine vergleichende Studie zwischen Taiwan und Deutschland. Hier wurde ein Index zur Berechnung des thermischen Komforts in verschiedenen Klimabedingungen verwendet. Dazu wurden meteorologische Variablen im Rahmen der Feldforschung in Tainan (Taiwan) und Heidelberg (Deutschland) an jeweils einem öffentlichen Platz aufgenommen. Ergänzend wurde der thermische Komfort von Personen auf den Plätzen über einen Fragebogen erfasst, sowie individuelle Meinungen und Verbesserungsvorschläge zum Mikroklima erfragt. Die Messungen zeigen, dass beide Plätze als thermisch nicht komfortable Orte gelten. Als Maßnahmen zur Reduzierung der Hitzebeeinträchtigung wurden überwiegend Pflanzen, aber auch weitere Schattenplätze, besserer Zugang zu Trinkwasser und Klimaanlagen genannt. Um zu untersuchen, wie Maßnahmen der Beschattung, beispielsweise durch Bäume, das Mikroklima positiv beeinflussen können, wurde die Sonneneinstrahlung für einen Heidelberger Platz im Detail untersucht. Diese wurde auf Basis von 3D-Stadtmodellen in Forschungssoftware zur Solarpotenzialberechnung abgeleitet. Für die Untersuchung eines potentiellen zukünftigen Zustands wurden der gleichen 3D-Szene ausgewachsene Bäume und künstliche Beschattungsmaßnahmen virtuell hinzugefügt. So ergibt sich, dass die hohe Hitzebeeinträchtigung im Ist-Zustand durch Anpassungsmaßnahmen, wie zum Beispiel Baumbepflanzung, an dem untersuchten Platz maßgeblich reduziert werden kann. Für den mindernden Effekt durch Baumvegetation ist jedoch entscheidend, dass diese vital ist, was unter den aktuellen Entwicklungen mit zunehmenden Dürreperioden und Hitzestress eine zusätzliche Herausforderung darstellt. Im Hinblick auf die erforderliche Entwicklung neuer Strategien des Vegetationsmanagements, insbesondere zur Bewässerung von Bäumen zum Erhalt der Vitalität, wurde im letzten Projektabschnitt eine Studie zum aktuellen Vegetationsmanagement und potenziell geplanten Anpassungen in deutschen und taiwanesischen Städten durchgeführt. Dieser Thematik wurde in Austauschtreffen mit zwei deutschen Städten eine hohe Relevanz zugesprochen. Für die zukünftige Erarbeitung angepasster Strategien wird ein wesentlicher Faktor sein, dass sich Methoden bewähren und somit für die Städte langfristig umsetzbar sind. Die Untersuchung der Situation in Taiwan wurde durch Recherche von Literatur und öffentlichen Ressourcen und durch Interviews mit wissenschaftlichen Partner*innen in Taiwan durchgeführt, sowie durch Kommunikation durch die taiwanesischen Projektpartner*innen mit verantwortlichen Personen der Stadtverwaltungen mehrerer großer Städte. Die Nutzung digitaler Geotechnologien betrifft derzeit, ähnlich der Herangehensweise in deutschen Städten, die Erfassung des Baumzustands in einem Baumkataster der jeweiligen Stadt. Diese werden typischerweise durch in-situ Messung der Koordinaten und weiterer Parameter, wie zum Beispiel Baumhöhe und Durchmesser auf Brusthöhe, erfasst. Diese Aufgabe ließe sich zukünftig durch die Aufnahme und Auswertung von 3D-Geodaten weitgehend automatisieren und auf sehr große Gebiete skalieren, unter Minimierung von Personaleinsatz. Aus dem gewonnenen Wissen und Austausch mit Akteur*innen der verschiedenen Städte lässt sich zusammenfassen, dass der operationelle Einsatz von digitalen Geotechnologien zur Beobachtung des Baumzustands das gezielte Baummanagement in Städten maßgeblich unterstützen kann. Ein solcher Ansatz könnte einen wesentlichen Beitrag zu Anpassungsstrategien an den fortschreitenden Klimawandel und dessen Einflüsse auf das städtische Klima leisten und wird in weiteren Forschungsaktivitäten verfolgt. Eine wichtige Komponente wird hierbei weiterhin der enge Austausch und Integration von Wissen von Anwender*innen und Nutzer*innen (KMUs und Behörden) sein, welche nur durch die Berücksichtigung transdisziplinärer Herangehensweisen (insb. durch Zusammenarbeit mit dem TdLab Geographie, Universität Heidelberg) erreicht werden können. Die Umsetzung des Projekts und Erarbeitung der Inhalte zu verschiedenen Thematiken war nur durch die erfolgreiche Kooperation und Austausch zwischen den deutschen und taiwanesischen Forschungsgruppen der Universität Heidelberg und National Cheng Kung University möglich. Die Vernetzungsaktivitäten stellen einen wichtigen Ausgangspunkt für die Ausarbeitung anknüpfender Forschungsprojekte und Entwicklungsaktivitäten dar.
... Vegetation, particularly trees, are an important factor to the local climate (i.e. microclimate) within cities, for example by contributing to air quality or thermal comfort of people in public spaces (Foshag et al., 2020). Urban trees are subject to increasing heat stress during hot summers, which may impede their positive effects on the urban climate andworst caselead to dying of trees. ...
Article
Full-text available
Urban regions are particularly affected by increasing heat waves due to climate change. Vegetation, particularly trees, are an important factor to the local climate (i.e. microclimate) within cities. However, urban trees are subject to increasing heat stress during hot summers, which may impede their positive effects on the urban climate and – worst case – lead to dying of trees. With increasing requirements to curate trees and limited resources (e.g., water, human power) there is increasing relevance to develop new strategies, for example, using digital geotechnologies for urban tree management. Cities in geographic regions with overall hotter climate (than in central Europe) are already more adapted to conditions of strong heat than German or central-European cities. This study gathers insights about strategies of urban tree management in Taiwan. This entails a survey of literature and publicly available resources, and direct interviews. Interviews are conducted with two scientific partners from Taiwan. In the frame of this survey, it was not possible to conduct interviews with stakeholders (formal requests were made to several city governments). According to public resources and the information gained with the interviews, urban trees in Taiwan play an important role for different aspects: they have a function for aesthetics and culture, but also for thermal comfort and provision of shade during periods of high temperatures. There is increasing awareness of the importance of trees in the population in the environmental context. Linked to this, an increasing number of actions to avoid the removal of trees, for example, for construction can be observed. The management of urban vegetation is handled by different departments in the cities. Generally, the maintenance of urban trees, particularly trimming and irrigation, are outsourced to contractors. Irrigation mainly relies on watering trucks and human power, and may be limited in dry periods when there is low availability of water. Mostly fresh water is currently being used, some cities already changed to using gray water for irrigation. So far, in Taiwanese cities the deployment of geotechnology in urban vegetation management regards mapping of trees for cadasters, with additional in-situ measured structural parameters. In current research projects in cooperation with city planning, meteorological data is recorded for monitoring the urban microclimate. These existent monitoring setups could be integrated for an improved understanding on the status of urban trees, by linking to new observation parameters, such as soil humidity at the position of individual trees or spatial information on the vitality of trees via (airborne) image acquisition. Similar to the current standard approach of urban tree management in Germany, there seems to be large potential for adopting new strategies of monitoring and managing trees. The situation in Taiwan shows various similarities to current strategies of tree management, mainly irrigation, in German cities. For example, in most cases watering trucks and expert-based scheduling of irrigation at street level are used. Therein, the capacity of irrigation during dry periods is limited by the availability of water and the capacity of human power. Both countries may hence greatly benefit from investigating new strategies of integrating digital geotechnologies to monitor urban vegetation for more targeted requirements of water and further maintenance.
... However, this growing availability of data, and their integration in urban analysis, still leaves a gap between knowledge and action [9,39], as it misses a further integration step in terms of decision-making workflows. From one side, the need for public space to have sustainable development strategies, and to be able to resist and react to environmental urban transformations, moves the local PA (Public Administration) to look for adequate design solutions; from the other side, the proposed SIs hardly match with the procedures of decision-makers [40]. ...
Article
Full-text available
The design of urban public open spaces plays a key role in the development of micro-scale reactions to global phenomena (pandemic, climate change, etc.) that are currently reshaping the human habitat. Their transformability and healthy influence on the urban environment make them strategic nodes for acupunctural regeneration with systemic effects. Several methods, models, and indicators have been developed to face the complexity of these spaces, made up of tangible and intangible layers; however, there is a gap between theoretical investigation and the need for public administrations to devise feasible solutions, strategies, and guidelines. The paper focuses on this mediation, presenting, as a case study, an adopted methodology and the first results achieved according to guidelines for the regeneration of the system of squares in the historical center of Alessandria (Piedmont, Italy). In this case, a multidisciplinary approach and a Multi-Criteria Analysis (MCA) method, supported by geospatial analysis and GIS technology, have been employed to work as mediators for a participatory process which will involve public administration, stakeholders, experts, and researchers. The paper presents an overview of the workflow, with a focus on the first set of thematic indicators and an open conclusion. It will explain how they have been defined, integrated, and turned into a dialogic tool, with the aim of laying the foundation for the next stage of involvement by the public administration and stakeholders. Specific attention will be paid to the key role of vegetational and environmental parameters, which represents the requalification strategy’s backbone, for both local and systemic scales.
... Moreover, adaptation solutions to climate change must be developed on the basis of inter-and trans-disciplinary cooperation. For example, adapting public spaces to climate change requires the simultaneous contribution of climatic, ecological, design, sociological and economic aspects (Foshag et al. 2020). The objectives of the paper are twofold. ...
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... In the case of a pilot case in Heidelberg, Germany, increasing tree canopy cover to enhance shading and reduce solar irradiation and thus mitigate heat stress was found to generate synergy effects by improving both climatic and social conditions (Foshag et al., 2020). The study combined measurements of air temperatures, modelling of climate impacts with detailed spatial modelling of solar radiation shading measures, and the involvement of relevant stakeholders. ...
Technical Report
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BOOK is NOT available for DOWNLOAD. Fourth edition available from https://www.routledge.com/Doing-Survey-Research-A-Guide-to-Quantitative-Methods-4th-Edition/Nardi/p/book/9781138043398 Intended for people who want to learn how to conduct quantitative studies for a project in an undergraduate course, a graduate-level thesis, or a survey that an employer may want completed. This brief, practical textbook prepares beginners to conduct their own survey research and write up the results, as well as read and interpret other people's research. It combines survey design with data analysis and interpretation. And it is for those who need to understand and critically interpret survey research found in scholarly journals, reports distributed in the workplace, and social scientific findings presented online in the media, on a blog, or in social media postings.
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Thesis
"An old city like Heidelberg illustrates how its public space survives the renewal phases of its buildings and makes places permanently distinguishable. It is above all the built public space of a city that carries sustainability and identity in its structure – a goal to which Heidelberg feels particularly committed.” (STADT HEIDELBERG 2005). The great challenge of climate change requires solutions, especially in cities, which are equally responsible for a large part of the anthropogenic greenhouse effect. Current questions on climate change adaptation have a high practical relevance for sustainable urban development on the one hand and for current scientific aspects on the other. Sustainable future models of the modern city primarily aim at reduction, with two essential factors: energy saving and energy efficiency. Increasing heavy precipitation and overheating events are examples that affect all fields of action of the city and require adaptation strategies. The main objective of this project is to collect data, evaluate various climate parameters and to survey citizens on their perception of climate change and the design of public spaces in Heidelberg. The comparison of locations in the historical old town with newly created areas makes it possible to evaluate the key factors of urban planning in order to generate both climatic and social benefits. Following on from this, the research question is: What impulses can new urban climate data and data on the perception of climate change in public places in Heidelberg provide for sustainable urban development? The transdisciplinary approach is based on the combination of different methods of physical as well as human and social geography, the involvement of urban actors and citizens and the concept of research-oriented teaching. The latter creates a learning environment in which students can experience the current problems of urban development in times of climate change and actively participate in the development of solution and adaptation strategies. In cooperation with the Environmental Office of the City of Heidelberg, current issues of urban development adaptation to climate change are to be researched transdisciplinarily and also prepared for teaching in teacher training. The evaluation of the overall data set shows current trends in climate change development. In the summer of 2018, many parts of the city exhibit severe heating and drought. Measures that have a regulating effect on the microclimate are in co-benefit with the respondents' wishes for shading, greening, diversity and a general improvement in the quality of life in public places such as the University square or the Schwetzinger Terrasse. These adaptation measures are essential from a scientific point of view.
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