URBAN CLIMATE SPACES A Multidisciplinary Research Project

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1 URBAN CLIMATE SPACES A Multidisciplinary Research Project Ulla Westerberg *, Igor Knez *, Ingegärd Eliasson ** * Department of Technology & Built Environment, University of Gävle ** Department of Physical Geography, Göteborg University Abstract Urban Climate Spaces 1 is a new research project integrating architecture, psychology and climatology. This paper roughly describes background, multidisciplinary approach and methodology. The aim of the project is to investigate the influence of the microclimate on how urban public spaces are appreciated and used and how city life is influenced by the local climate. A further aim is to make the results applicable in urban design. Behavioral and climate data are collected on different spatial and temporal scales. Case studies in public spaces are carried out in the centre of Göteborg in the south of Sweden, 58 N. The same data collection will be made in Luleå, 66 N. Comparison between different urban spaces, between the two cities, between different weather situations and seasons etc. - is the mode of analysis. Keywords: Urban microclimate, climatic design, place identity 1. INTRODUCTION Climate and weather are an attraction and an obstacle in outdoor staying. Urban life today is concentrated to certain times and certain places where optional (leisure) activities seem to dominate. Many traditionally outdoor functions have been built in to be independant of season and weather, such as shopping areas and sport facilities. On the other hand people crowd in open air cafés under heaters, wrapped up in blankets to prolong the short season an urban phenomenon that is new in cold climates. The short time spent outdoors makes it the more precious. Sun or shade, exposure or shelter from the wind, etc. make the public urban spaces more or less suitable for different purposes. The microclimate is a property of the environment; a consequence of the surrounding physical elements. It is an aspect of form that could be intentionally used to accentuate architectural qualities also beyond the rising demands of thermal comfort. In a new project we are exploring the climate dimension in the design, use and meaning of the urban environment. We are studying how climate and weather influence urban life. We want to find out what climate parameters are the most important and how they are related to built form. We will develop arguments and tools for climatic planning to be applied in urban design. There are but few studies on the people-climate relation focusing on the outdoor climate. Jan Gehl 2, a pioneer in this respect, very strikingly showed the importance of microclimate for social life by counting people sitting on sunny and shady benches. A recent example is a study of plazas in Montreal 3, where the microclimate has been measured and activities have been observed. The validity of national climate criteria for the outdoor environment was tested in housing areas in different parts in Sweden using questionnaire surveys and climate modelling combined with full scale measurements 4. The project discussed here is unique in that it combines all these methods and perspectives. In this paper we describe the time-space structure of the data collection and analysis Jan Gehl, Livet mellem husene, Köpenhamn. During the 1980.ieS AND 90.ies Gehl has followed up these early observation studies with similar ones where climate and weather is one of several important environmental factors. 3 John Zacharias, Ted Stathopoulos, Hanqing Wu, Microclimate and downtown open space activity, Environment and Behaviour, volume 33 nr 2, March Ulla Westerberg & Mauritz Glaumann (1990). Design Criteria for Solar Access and Wind shelter in the Outdoor Environment. Energy and Buildings, (1990/91)

2 2. A MULTIDISCIPLINARY APPROACH The physical attributes of space, climate and weather influence people directly through physical processes and indirectly through imprints on the physical environment like snow, whistling of the wind, reflections etc. The climate is seen, heard and sensed. It is sensed principally as heat or cold, i.e. thermal comfort. (Comfort may also refer to wind, light and noise) and it more or less consciously influences physical activity. The characteristic microclimate is a property of an urban space that has a considerable impact on the range of possible activities and the actual use of it. The microclimate thus contributes to its meaning and identity. Comfort, use and meaning (cognition, emotion) represent three perspectives of the people environment relation here referred to as behavioural. Climate denotes average and typical long-term weather conditions whereas weather describes a particular situation or a short time interval. Geographical position latitude, altitude, surrounding landscape etc. determines the local climate of a city or region. Buildings, vegetation and topography, anthropogenic heat, etc. influence the climate in the scale of people and buildings and create climate spaces with a characteristic urban microclimate that deviates more or less from the local climate. The local weather is measured so as to represent an average for a larger area, and the weather that is directly sensed we call the microweather. Climate and weather refer to parameters such as temperature, radiation, wind, and precipitation Urban microclimate and identity of place The microweather that people experience instantaneuously in streets and plazas deviates more or less from the local weather. When it is sunny or windy the deviation is bigger and when the scale of the surrounding is big, i.e high buildings or large open areas, it is also big. Variations in general attracts the attention. Special climatic features may underline other impressions and evoke associations to other feelings. The strong winds in an open square, for example, could amplify a spatial feeling of desolation or the social feeling of being exposed. The wish for wind shelter on a windy spot may also be a wish for shelter against other things, e.g. other people s viewing. Not to forget the strong underlying physical demand for thermal comfort. The variations in the microclimate may be rather big during the sunny and windy days, but averaged over the dull and grey days they may be rather insignificant. Our hypothesis is that the memory of places that we visit fairly often is not an average but the typical differencies between and within places. The urban spaces become urban climate spaces in the mind. We beleive that people more or less consciously develop an understanding of how climate and physical surroundings are related, i.e. that windiness could be associated with wide views and freedom. We beleive that places awaken certain moods and that the microclimate may be an important generator in the process, (see Knez 2003 a 5 and Knez 2003 b 6.) 2.2. Local climate and urban culture How ought meteorological data to be characterised with special reference to local habits and views on climate and outdoor staying? What is the climate that people bear in their minds? The individually sensed and experienced climate influences instantaneous and comprehensive assessments as well as socially and culturally transferred knowledge, ideas, predjudice and habits related to the climate. Clothing and outdoor sports are such habits which are in constant change for many reasons. Interacting with the physical and cultural environment the individual develops and incorporates new concepts and beliefs more or less related to the local climate. To what extent do we share the same history living in the same place? People are mobile, within the city and between cities and regions, and climate cultures and subcultures from different times and places are mixed. Large individual differences in people s climate assessments and experiences as related to the cultural constructions of climate could therefore be expected. Childhood landscape, outdoor habits, housing situation, etc. may shed a light on these differences together with demographic factors such as age and gender. At a group level, however, interpersonal experiences of the climate are expected that renders not only urban places, but also cities and regions unique climate identities. The aim of this project is not to reduce the problem to a single figure, i.e. to an extended comfort index, but to elaborate it in a number of measurable aspects. One way is to base the analysis on the weather that people have really experienced. Direct experiences of climate and places are expected to have a greater impact the closer they are in time and space. The extreme situations the good and the bad weather - probably make a stronger impression than the more average situations which dominate in time. 3. OUTLINE OF DATA COLLECTION Similar urban spaces in the city centres of Göteborg and Luleå have been chosen for case studies. They roughly represent a sequence of places from natural to manmade when it comes to climate: part of a park and a water 5 Igor Knez 2003 a, Climate a nested physical structure in places, 5 th International Conference on Urban Climate, Lodz 6 Igor Knez 2003 b, Memories for climate and places, 5 th International Conference on Urban Climate, Lodz

3 SHORT TIME WEATHER LONG TIME - CLIMATE MICRO - URBAN SPACES Problem: How is the urban microweather perceived in terms of comfort? How does it influence the use of the spaces? How relevant are different comfort indices as a characterisation of the microweather? Behavioural data, case study: Observed use of selected spaces, direct assessment of comfort and windiness, assessment of affect or mood in short interviews Climate data: Field measurements of wind, temperature, radiation Problem: What is the importance of the urban micro-climate for the identity of an urban (climate) space? Methods to characterise and present the urban microclimate in planning. Behavioural data: Survey and telephone interviews on the attitudes to, memories for and use of selected spaces. Climate data: Theoretical calculations of spatial and temporal variations based on field measurements, wind tunnel studies, studies on skye view factor and solar access, etc. MACRO (LOCAL) - CITY - REGION Problem: How does the actual weather influence outdoor staying and attitudes to weather and climate in general, i.e. reported or observed behaviour? Most behavioural data ought to be controlled for the actual weather situation Climate data: Weather during april 2003 and case studies from standard met station and reference station Problem: What is the importance of local climate in urban life, how does it affect outdoor staying and use of public places? What is the importance of the weather history? Behavioural data, survey and telephone interviews : Assessments of local climate, views on climate, weather and outdoor staying, time and purpose of outdoor staying Climate data: from standard met station and reference station Table 1. Research problems and behavioral and climate data are summarised in a time-space matrix so as to point out their dynamic, processual character. Behavioral data is matched with climate data of the same time and space scale. front space, an open plaza and a courtyard. A climatised public place (shopping mall) has been chosen as a reference with no sophisticated climate measurements. A questionnaire survey has been carried out in Göteborg, followed up by telephone interviews. People working or living in the centre have been asked about their habits and attitudes towards outdoor staying, climate and weather in general and habits and attitudes concerning the urban spaces in the case studies in particular. The case studies include observations on what people do and short structured interviews about the reason for being outdoors, the current weather, assessments of the actual place and its microclimate, their mood. The case studies cover four time periods and are accompanied by full scale measurements of wind, temperature/radiation. Windtunnel studies and skye-view analysis will be carried out. Standard observations are made continuously in a nearby reference mast, and in addition longterm statistics from several permanent meteorological stations. 4. A TIME-SPACE ANALYSIS The experienced weather is assumed to differ from the standard meteorological description of the climate. Basic for the discussion of the cultural construction of climate, however, is the weather people have actually experenced i.e. where they have been, at what season and what time of the day, and not least what they have been doing. This is the starting-point of the analysis as shown in the time-space matrix comprising the dimensions that are used to describe the climate.

4 SHORT TIME WEATHER LONG TIME - CLIMATE MACRO (LOCAL) - CITY - REGION MICRO - URBAN SPACES Reference station mall frequency % Wind direction and wind speed (m/s) 30 year mean Göteborg airport NE E SE S SW W NW N CALM wind direction Figure 1. Example of wind data in different scales in space and time (see table 1) and their relation to each other. Micro weather: Field measurements of wind direction, velocity, turbulence intensity are made during four 10-day periods in four selected urban spaces in Göteborg (picture from Gustav Adolfs torg). Micro climate: Measurements of relative wind speed have been made in the building aerodynamic wind tunnel of the university of Gävle to which the case study measurements are linked via a reference station. The picture shows the wind pattern within the marked area illustrated by shades of grey, i.e. the whiter the less windy. (Superimposed model photos of gradually blown away semolina grains). Macro weather: The reference station is located within the area (and in the wind tunnel model) measuring the weather 10 m above the roofs connecting the model and field measurements. The air photo also shows the other three selected urban spaces: 1 sea front plaza, 2 court yard, 3 big plaza (in the photo and wind tunnel test), 4 park. It also shows the shopping mall which will be used as a reference. Macro climate: The long-term statistics from the meteorological stations are used to calculate the microclimate via the reference station. The diagram shows the 30 year means, which may be adequate in weather forecasting and planning but maybe not to describe the local climate that people remember. Climate and behavioural data are analysed on the same spatial and temporal scale. Behavioural data in different scales are analysed in relation to each other, i.e. how activities, attitudes, experiences influence each other on different levels from the individual activity to the shared habits and values. The regular diurnal and seasonal changes of the climate make the processual nature of the use and meaning of places visible. The random change

5 of the weather, however, is a nuisance in theory as it is in the case studies so that good theories are very important to bridge the data gaps and contradictions.