Rediscovering the urban realm and open spaces (RUROS)

Based on substantial measurements in several urban open spaces in the EU, a system for objectively describing the soundscape and acoustics environment is being established. The indices include reverberation, sound pressure level, spectrum, sound source direction, and so on. Corresponding to the acoustic indices describing the soundscape in urban open spaces, methods for making measurements and representing results are being established. Measured indices include reverberation, sound pressure level, spectrum, sound source direction, and so on. An overall system for describing soundscape and acoustic comfort in urban open public spaces is being established. The description includes four parts, namely characteristics of each sound source, acoustic effect of the space, social aspect, and other aspects. Based on substantial literature review in relevant areas and pilot study in several urban open spaces in the EU, a questionnaire and a soundscape form for subjectively evaluate soundscape in urban open spaces are being established. Semantic differential analysis has been used for developing such a system. Part of the soundscape questionnaire was included in the questionnaire for physical comfort in urban open spaces, used for the large-scale survey in 12 urban open spaces in the EU. Two computer models have been developed for predicting acoustic indices in urban open spaces, including reverberation, sound pressure level and so on. The models are based on radiosity method and image source method, respectively. In the mean time, commercial software based on ray-tracing and noise-mapping techniques have been applied for urban open spaces. Based on the subjective survey and objective measurements, as well as a series of parametric study using the computer models, design guidelines for good soundscape and comfortable acoustic environment in urban open spaces are being developed. Various scales are considered, from planning to detailed soundscape elements.

In the pilot applications the design guidelines will be implemented in two open spaces in Greece. This is the final stage of the RUROS project and will be started as soon as the analysis of the microclimate (thermal, visual, acoustical environment) and the morphology of the open spaces as well as the design guidelines are completed. The implementation of all results produced by the RUROS project is very important, because it represents the transition from theory to praxis. More specifically, any inefficacy or weakness of the software or the guidelines developed through the stages of the RUROS project will be tested in praxis and, consequently, the encountered problems will be solved accordingly.

A methodology has been proposed to evaluate outdoor thermal comfort on the basis of comfort indicators and input of mean radiant temperature derived from radiant field calculation (through Solene). The method allows evaluating design proposals of urban spaces refurbishment as well as urban spaces new development.

The raw data, obtained from the case study surveys and interviews has been made widely available over the Internet. The database includes microclimatic data and corresponding results of the questionnaires regarding the thermal, visual and acoustic environment, as well as information on the use of outdoor space and social character, from 14 different open areas from 7 European cities (Alimos in wider Athens, Thessalonica, Milan, Fribourg, Kassel, Cambridge and Sheffield). Each site has been monitored throughout the day for a whole week per season, in all four seasons, in order to obtain the dynamic temporal variation required. This data set, with over 10,000 interview records, will be useful for future reference of similar projects, so that eventually a whole database can be constructed with comfort studies from around the world, to provide immense support and backup for future studies.

Resulting from the RUROS project, a series of refined technical methods have been developed in order to design open spaces with better bio and micro-climate conditions for the users and inhabitants. When emphasis is given to physical micro-climate dimension at the design process, the risk could be to concentrate the design interest to some particular factors in spite of others. Therefore it is important to envisage all aspects of the function of the open space into its social and urban environment and to have indices for the relative importance of each aspect as citizen concern. In that order, indicators related to social considerations within urban design process of open spaces have been developed. They are a series of quantified values showing relations between social and economic development and the development of open spaces that have been related to assist the comfort design of open spaces. They are part of the research results arisen from field surveys in selected case study sites within European urban environments and methodological analysis. They indicate separately each aspect of the overall functioning of a specific open space but in a common manner for any type of open space. In that way the indices are significant for the specific open space and for its type. Therefore, urban planning studies based on social surveys using this research tool arisen from RUROS project, will contribute to the European approach for the development of open spaces in the European urban context and environment.

For finding issues and indicators related to the contemporary open spaces that link together the overall function of urban open spaces and the descriptive data of specific sites with the urban design process, a methodology has been developed in the framework of RUROS project. Based on empirical results, this methodology can be used in the framework of a research programme to compare different case study sites. It can be used in the framework of urban studies as well, which have the intention to describe and evaluate open spaces basing on social survey. This result comprises: (a) the research procedure related to comfort design of urban open spaces, (b) the analysis phase within the design procedure that interrelates social issues and physical properties of contemporary open spaces by means of a classification and articulation system and (c) the evaluation tool. The purpose is to insert operationally the perceptual levels of users and inhabitants within the design procedure of professionals as planners, architects, and decision takers.

The environmental parameters that have been identified as playing a major role on the comfort in the urban context at a neighbourhood scale are those that are directly affected by the microclimatic alterations that urbanisation causes. The key microclimatic factors include temperature (heat island effects), solar exposure, wind movement, the acoustic environment and urban noise propagation. Urban morphological analysis can primarily contribute to temperature, sun and wind analysis, as well as providing insights in to noise propagation issues.

Multistereographic projections are a new graphic method that allows a precise evaluation of the solar access (or shading) of a large outdoors area by surrounding buildings and/or vegetation. The projections are made by dedicated software built around the RADIANCE ray-tracing package.

Design guidelines will be produced for the development of open spaces, in the form of "best practice" guides. These will be useful for the design of sustainable open spaces with emphasis on the comfort of the users, for all professionals related to the design of open spaces, architects, urban designers, planners, etc. Additionally, they can be employed by Municipalities and other public authorities as a guide for the design of redevelopment of open spaces. Such advise will also be useful for professionals coming from different disciplines, such as engineers, or even physicists, biometeorologists, and all professions working with urban climatology and the urban context, and whose decisions can influence the urban microclimate. Furthermore, this will be translated to different languages from the different contractors for effective exploitation and acceptance by municipalities and the wider public.

Human monitoring is a very important process for the evaluation of comfort conditions in open spaces. For that a questionnaire has been developed examining the thermal, visual and acoustic comfort conditions of users of open spaces, as well as other parameter, which affect the use of open space. This allows studying of people in their natural environment through observations and personal interviews, to evaluate their perception of the thermal, visual and acoustic environment and its importance for the use of space, a critical parameter for developing sustainable urban spaces and cities.

It is vital to have information about air velocities and air patterns when assessing comfort conditions on outdoor spaces. Data can be obtained through full scale monitoring on site or through wind tunnel tests, but both solutions can be very costly. Another way to obtain data is to carry out CFD calculations of the concerned space. This however requires a methodology, as CFD is a very calculation heavy type of software. CFD (Computational Fluid Dynamics) is a computer simulation tool used to calculate flow data for different kinds of fluids. CFD could be used for studies of the water flow in a river stream, the air movement in an urban space or other fluid situations. The governing flow equations are the Navier-Stokes equations for transport of mass, momentum and energy. If the flow is turbulent an additional set of transport equations is needed. Since the equations are highly non-linear and coupled they are too complex to be solved by simple calculation. Therefore, in order to analyse a specific fluid situation, it is often necessary to use either experimental data (measurements on site or in a wind tunnel) or numerical data from CFD. Through the last decades computer technology has developed rapidly and made it possible to simulate fluid motions in such ways that the results are very much in accordance with existent fluid situations. CFD can therefore be used as an advisory tool, which presents a realistic picture of a certain flow situation. The most significant features of CFD are the very big model files and the very long calculation time - the bigger model file, the longer time it takes to calculate. Therefore many CFD users try to decrease the size of the model in order to reduce the calculation time. This often leads to a com-promise in the detailing of the model. Therefore it is utterly important to be aware of how to prioritise during modelling, i.e. which sections requires detailed modelling and which sections do not, in order to obtain reliable results. The basic principles in using CFD are: - Model building - definition of a control volume (the river or the urban area) and what is in it (e.g. rocks or buildings; - Boundary conditions - what comes in and what goes out of the control volume; - Generating a mesh - divides the model in to smaller pieces; - Validation of the model - a check to assure the reliability of the model; - Calculations; - Evaluation of results. Most times there is an iterative procedure from the model building to the validation of the model; the model is often revised several times in order to find the optimal model. The methodology describes these principles in detail and demonstrates the principles on two specific example studies.

Evaluation criteria for the triptych functions-uses-activities of open spaces: The study of the results obtained in the Social Survey of the project RUROS es regards the general notions of 'function'/'uses'/'activities' and their Empirical contents to be used as a series of parameters.

Appropriate monitoring techniques have been identified for monitoring the thermal, visual and acoustic environment. The monitoring equipment has been designed and constructed in an innovative way, in order for it to be portable. Environmental monitoring involves the thermal microclimate measuring air temperature, solar radiation, wind speed, humidity, the visual environment measuring horizontal and cylindrical illuminance, and the acoustic environment measuring sound pressure levels. All the sensors are connected to a data-logger to store the information for the recorded period. By placing the equipment near people it is possible to monitor the conditions experienced by users of open spaces, throughout the space, allowing evaluation of comfort conditions in urban spaces.

A simple cylindrical illuminance sensor has been developed. With the data from the field surveys collected during this project, we hope to demonstrate that cylindrical illuminance is a better visual comfort indicator in outdoor spaces than the usual horizontal illuminance. If this proves to be true, the cylindrical illuminance sensor we have developed could be of interest to other teams who plan to perform similar field studies.

Simplified models to predict thermal comfort conditions in outdoor urban spaces, using publicly available meteorological data. These can have the form of a "City Comfort Index". To evaluate the effect of different design conditions, e.g.to distinguish between sunny and shaded areas, or areas protected and exposed to the wind, simple correction factors can be introduced on comfort models for design purposes. These are particularly useful for urban designers, architects and planners, as well as decision makes evaluating design proposals.

On the basis of field surveys and an accompanying extensive dataset concerning comfort conditions, use of outdoor space and social character of two public open spaces in Kassel a methodology for mapping thermal comfort conditions in the urban context has been developed. The most important issue was to focus on an easy-to-use and easy-to-understand tool/methodology addressed and dedicated to the special interest/needs of planners and architects. The first step towards thermal mapping was analyzing the spatial distribution of meteorological parameters and comfort indices (PMV, PET) as well as comfort evaluation of interviewees and use of space of the sites in Kassel. Out of this thermal comfort zones could be derived. This procedure was based on the field survey results and therefore depends on the availability of respective data. In consequence, for a more general use in the context of urban planning, it has been derived a "simple" methodology based on the main influencing parameters and widely available data. The most important aspect is taking into consideration three main issues: morphology of the site (geometry of buildings, kind of surfaces (ground / facades), vegetation), meteorological parameters and time parameters. Concerning meteorological parameters there is a focus on solar/thermal radiation and wind speed. These two aspects have a high spatial and temporal variation, whereas air temperature and vapour pressure are more homogeneous. So radiation and wind speed are the main influencing factors in producing different comfort situations within one site at the same time. In the end a spatial distribution of zones with similar comfort conditions can be derived, followed by an evaluation in terms of risk or suitability. In this context the design and use of open space are considered as influencing factors/variables acting in two different "directions"; on the one hand they influence the mapping and evaluation results, on the other hand from the evaluation there can arise the need for changes/adaptation in design, use of space etc. All in all, a methodology of drawing comfort maps has become available, which can be applied to any site in a very simple and effective way (instead of complicated and time/money wasting modelling). From the comfort maps a predicting comparison and assessment between different alternative design conceptions can be achieved which is devoted very much to the need of urban planning and related fields (e.g. energy, traffic, air pollution etc.). Moreover a characterization and assessment of different city structures as well as climatic and urban patterns can be derived. So the methodology of drawing comfort maps enables and contributes to the improvement of urban quality of life in the context of environmental friendly cities and provides a useful tool for engineers and local authorities.

The development of the methodology for morphological analysis for microclimatic performance will greatly enhance the task of analysing the factors that influence comfort conditions and microclimate in outdoor urban spaces. This methodology can then be applied to the formulation of design guidelines for the case study sites, as well as other urban studies.

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