Due to climate change, rising temperatures lead to more extreme heat stress in urban areas. Last summer, there were poignant images of people looking for shade in cities. Trees are effective measures to provide shade and decrease the perceived temperature. However, trees cannot grow in healthy conditions due to the conflicting interests of the many functions and infrastructure in cities. Also time is a limiting factor; before trees are fully grown and can fulfil its various functions (shade, biodiversity, appearance), it takes not only physical space but also time. Alternative interventions, such as a pergola, can help increase urban resilience by reducing the negative impacts of climate change.Pergolas are known, for example, in more southern Europe cities. However, despite the described promising effects of the pergola in documents to reduce heat stress and provide shade, we barely see these structures in the Dutch public space. We all know the pergola as an esthetical piece in the backyard where it provides shade, privacy and contributes to well-being, but they are not widely used in the public realm.Next to that, there are few or no known preconditions for an urban pergola. The functions that an urban pergola can offer go beyond providing shade. The pergola might help reduce noise and pollution, provide a meeting place in a neighbourhood and support biodiversity. Since space is scarce in cities where many different interests come together, we want to explore the potential contribution of an urban pergola to different problems. Therefore, at the Amsterdam University of Applied Sciences, we have worked on an urban pergola as a real 'boundary object' where we bring education, research, municipalities, and entrepreneurs across disciplines and sectors together to discuss the potential of such an object.For this workshop, we would like to show our first results of this interdisciplinary action research and continue answering the question: how can a pergola fit in the Dutch urban area? Therefore, we would like to explore the functions and forms of the urban pergola with stakeholders, such as municipalities, entrepreneurs, citizens, students, and researchers all from different disciplines. The desired outcome of this workshop is a joint proposal for implementing urban pergolas that can meet the versatile needs of cities and thereby make cities more liveable.
MULTIFILE
This paper presents five design prototypes for cool urban water environments developed in the 'Really cooling water bodies in cities' (REALCOOL) project. The REALCOOL prototypes address an urgent need: urban water bodies, such as ponds or canals, are often assumed to cool down their surroundings during days with heat stress, whereas recent research shows that this is not always the case and that urban water bodies may actually have warming effects too. There are, however, indications that shading, vaporising water, and proper ventilation can keep water bodies and their surroundings cooler. Yet, it is necessary to explore how these strategies can be optimally combined and how the resulting design guidelines can be communicated to design professionals. The REALCOOL prototypes communicate the spatial layout and biometeorological effects of such combinations and assist design decisions dealing with urban water environments. The micrometeorological simulations with Envimet showed that the prototypes led to local reductions on daytime PET from 1 °C to 7 °C, upon introducing shade. Water mist and fountains were also cooling solutions. The important role of ventilation was confirmed. The paper discusses and concludes about the use of the prototypes as tools for urban design practice.
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Small urban water bodies, like ponds or canals, are often assumed to cool their surroundings during hot periods, when water bodies remain cooler than air during daytime. However, during the night they may be warmer. Sufficient fetch is required for thermal effects to reach a height of 1–2 m, relevant for humans. In the ‘Really cooling water bodies in cities’ (REALCOOL) project thermal effects of typical Dutch urban water bodies were explored, using ENVI-met 4.1.3. This model version enables users to specify intensity of turbulent mixing and light absorption of the water, offering improved water temperature simulations. Local thermal effects near individual water bodies were assessed as differences in air temperature and Physiological Equivalent Temperature (PET). The simulations suggest that local thermal effects of small water bodies can be considered negligible in design practice. Afternoon air temperatures in surrounding spaces were reduced by typically 0.2 °C and the maximum cooling effect was 0.6 °C. Typical PET reduction was 0.6 °C, with a maximum of 1.9 °C. Night-time warming effects are even smaller. However, the immediate surroundings of small water bodies can become cooler by means of shading from trees, fountains or water mists, and natural ventilation. Such interventions induce favorable changes in daytime PET.
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