Zoekresultaten

The cooling effect of different water bodies in Amsterdam during hot days

Urban green and shading are adaptation measures that reduce urban heat. This is evident from meteorological measurements and investigations with surveys and has been described in many papers (e.g. Klemm et al., 2015). The cooling effect of these adaptation measures is reflected by lower air temperatures and an improved thermal comfort. Shading and urban green are also experienced as cooler than impervious urban spaces without vegetation or shading. However, the cooling effect of water bodies in cities, such as rivers, lakes, ponds, canals,fountains, is not clear yet (Steeneveld et al., 2014). Several studies show that the cooling effect of water bodies in cities is small, or can even be a source of heat during nighttime. The effect depends on the characteristics of the water body and the meteorological conditions. Nevertheless, water is often mentioned as an adaptation measure to reduce urban heat.To support urban professionals in designing cooler urban environments by using water bodies, we investigated in more detail how different water types in msterdam contribute to cooling the environment. During five summer days, we measured the cooling effect of five different water bodies: a pond, a fountain, a canal, and two rivers. We used measurements from mobile weather stations (air temperature, relative humidity, wind speed, global radiation and globe temperature) and collected almost 1000 surveys near the water bodies and a reference location. From these data, we could determine the effect of the water bodies on air temperature, thermal comfort and thermal sensation. The research question that we tried to answer with this study is: What is the cooling effect of different water types in the city of Amsterdam during hot days? The study has been carried out within the framework of a Dutch research project ‘Urban climate resilience – Turning climate adaptation into practice’ and supports urban professionals to decide on the right adaptation measures to reduce urban heat.

Cooling Urban Water Environments: Design Prototypes for Design Professionals

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.

Are urban water bodies really cooling?

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.

Hoe verkoelend is water nu echt?

Stadsontwerpers werken graag met water. Een van de voordelen zou zijn dat waterelementen hitte in de stad verminderen en de gevoelstemperatuur op straat verlagen. Maar hoe verkoelend is stedelijk water nu echt? Volgensverschillende studies is een verkoelend effect van watervormen zoals vijvers, grachten en sloten nauwelijks merkbaar of zelfs afwezig.

Water in en om de stad

Eindrapport KIEM-CE Project WOW - Waste-On-Water

In de binnenstad van Amsterdam wordt door infrastructuurproblematiek en het drukke verkeer de problematiek van bedrijfsafvalinzameling nog meer uitvergroot, naast dat de gemeente uitgesproken ambities heeft voor emissievrije stadslogistiek en de ontwikkeling van de circulaire economie. Daarom onderzoekt de gemeente met partners die actief zijn in afvalinzameling hoe gescheiden afvalstromen collectiever, kleinschaliger en frequenter ingezameld kunnen worden en met behulp van emissievrije, elektrisch aangedreven en lichtgewicht logistieke oplossingen wordt onderzocht. Één van de pilots betreft bedrijfsafvalinzameling over water in het wallengebied en is gerealiseerd door gemeente Amsterdam afdeling bedrijfsafval, afvalverwerker Renewi, logistiek bedrijf ZOEV City en sociaal leer-en werkbedrijf Pantar. Het restafval van een aantal bedrijven wordt door kleine elektrische voertuigen lokaal ingezameld en met een stuwboot naar de verwerker gebracht in plaats van inzameling door de gebruikelijke dieselvuilniswagen.In dit project onderzochten we hoe we een gezamenlijk ontwikkeld businessmodel voor deze nieuwe wijze van inzamelen in de case rendabel kan zijn voor de stakeholders. En we onderzochte hoe het bij kan dragen aan emissievrije logistiek, minder verkeersdruk, leefbaarheid in de omgeving, minder onderhoud aan de kademuren en een verbeterde afvalscheiding voor hergebruik in de circulaire economie. Het rapport laat zien hoe open collaborative business modelling, gecombineerd met impactmetingen kan helpen bij het ontwikkelen van oplossingrichtingen voor nieuwe circulaire samenwerkingsverbanden.