Urban Climate. Prof. Dr. Lutz Katzschner Environmental Meteorology Department Faculty of Architecture and Planning University Kassel / Germany

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1 Urban Climate Prof. Dr. Lutz Katzschner Environmental Meteorology Department Faculty of Architecture and Planning University Kassel / Germany Urban Climatology and Global Climate Change - air pollution aspect (toxic health risks), change of radiation followed by change in the chemical reactions in the atmosphere (NOx and Ozone) - thermal aspect, urban heat island (health risks through heat stress) - meteorological extremes (rain, duration of hot days) Climate Protection Emissions (green house effect) Global effects Regional climate Climate Adaptation global climate change Regional effects Urban climate (buildings/orientation/density)

2 Urban Climate Recommendations: Heat load: radiation from facades, shadow, cooling surfaces,thermal ventilation (zoning plans), ventilation (urban development plan)

3 Objectives Strategies Actions Planning Time Scale Spatial Scale Albedo Cool material-building & pavement; Cool roof & facade; Water retention paving; Short term Material & Surface Level Intervention Marco Effect UHI Thermal Comfort + Air Pollution Air Quality Vegetation Shading Ventilation Planting & greeneries; Parks & open spaces; Building geometric design; Shelter design; Street orientation; H/W ratio; Trees; Air paths; Building ground cover & building bulks; H/W ratio; Street orientation; Open spaces; Building disposition; Building Level Intervention Urban & Planning Level Intervention Long term Micro Effect

4 Effect of shading on mean radiation temperature during a summer day in Freiburg

5 Gleiche Randbedingungen, Links: Innenhof mit Gras + Bäume Rechts: Versiegelt Urban Climatic Mapping

6 Urban Climatic Mapping GIS layers Layer structure of UC-AnMap Buildings Landuse Topography Building Volume Topography Green Space Ground Coverage Natural Landscape Proximity to Openness + Thermal Load Dynamic Potential Draft UC-AnMap Further wind Information Final UC-AnMap + =

7 Calculation layers in GIS Layers urban climate aspect data used classification with weighting factors A building volume heat storage building information and land use in m 3 building volume B built up areas and openness heat storage and ventilation building information and land use % relation of built to non built areas C cold and fresh air production, green areas heat balance of surfaces production of fresh and cool air, influencing neighbourhoods land use classification, surface conditions in m 3 /m 2 *h as cooling rate D roughness, air paths and ventilation land use, openness, use of background wind and local circulations land use and openness surface data z o derived from the wind profile E slope analysis, downhill movements relief energy for thermal induced circulations digital elevation model in percent slope inclination

8 UCM Arnhem Cool air production zones Fresh air production zones Mixed areas moderate urban heat remarkable urban heat island urban heat island maximum air paths for areas for thermal classification background wind and induced thermal induced circulations ventilation pattern 1) train track a) dense row houses 4-5 storeys a) city a) inner city wind information from urban climate map a) regional wind using air paths 2) residential areas, urban edge b) less dense row houses three b) office, low industrial but b) industry high including sub layer situation, transition zones 3) parks areas to four storeys ventilated c) row houses as before up to 10 storeys d) low rised buildings max. 3 b) thermal induced circulation c) downhill winds turbulences storeys Open areas with Open areas with less strong daily variation through some heat storage but mainly heat storage remarkable but still heat storage high and low background and thermal winds and significant climatic significant climatic activity; income radiation, but good buffered through greeneries and some wind effects and cooling cooling potentials and low regional winds slope circulations climate description activity, cool and fresh air production; climatically active open sites in direct relation to the housing area; in fresh air production cooling effect wind potentials ventilation combination to slopes very effective morphology All areas with vegetation All areas with vegetation including parks and here mainly agriculture, forests parks and gardens, no pollutions sources Train areas as well as small small housing areas all with low more dense and higher building housing areas, the built up areas heat storage but with some heat but still some cooling effect with linkages to surroundings load, either through greeneries or wind densely build up areas with high Open areas with low Open areas with percentage of concrete, roughness, used for some buildings but ventilation rather low background winds affected by thermal induced circulation such as cool and fresh air movements High sensitivity with The increasing surface important linkage areas, forsee No appreciable sensitivity in Risk of future heat stress due to In need of renewal from the respect to intervention roughness (e.g. further the orientation and density, terms of climate with respect to the neighboring green areas, point of view of urban climate. which changes in land constructions or buildings) surface roughness cannot be intensification of use and some dynamic potential are Greenery for facades and use. Do not allow can only be allowed if they increased due to a reduction in building agglomeration. existing. So generally the areas surfaces are needed. evaluation increasing the surface respect slope winds and ventilation with the effect on roughness (e.g. no further thermal induced circulation neighbourhoods constructions or pattern; furthermore, buildings). Keep open of Redevelopments should be cold/ fresh air stream; allowed only in exception Minimize the existing case, which is supported by barrier on the air streams. detailed investigation and The air movement analyze on climatic connections must be fully function aspect. analyzed and understood including the source of the air stream channels, Generally redevelopment is possible if they take care about ventilation. should be maintained or improved, and not worsen. Increasing of existing heat Development can only be stress, due to the accumulated allowed with the compensation problems on thermal load in the for climate effects. The existing high dense built-up area, the air circulation should be climatic condition of this zone analyzed before any proposed should be improved. No more change so that the urban climate development in this zone is is respected allowed. Improving air exchange is one major recommendation together with shadow providing design. which may be far away from the concerning area. Evaluation of results by measurements from 19th August 2009 University Wageningen

9 Results from air temperature ( o C) measurements 19. August 2009 evening situation Arnhem (22:00) Results from air temperature ( o C) measurements 19. August 2009 midday situation Arnhem ( :00)

10 Results from wind speed (m/s) measurements 19. August 2009 Arnhem route evening midday Adaptation measures: ventilation

11 Urban climate improvement: - improving ventilation through air paths or thermal induced circulation; - reducing urban thermal load (heat island) and air pollution