Thesis document - Jana Milosovicova - Urban Design English

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However, greening of surfaces and albedo rising are not the only aspectsthat significantly influence the energy balance of cities. The naturalwater cycle and (rain)water management are another issues to beconsidered when pursuing climate-sensitive urban design.“Water and water vapor influence inthe most significant way the climate onEarth” (Kravčík et al. 2007, p. 14).Water cycleIn the natural environment, about 75% of rainwater evaporates fromthe land and thus stabilizes the climate and the temperatures. In urbanareas however, as pointed out before, the lack of evapotranspiration isa major cause of the urban heat island – and thus the evaporation ofrainfall should have the highest priority (SenStadt Berlin and TU Berlin,p. 11). The consideration of water – in fluid form or as water vapourincreasing the air humidity – has however been widely underestimatedand overlooked in urban design considerations. In this section, it willbe reported on the importance of water and possibilities of restorationof the small water cycle through urban design.The small water cycle (fig. 17) is characteristic for a hydrologicallyhealthy country, where solar radiation evaporates water from waterbodies, soil and plants into the atmosphere. There, water representsthe largest energy conversion of incoming shortwave solar radiation,playing an important role: “the less water in the atmosphere, theweaker its moderating effect on temperatures” (Kravčík et al. 2007, p.14). The majority of evaporated water in the atmosphere condensesand falls down again at night in the given region or its surroundings –alleviating the UHI effect, whose intensity is most significant at night.In urbanized, built-up areas, there is an extensive disruption of evaporativevegetation cover and of permeable surfaces (fig. 18) and thus,a high proportion of the rainwater is led into the sewerage, instead ofbeing evaporated. “Nearly all rainwater from the cities of Europe is carriedto rivers and eventually to the seas from paved and roofed areasby rainwater sewers” (Kravčík et al. 2007, p. 43-44). To illustrate thesituation in one particular city, only in Berlin it is annually 35 millionm 3 (SenStadt – Rainwater I, online). The effects are a longterm drop ingroundwater supplies beneath the paved and roofed surfaces, a fall inatmospheric humidity and cloudiness 15 and a decrease in light and frequentprecipitation (Kravčík et al. 2007, p. 17-18, 44). All this affectsthe natural water cycle, leads to an increase in urban temperatures andcontributes to other serious problems such as floodings, extreme heatsand droughts (Sass, online). The physical impact of cities on small watercycle might be observed in the figure 19.Fig. 17 The small and large water cycle(Kravčík et al. 2007, p. 20)Fig. 18 Extensive soil sealing in urbanizedareasBuilt surfaces in cities that influence the rainwater runoff have a dramaticimpact on the water cycle (fig. 20). In the table below, we see15 Cloudiness is another important aspect of a biologically well-working small watercycle. The role of clouds, besides inducing rain, is in the absorption and reflectanceof the global sun radiation. Through clouds, the incoming solar radiation isrestrained and hence the earth’s surface heats up less. In urban environments,poor on water bodies and vegetation, the local evaporation of water, and hencealso the creation of clouds in the adjacent atmosphere, is limited. More solarradiation permeates through the atmosphere and heats the earth’s surface up,rising the urban temperature.Fig. 19 The impact of the transformation ofland on the destruction of small water cycles.Rising radiant air flows pushes clouds to coolerenvironments, where the moisturing and thuscooling precipitation falls on earth. (Kravčík etal. 2007, p. 58)2 Literature review: The impact of built structures on climate, energy flow and the water cycle19
the values of water balance of various surfaces. This gives us indirectlythe information about the warming of the adjacent environment. Byvaporization of 1 kg of water at a temperature of 25°C, 2,243.7 kJ ofheat available from solar radiation are consumed (Kravčík et al. 2007,p. 25). On paved areas, where water runs off the surface or infiltratesdeep into the ground, this amount of radiation will be returned into theatmosphere in form of sensible heat. Thus, the lower the evapotranspiration,the higher the heating up of the surface as well as of theadjacent atmospheric layer (see the runoff values in Table 2):a.Table 2. Water balance of variously-used surfaces in mm. 1.1.2001-31.12.2004, TU Wilmersdorf, Berlin. (SenStadt Berlin and TU Berlin, p. 12)intosewageb.Fig. 20 Hydrologic flows in natural environment(a) and changes in hydrologic flows inurbanized catchments with increasing impervioussurface cover (b) and with widely pursuedinfiltration (c) (Göbel et al. 2004; adjusted),showing that mere infiltration provides highgroundwater recharge but has a dramatic effecton the decrease of evaporation rates.c.The aim in urban design should be to lower the runoff values tothe possible minimum and to infiltrate and particularly evaporate(fig. 20a) rainwater on site or as close to the site as possible – bycreating oveground, opened rainwater catchment basins and byenhancing vegetated areas around and on buildings that use therainwater for evapotranspiration and thus achieve energetic balance thatresembles the balance in rural areas (fig. 21).Another of the negative urbanization aspects observed in cities is themodification of natural water streams and ponds – filling in, enclosure(paving-over) or placing in culverts –, drainaging of the wetland surfaceand thus dramatically reducing the evaporative surface of opened waterbodies and adjacent riparian areas (Paul and Meyer in Marzluff et al.,2008, p. 211). The notion thus should be to re-open and restore the naturalstream channels in order to alleviate the urban temperatures. Themore opened water bodies and the greener the city, the higher latentheat partitioning and thus less sensible heat outflow, lowerheat storage and lower UHI effect (Emmanuel 2005, p. 124).Kravčík et al. (2007) warn that the drying of the continents, significantlyaugmented due to urbanization, is receiving very little public or scientificattention. The researchers insist that the water balance at all20Climate Sensitive <strong>Urban</strong> <strong>Design</strong> in Moderate Climate Zone: Responding to Future Heat Waves. Case Study Berlin Heidestrasse/Europacity
Page 1 and 2: Master’s Thesis in Urban Design:C
Page 3 and 4: ContentsAcknowledgements 5Abstract
Page 5 and 6: 4Climate Sensitive Urban Design in
Page 7 and 8: Abstract Deutsch/GermanAusgehend vo
Page 9 and 10: 8Climate Sensitive Urban Design in
Page 11 and 12: ing population 5 ) - more than a ha
Page 13 and 14: as the immense climatic effects of
Page 15 and 16: • Urban geometry: Tall buildings
Page 17 and 18: -°CFig. 11 Photographs of thin veg
Page 19: Fig. 14 Photograph of the square an
Page 23 and 24: size, lower than in cities of North
Page 25 and 26: wave radiation towards the sky. In
Page 27 and 28: Impact of the street orientation on
Page 29 and 30: Emergingof fresh andcold air100-200
Page 31 and 32: a. b.On the other hand, a concave w
Page 33 and 34: a.b.-°C-°C50-300 m-°CNot only te
Page 35 and 36: 2.5 Literature review: Lessons lear
Page 37 and 38: 3 Climate-Sensitive Urban Design(CS
Page 39 and 40: ought in the section 3.4, are mainl
Page 41 and 42: 3.2 Proposed CSUD GuidelinesThe set
Page 43 and 44: effect of a water body reaches into
Page 45 and 46: the street);c. Option b) + some of
Page 47 and 48: • Reduce quantity of lanes, where
Page 49 and 50: 3.3 Examples of CSUD in built urban
Page 51 and 52: 3.4 Climate-Sensitive Urban Design
Page 53 and 54: a.The proposal features a number of
Page 55 and 56: Action category ‘Ventilation’Ve
Page 57 and 58: Fig. 91/P18 West-East (W-E) Section
Page 59 and 60: 4 ConclusionsBased on the need to a
Page 61 and 62: Complementing recommendations regar
Page 63 and 64: GlossaryAdiabatic coolingAlbedoAmbi
Page 65 and 66: Mitigation “Measures taken to red
Page 67 and 68: SourcesBibliographyAgenda 21, onlin
Page 69 and 70: Matzarakis, A. (2001): “Die therm
Page 71 and 72:
The Physical Environment, online:
Page 73 and 74:
Fig. 25 The ‘sky view factor’ .
Page 75 and 76:
Fig. 93Fig. 94Proposed street and c
Page 77 and 78:
Appendices76Climate Sensitive Urban
Page 79 and 80:
Type of landuseDirect impact and ef
Page 81 and 82:
Appendix 2 City of Toronto’s Stud
Page 83 and 84:
(BAF - Biotope Area Factor continue
Page 85 and 86:
The building of the Institute of Ph
Page 87 and 88:
Castello development, seen from Lan
Page 89 and 90:
Bo01 seen from the 56th floor of th
Page 91 and 92:
(Bo01, Malmöcontinued)Water is the
Page 93 and 94:
Appendix 9 Posters Climate-Sensitiv
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Thesis document - Jana Milosovicova - Urban Design English

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