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Estimating the urban radiation heat flux distribution and the reduction effect of building and tree shade

건물과 수목의 그림자에 의한 도시의 열 분포 산정 및 저감효과 연구

  • Park, Chae-Yeon (Interdisciplinary Program in Landscape Architecture, Seoul National University) ;
  • Lee, Dong-Kun (Department of Landscape Architecture and Rural system Engineering, Seoul National University) ;
  • Yoon, June-Ha (Department of Landscape Architecture and Rural system Engineering, Seoul National University)
  • 박채연 (서울대학교 협동과정조경학) ;
  • 이동근 (서울대학교 조경.지역시스템 공학부) ;
  • 윤준하 (서울대학교 조경.지역시스템 공학부)
  • Received : 2018.09.28
  • Accepted : 2018.12.17
  • Published : 2018.12.31

Abstract

Mapping radiation heat flux of urban area is essential for urban design and landscape planning. Because controlling urban geometry and generating green space are important urban design strategies for reducing urban heat, urban planner and designer need to recognize the micro urban heat distribution for adequate urban planning. This study suggests a new methodology for mapping urban radiation heat flux in a micro scale considering buildings and trees' shade. For doing that, firstly, we calculate net radiation for each urban surfaces (building, road (not shaded, building shaded, tree shaded), ground (not shaded, building shaded, tree shaded), tree (not shaded, building shaded)). Then, by multiplying the area ratio of surfaces to the net radiation, we can obtain the radiation heat flux in micro-scale. The estimated net radiation results were found to be robust with a $R^2$ of 90%, which indicates a strong explanatory power of the model. The radiation heat flux map for 12h $17^{th}$ August explains that areas under the building and tree have lower net radiation heat flux, indicating that shading is a good strategy for reducing incident radiation. This method can be used for developing thermal friendly urban plan.

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Figure 1. Research Process and the model flow(1-2-3).

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Figure 2. Model geometry for estimating net radiation of urban surfaces.

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Figure 3. Urban surfaces types.

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Figure 4. Projection coordinate for calculating shade coordinates of tree and building.

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Figure 5. Field measurement sites.

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Figure 6. Comparison of model results (x axis) and measured net radiation fluxes. (y axis).

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Figure 7. Pilot site map and urban surfaces map.

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Figure 8. Net radiation map for 12:00 17th August.

Table 1. Input data for calculating net radiation.

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Table 3. The characteristics and net radiation of 4 locations (the locations are defined in Figure 8)

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Acknowledgement

Supported by : 국토교통과학기술진흥원

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