Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
1
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Urban Heat Island 城市熱島效應
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
City changes the energy balance of the local climate
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
City changes the energy balance of the local climate
On the whole there is a positive energy balance in the city
2
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
http://www.albertasbestroof.com/images/stories/green-roofing/heat-island.jpgC
What is urban heat island? 什麼是城市熱島效應?
An urban heat island is the name given to describe the characteristic warmth of boththe atmosphere and surfaces in cities (urban areas) compared to their (non-urbanized) surroundings.
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Rural Urban
Q*
QH
QE
QG
RSL
DayQ*
QH
QEΔQSQF
Rural Urban
Q*QH QE
QG
RSL
Night
Q*QH QE ΔQSQF
Oke, Unpubl.
Canyon (UCL) Air Temp changes
The Main Cause of UHI Formation 城市熱島效應成因
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
• Reduced vegetation in urban areas
• Properties of urban materials
• Urban geometry
• Anthropogenic heat
The Main Cause of UHI Formation 城市熱島效應成因
3
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
A sky view in Hong Kong’s typical street canyon
UHI vs Sky View Factor (SVF)城市熱島效應與天空可見度的關係
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Correlation of ∆T and 150m radius neighbourhood average SVF value.
UHI vs Sky View Factor (SVF)城市熱島效應與天空可見度的關係
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Anthropogenic Heat 人工廢熱
Anthropogenic heat generated by energy consumed in the course of urban activities-especially by buildings, traffic, and industry plays an important role in urban climate. It is one of the main causes of the urban heat island effect, which is responsible for numerous severe problems in urban areas.
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Case Study in Singapore
Singapore
City Area: 710.2sq.KmPopulation: 4.9 millionsLocation: CostalTopographical: flat
Climate: Tropicalsummer: warmwinter: warm
4
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Case Study in Singapore
(Wong, 2004)
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Case Study in Singapore
Two major strategies to reduce the UHI effect exist:
• Introduce more green areas into the built environment (Plants serve to filter carbon dioxide and other toxins)
• Involve choosing proper building materials. (using light-coloured roofing material or reflective coatings lowers indoor and surrounding temperatures.)
(Wong, 2004)
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Case Study in New York
New York, US
City Area: 141,299 sq.KmPopulation: 19.5 millionsLocation: CostalTopographical: flat
Climate: Sub-tropic summer: warm, humidwinter: mild
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Case Study in New York
Rosenzweig, C.E., & Soleki, W.D. 2006. Mitigation New York City's Heat Island with Urban Forestry, Living Roofs, and Light Surfaces, New York City Regional Heat Island Initiative, The New York State Energy Research and Development Authority, Albany, New York.
5
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Case Study in New York
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Stuttgart, Germany
City Area: 207.36 sq.KmPopulation: 0.59 millionsLocation: InlandTopographical: in a Valley
Climate: Temperate summer: warmwinter: mild
(Baumüller, et al., 1998)
Case Study in Stuttgart
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Case Study in Stuttgart
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Case Study in Stuttgart
6
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
City Area: 2,187.08 sq.KmPopulation: 12.57 millionsLocation: CoastalTopographical: Flat
Climate: Temperatesummer: warm and humidwinter: cold
End to End- From Tradition to the New Frontier
CUHK Interdisciplinary Architectural Postgraduate Workshop 2008
Case Study in Tokyo
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Case Study in Tokyo
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Case Study in Tokyo
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Case Study in Tokyo
Tokyo Wall
7
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Case Study in Tokyo
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
1952
2007
With fast urbanization, it brings about local climate changes in Hong Kong.
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Measuring Urban Heat Island - Some Studies in Hong Kong
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
The conceptual character of Hong Kong urban geometry and heat generating process, Modified after Emmanuel,1997
(Giridharan et al., 2005)
Hong Kong has high density urban context. The typical buildings in Hong Kong are high rise and the H/W ratio is narrow. Some wind-blocking buildings at the seafront block the wind penetration and reduce wind speed. This special urban context deteriorates the urban living condition and intensifies the Urban Heat Island .
Hong Kong
Thermal image (Winter night)(South China Morning Post, 11 March 2007)
Measuring Urban Heat Island - Some Studies in Hong Kong
8
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
ASTER scene-corrected image of Surface Temperature
(Nichol, 2005)
Local researchers carried out various studies to analysis UHI in Hong Kong.The methods they used include Remote Sensing Image, Historical Meteorological Data Analysis, Mobile Measurement Study and MicroMeteorological Measurement Study.
Hong Kong
Cooling Effectof urban park and vegetated slopes at night
Measuring Urban Heat Island - Some Studies in Hong Kong
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
The difference of Air Temperature between rural and urban in HK (HKO Report, 2008)
Local researchers carried out a serious studies to analysis UHI in Hong Kong.The methods they used include Remote Sensing Image, Historical Meteorological Data Analysis, Mobile Measurement Study and Micro Meteorological Measurement Study.
Hong Kong
0.80.71.41.81.41.00.70.60.50.50.40.30.4Average daily Tu-r
2.21.92.93.73.22.62.11.91.91.81.61.41.3Mean Tu-r at 6 am
2.82.53.64.43.83.22.72.52.52.32.11.92.0Daily mean Tu-r
11.59.111.011.510.37.96.54.54.94.75.66.88.9Daily
maximum Tu-r
211211109876543
WinterAutumnSummerSpring Y
Month
Tu-r
Measuring Urban Heat Island - Some Studies in Hong Kong
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Temperature distribution along the route on the afternoon of summer day
(Fung, 2004)
Local researchers carried out a serious studies to analysis UHI in Hong Kong.The methods they used include Remote Sensing Image, Historical Meteorological Data Analysis, Mobile Measurement Study and Micro Meteorological Measurement Study.
Hong Kong
The UHI values in different periods(Fung, 2004)
Hottest regions in HK: The Kowloon Peninsular & The northern part of Hong Kong Island
The maximum UHI values in summer occurred in the morning while in winter it occurred at night .
Measuring Urban Heat Island - Some Studies in Hong Kong
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
The Map of Air Temperature Distribution for Tsim Sha Tsui site in a summer afternoon
Local researchers carried out a serious studies to analysis UHI in Hong Kong.The methods they used include Remote Sensing Image, Historical Meteorological Data Analysis, Mobile Measurement Study and Micro Meteorological Measurement Study.
Hong Kong
Ta Difference is about 3 - 4 ºC from seaside to inner site
Measuring Urban Heat Island - Some Studies in Hong Kong
9
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
What are the Problems with the "Heat Island Effect?"
May be for our mom, there is no problem. She may use the heat for cooking!
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Then, what are real problems?
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
The Consequences of UHI
Hot climateCold climateImpact
UHI circulation, breezes, stability, turbulence, convergence, uplift, mixed layer depth, cloud, precipitation, relative humidity, dewfall, evaporation, fog, visibility, snow, ‘contamination’ of long-term temperature records
Meteorological impacts
Not applicablePositiveIce and snow
Probably neutral except diseasePositiveBiological activity
NegativeNegativeWater use
Both positive and negativeBoth positive and negativeAir pollution dispersion
NegativeNegativeAir pollution chemistry
Negative (summer)
Negative (all seasons)Positive (winter)Energy use
Negative (summer)Negative (all seasons)Positive (winter)Human comfort
& mortality
Socio-economic and health impacts
Impacts of urban heat island (UHI) in cold and hot climate urban environments(Oke, 2002)
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
The Main Impacts in Hong Kong
Human comfort & mortality
Energy Use
10
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Increase of Very Hot Days and Very Hot Nights due to intra-urban temperature rises of 3 degree C.
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Urban Climate
City location• climate• topography• rural surrounds
Weather• wind• cloud• stability
City form• fabric• structure• cover
City size• fetch distance• density of use
Time• day• season
City metabolism• energy/water use• waste emissions
Oke, 1980, unpubl.
How could people mitigate the UHI?
How to Control or Mitigate the "Heat Island Effect?"
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Possible Planning Measures Learned from the WorldObjectives
UHIThermal
Load
+
WindDynamic Potential
Material & Surface Level Intervention
Building Level Intervention
Urban & Planning Level Intervention
Macro Effect
Micro Effect
Short time
Long time
Planning Time Scale Spatial Scale
Albedo• Cool building-material &
pavement;• Cool roof & facade; • Water retention paving;
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;
Strategies Planning Actions
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Controls on UHI effects
(Mochida, 2007)
• Change albedo
• Increase vegetation
• Provide shading
• Improve ventilation
Cool roof coatings.(US. EPA, 2007)
11
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Controls on UHI effects
(Mochida, 2007)
• Change albedo
• Increase vegetation
• Provide shading
• Improve ventilation
The distribution of air temperature for the area of a large park and its surroundings in Montreal, Canada (Marsh, 1991)
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Controls on UHI effects
(Mochida, 2007)
• Change albedo
• Increase vegetation
• Provide shading
• Improve ventilation
Tree’s effect.(US EPA, 2007)
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Controls on UHI effects
(Mochida, 2007)
• Change albedo
• Increase vegetation
• Provide shading
• Improve ventilation
(Ng, 2006)
School of Architecture, The Chinese University of Hong KongWorkshop on Urban Climatic for Design and Planning 5 & 12 June 2010
Hong Kong
5嵗小孩的素描, “我的香港”。A sketch by a 5 years old, titled “my Hong Kong”.
將來的環境是怎樣的?What will be the environmental future of Hong Kong?
我們的子女將生活在怎樣的將來?What kind of Hong Kong our sons and daughters will live?
Thank you for listening