Current State and Future Prospects of Cool Roof in Japan5) S. Wakama, M. Nishioka and M. Nabeshima:...
Transcript of Current State and Future Prospects of Cool Roof in Japan5) S. Wakama, M. Nishioka and M. Nabeshima:...
1SANTORINI Island
Yasushi Kondo, Musashi Inst. of Tech.Yasushi Kondo, Musashi Inst. of Tech.
Current State and Future Prospects of Current State and Future Prospects of Cool Roof in JapanCool Roof in Japan
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ContentsContents
(1) Activities of Cool Roof Committee in AIJ
(2) Private Benefit and Public Benefit of Cool Roof
(3) Cool Roof Promote Project
(4) Conclusions
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ContentsContents
(1) Activities of Cool Roof Committee in AIJ
(2) Private Benefit and Public Benefit of Cool Roof
(3) Cool Roof Promote Project
(4) Conclusions
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Cool Roof Committee of AIJAIJ: Architectural Institute of Japan
Members: Y. Kondo, Musashi Inst. of Tech.Y. Ashie, Building Research Inst.H. Shibaike, Kyoto Inst. of Tech.H. Takebayashi, Kobe Univ.H. Namiki, Taisei Co. K. Narita, Nippon Inst. of Tech.H. Narimi, Osaka Univ.M. Nishioka, Osaka City Univ.S. Hashida, Meiji Univ.A. Hoyano, Tokyo Inst. of Tech.Y. Matsuo, Meiji Univ. I. Misaka, Takenaka Co.A. Mochida, Tohoku Univ.M. Moriyama, Kobe Univ.
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Main Factors on Heat Island PhenomenaMain Factors on Heat Island Phenomena
Exhaust heat used in buildings
24%
Exhaust heat used in factories
etc. 7%
Exhaust heat from vehicles 21%
Heat from DHC plants
1%
Convection from building surfaces etc.
(Increase rate compared to natural
surfaces)47%
Sensible Heat in Urban Area(Daily Average in Tokyo, Ministry of the Environment)
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Half of the surface of Tokyo is covered with artificial materials. Characteristic of building surface materials effects on urban temperature.
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Heat Balance of Roof
ReflectionEvaporation
Convection
Conduction Roof
Absorption
Long WaveRadiation
(Downward)Short WaveRadiation
Long WaveRadiation(Upward)
The surface temperature of a roof can be decreased by controlling several factors affecting the heat balance of a roof.
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The cool roof committee of AIJ discussed
latent heat as well as sensible heat.
Therefore the roof planting and water
retentive materials are also studied
in the committee.
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Research Group Research Subject Reference
Matsuo Lab. Meiji Univ. Reflective Paint Y. Nishimura et al. (2004)
Ashie Lab. BRI Water Retentive Material
Moriyama Lab. Kobe Univ. Various Cool Roofs S. Nogami et al. (2004)
Hoyano Lab. Tokyo Inst. of Tech.
Rooftop Lawn-Planting A. Hoyano et al. (1994)A. Hoyano et al. (2004)
Nishioka Lab. Osaka City Univ.
Reflective Pavement S. Wakama et al. (2003)
Mochida Lab. Tohoku Univ.
CFD on Green Area Ratio
S. Yoshida et al. (2003)
Murakami Lab. Tokyo Univ. CFD on Roof Planting S. Yoshida et al. (2002)
Tokyo Metropolitan Gov. and Japan Testing Center for Construction Materials
Roof Planting andReflective Paint
T. Fujimoto et al. (2006)
Kondo Lab. Musashi Inst. of Tech.
Reflective Paint Y. Kondo et al. (2000) (2006)
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ContentsContents
(1) Activities of Cool Roof Committee in AIJ
(2) Private Benefit and Public Benefit of Cool Roof
(3) Cool Roof Promote Project
(4) Conclusions
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Cool roof reduce energy consumption for cooling buildings.
Cool roof reduce sensible heat flux from roofs to the atmosphere.=>Public Benefit
=>Private Benefit
Solar radiationSolar radiation
Cool Roof
Cooling load:Cooling load:
HighHigh
Reflection:LowReflection:Low
Cooling load:Cooling load:
LowLow
Solar radiationSolar radiation
Reflection:HighReflection:High
General Roof
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Roof without insulationRoof without insulation(R= 0.51 m(R= 0.51 m22K/W)K/W)
Reduction:Large(Simulation results of summer condition in Tokyo)
Relationship Between Cool Roof and Cooling Load
Solar Reflective Solar Reflective
Coo
ling
load
(Inte
grat
ing
valu
e pe
r day
)[M
J/m
2da
y]
Coo
ling
load
(Inte
grat
ing
valu
e pe
r day
)[M
J/m
2da
y]
(R= 2.29 m(R= 2.29 m22K/W)K/W)
Reduction:Small
Well insulated roofWell insulated roof
When the roof is not well insulated, cooling load and/or indoor temperature can be decreased by increasing the rooftop reflectivity
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Relationship Between Cool Roof and Local Climate (Ref. 1)
Total AirTotal Air--conditioning Load (Heating Load + Cooling Load)conditioning Load (Heating Load + Cooling Load)
0
20
40
60
80
100
120
140
(2) House(2) House
[MJ/m2・year]
0
50
100
150
200
250
300
350
400Case1:General paintCase2:Cool paint on roofCase3:Cool paint on roof and wall
Asah
ikaw
a
[MJ/m2・year] Heating Load Cooling Load
(1) Warehouse(1) Warehouse
0
100
200
300
400
0
40
80
120
Heating Load Cooling Load
Case1:General paintCase2:Cool paint on roofCase3:Cool paint on roof and wall
Sapp
oro
Send
ai
Mat
sum
ot
Toky
o
Nag
oya
Osa
ka
Hiro
shim
a
Fuku
oka
Nah
a
Asah
ikaw
a
Sapp
oro
Send
ai
Mat
sum
ot
Toky
o
Nag
oya
Osa
ka
Hiro
shim
a
Fuku
oka
Nah
a
The total load can only be reduced in hot areas. The total load can only be reduced in hot areas. The effect of high reflective paint on the The effect of high reflective paint on the airair--conditioning load depends on the local climate.conditioning load depends on the local climate.
How much sensible heat from urban surfaces can be reduced ??
(a) Commercial area Shinjuku ward
(b) Residential area Setagaya ward
(c) Industrial area Shinagawa ward
Gross building
coverage ratio
A Decreased
sensible heat
BAnthropogenic
exhaustion heat(Ref. 11)
[MJ/m2 . day] [MJ/m2. day]3.70
Setagaya ward 30.0 0.79 1.62 48.7Shinagawa ward 29.2 0.77 3.86 19.9
0.95[%]36.0
A/B
[%]25.7Shinjuku ward
Decrease of Sensible Heat in applying Cool Roof (Ref. 7)
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Cool roof can reduce the cooling load of buildings with low insulation.
Cool roof is effective in decreasing urbanarea temperature in summer.
=> Private Benefit
=> Public Benefit
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ContentsContents
(1) Activities of Cool Roof Committee in AIJ
(2) Private Benefit and Public Benefit of Cool Roof
(3) Cool Roof Promote Project
(4) Conclusions
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Environment Bureau of Tokyo Metropolitan Government
Since April 2001 Tokyo Metropolitan Government has required greening rooftops and wall surfaces for new grounds and buildings that have a ground surface of over 1,000m² (250m² for public facilities).
54.5ha of rooftops have been greened as of January 1, 2005.
http://www2.kankyo.metro.tokyo.jp/kouhou/env/eng/index.html
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Cool Roof Promote Project started in 2005Cool Roof Promote Project started in 2005http://www2.kankyo.metro.tokyo.jp/heat/coolroof/coolroofpress.pdf
Committee to Promote Cool RoofCommittee to Promote Cool RoofMembers:
http://www.coolroof.jp/
Environment Bureau of Tokyo Metropolitan GovernmentSeveral Tokyo wards: Chiyoda ward, minato ward, shinjyuku ward etc.Japan Paint Manufactures AssociationCenter for environmental Information ScienceNPO Roof development research center
The building owners who apply rooftop greening or The building owners who apply rooftop greening or high reflective paint can get a grant from Ministry of high reflective paint can get a grant from Ministry of the Environment, if they meet the requirements.the Environment, if they meet the requirements.
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Many high reflective paint products are distributed in the Japan market.
However there is no authorized standard for performance of high reflective paints in Japan.
A standard or qualification system should be considered in Japan.
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Reflectance Spectra of Various Reflective Paint Products
(Ref. 6)
Product No. 12 Product No. 18
Measured Reflectance Spectra
100
90
80
70
60
50
40
30
20
10
0
分光反射率 (%)
2500200015001000500
波長 (nm)
No.12 白色 黒色 灰色
100
90
80
70
60
50
40
30
20
10
0
分光反射率 (%)
2500200015001000500
波長 (nm)
No.18 白色 黒色 灰色
Wave length [nm]
InfraredVisible
Wave length [nm]
InfraredVisible
Ref
lect
ivity
[%]
WhiteBlackGray
Ref
lect
ivity
[%]
WhiteBlackGray
500 1000 1500 2000 2500 500 1000 1500 2000 2500
0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
40
50
60
70
80
90
100
The performance of 21 reflective paints was examined.
21
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
No.1
No.2
No.3
No.4
No.5
No.6
No.7
No.8
No.9
No.10
No.11
No.12
No.13
No.14
No.15
No.16
No.17
No.18
No.19
No.20
No.21
標準試料
White Gray Black
40%40%
Sol
ar R
efle
ctan
ce [%
]100.0
80.0
60.0
40.0
20.0
0.0
Product No.
1 2 3 4 5 6 7 8 109 1111 12 1413 15 16
16
17 18 19 20 21
Gen
eral
Comparison of Solar Reflectance in Various Products
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Ageing of Reflective Paints by Exposure Testing
16 white paints 14 gray paints 14 black paints
Tokyo Metropolitan Gov., Japan Testing Center for Construction Materialsand Kondo Lab. Musashi Inst. of Tech.
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100
90
80
70
60
50
40
30
20
10
0
分光反射率 (%)
2500200015001000500
波長 (nm)
試験体⑬白色
曝露前 曝露後1 曝露後2 曝露後3 曝露後4
100
90
80
70
60
50
40
30
20
10
0
分光反射率 (%)
2500200015001000500
波長 (nm)
試験体⑬黒色
曝露 曝露 曝露 曝露 曝露
121days later 197 days later 342 days later 571 days laterNot exposed Wavelength [nm] Wavelength [nm]
Ref
lect
ivity
[%]
Ref
lect
ivity
[%]
500 1000 1500 2000 2500 500 1000 1500 2000 25000
10
20
30
40
50
60
70
80
90
100
0
10
20
30
40
50
60
70
80
90
100
Black (Product No.13)White (Product No.13)
Results of Ageing Test on Reflective Performance
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Solar Reflectance [%]
Visible Ray Reflectance [%]
Infrared Ray Reflectance [%]
Not exposed
571 days later
Not exposed
571 days later
85.2 50.4
6.95.8
Not exposed
571 days later
White 80.8 54.8 82.1 61.4
Black 40.4 30.7 71.2 51.5
Example (Product No.13)
When high reflective paint is applied, the ageing of performance should be considered.The recovery method of performance should be studied.
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(4) Conclusions(4) Conclusions
[1] The research studies on cool roof in Japan are shown.
[2] Private benefit and public benefit of cool roof are shown.
[3] An example of cool roof promote project is introduced. Some problems to promote the application of cool roof are discussed.
The designers and owners of building should recognize the private benefit of cool roof properly and apply it.
The policy maker should recognize the public benefit of cool roof properly and promote it.
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ReferencesReferences (Referred papers in this presentation are numbered.)(Referred papers in this presentation are numbered.)
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Heat Gain of Building, Urban Area and Vending Machines Heat Gain of Building, Urban Area and Vending Machines by High Reflective Paint, Transaction of the Society of by High Reflective Paint, Transaction of the Society of Heating, AirHeating, Air--Conditioning and Sanitary Engineers of Japan, Conditioning and Sanitary Engineers of Japan, No. 78, p.15No. 78, p.15--24, Jul., 200024, Jul., 2000
2) Y. Nishimura, Y. Matsuo, K. Miki and T. 2) Y. Nishimura, Y. Matsuo, K. Miki and T. MuraseMurase: On the : On the Effect of Infrared Reflective Paint to Reduce Solar Heat Effect of Infrared Reflective Paint to Reduce Solar Heat Gain Part 2, Annual Meeting of AIJ, Environment, p. 357Gain Part 2, Annual Meeting of AIJ, Environment, p. 357--358, Aug., 2004358, Aug., 2004
3) http://3) http://www.coolroof.jp/faq/index.htmlwww.coolroof.jp/faq/index.html
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4) S. 4) S. NogamiNogami, M. Moriyama, H. , M. Moriyama, H. TakebayashiTakebayashi et. al.: A Study of et. al.: A Study of Cool Roof (part1), Measurement of sensible heat flux by Cool Roof (part1), Measurement of sensible heat flux by means of the residue of heat budget, Annual Meeting of AIJ, means of the residue of heat budget, Annual Meeting of AIJ, Environment, p. 795Environment, p. 795--796, Aug., 2004796, Aug., 2004
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Study on Heat Budget for Foliage Layer of LawnStudy on Heat Budget for Foliage Layer of Lawn--planting. planting. Effect of Rooftop LawnEffect of Rooftop Lawn--planting on Thermal Environment planting on Thermal Environment Part 1, Journal of Architectural Planning and Part 1, Journal of Architectural Planning and Environmental Engineering of AIJ, No. 462, p.31Environmental Engineering of AIJ, No. 462, p.31--39, Aug., 39, Aug., 19941994
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