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

2

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

3

ContentsContents




(4) Conclusions

4

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.

5

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)

6

Half of the surface of Tokyo is covered with artificial materials. Characteristic of building surface materials effects on urban temperature.

7

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.

8

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.

9

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)

10

ContentsContents




(4) Conclusions

11

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

12

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

13

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)

15

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

16

ContentsContents




(4) Conclusions

17

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

18

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.

19

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.

20

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


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

22

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.

23

100

90

80

70

60

50

40

30

20

10

0


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


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

24

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.

25

(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.

26

ReferencesReferences (Referred papers in this presentation are numbered.)(Referred papers in this presentation are numbered.)

High Reflective PaintsHigh Reflective Paints1)1) Y. Kondo, Y. Nagasawa and M. Y. Kondo, Y. Nagasawa and M. IrimajiriIrimajiri: Reduction of Solar : Reduction of Solar

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

27


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

5) S. 5) S. WakamaWakama, M. , M. NishiokaNishioka and M. and M. NabeshimaNabeshima: Thermal : Thermal Environment on High Reflection Pavement Part 1, Environment on High Reflection Pavement Part 1, Experimental Study and Evaluation of Thermal Experimental Study and Evaluation of Thermal Environment, Annual Meeting of AIJ, Environment, p. 689Environment, Annual Meeting of AIJ, Environment, p. 689--690, Sep., 2003690, Sep., 2003

6) T. Fujimoto, T. Okada and Y. Kondo: Reduction of solar heat 6) T. Fujimoto, T. Okada and Y. Kondo: Reduction of solar heat gain by using reflective paints for building envelops, gain by using reflective paints for building envelops, Transaction of AIJ, Journal of Environ. Transaction of AIJ, Journal of Environ. EngngEngng. , NO.601, . , NO.601, p.35p.35--41, Mar., 200641, Mar., 2006

28

7) Y. Kondo and T. Ohki: A countermeasure to Heat Islands by 7) Y. Kondo and T. Ohki: A countermeasure to Heat Islands by Promoting Cool Roof, The JTCCM Journal, Vol. 42, p.6Promoting Cool Roof, The JTCCM Journal, Vol. 42, p.6--14, 14,


May, 2006 May, 2006 Roof GreeningRoof Greening8) A. 8) A. HoyanoHoyano, J. He, T. , J. He, T. HoriguchiHoriguchi and G. Wang: Experimental and G. Wang: Experimental

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

9) A. 9) A. HoyanoHoyano, K. , K. ShiraiShirai, N. , N. OtsukaOtsuka and K. and K. IwamuraIwamura: Indoor : Indoor Thermal Control of Rooftop LawnThermal Control of Rooftop Lawn--planting with Thin Soil planting with Thin Soil Layer on A Wooden Layer on A Wooden BuindingBuinding, Journal of Architectural , Journal of Architectural Planning and Environmental Engineering of AIJ, No. 527, Planning and Environmental Engineering of AIJ, No. 527, p.15p.15--20, Jan., 200020, Jan., 2000

29

10) S. Yoshida, K. 10) S. Yoshida, K. HarayamaHarayama, R. , R. OokaOoka and S. Murakami: and S. Murakami: Study on Contribution Ratio of Outdoor Climate Part 4, Study on Contribution Ratio of Outdoor Climate Part 4,


Numerical Study on Effect of Roof Green and Ground Green Numerical Study on Effect of Roof Green and Ground Green on Thermal Environment Using NCR01, Annual Meeting of on Thermal Environment Using NCR01, Annual Meeting of AIJ, Environment, p. 927AIJ, Environment, p. 927--928, Aug., 2002928, Aug., 2002O Ishihara, Q. Zhang and K. O Ishihara, Q. Zhang and K. ShimoyamaShimoyama: Experimental : Experimental Study on Thermal Characteristics and Water Performance of Study on Thermal Characteristics and Water Performance of Rooftop Lawn, Journal of Architectural Planning and Rooftop Lawn, Journal of Architectural Planning and Environmental Engineering of AIJ, NO.484 , p.17Environmental Engineering of AIJ, NO.484 , p.17--24 , 24 , Jun.1996Jun.1996D. D. YunYun and A. and A. HoyanoHoyano: Evaluation of : Evaluation of revegetationrevegetation of urban of urban area by numerical simulation of heat balance, Journal of area by numerical simulation of heat balance, Journal of Architectural Planning and Environmental Engineering of Architectural Planning and Environmental Engineering of AIJ, No.520, p.69AIJ, No.520, p.69--75, Jun, 199975, Jun, 1999

30


H. Kagawa, J. H. Kagawa, J. TanimotoTanimoto, T. Katayama and A. , T. Katayama and A. HagishimaHagishima: : Parameter identification of water transfer characteristics in thParameter identification of water transfer characteristics in the e soil, Analytical studies of the soil, Analytical studies of the hygrothermalhygrothermal characteristics in characteristics in the soil under lawn surface, Journal of Architectural Planning the soil under lawn surface, Journal of Architectural Planning and Environmental Engineering of AIJ, No.525, p.27and Environmental Engineering of AIJ, No.525, p.27--32, Nov, 32, Nov, 19991999S. Yoshida, S. Murakami, A. Mochida, R. S. Yoshida, S. Murakami, A. Mochida, R. OokaOoka, Y. , Y. TominagaTominagaand S. Kim: Influence of green area ratio on outdoor thermal and S. Kim: Influence of green area ratio on outdoor thermal environment with coupled simulation of convection, radiation environment with coupled simulation of convection, radiation and moisture transport, Journal of Architectural Planning and and moisture transport, Journal of Architectural Planning and Environmental Engineering of AIJ, No.529, p.77Environmental Engineering of AIJ, No.529, p.77--84, Mar, 200084, Mar, 2000

31

S. Yoon and Y. Ashie: Numerical simulation on the summer S. Yoon and Y. Ashie: Numerical simulation on the summer


thermal environmental alleviation effect by urban planting in a thermal environmental alleviation effect by urban planting in a coastal local city, Transaction of AIJ, Journal of Environ. coastal local city, Transaction of AIJ, Journal of Environ. EngngEngng. , NO.577, p.41. , NO.577, p.41--46, Mar., 200446, Mar., 2004T. SATO, S. Murakami, R. T. SATO, S. Murakami, R. OokaOoka, S. Yoshida, K. , S. Yoshida, K. HarayamaHarayama and and H. Kondo: Numerical study on effects of countermeasures for H. Kondo: Numerical study on effects of countermeasures for urban heat island in summer and winter, The characteristic of urban heat island in summer and winter, The characteristic of urban climate and effects of greening and high albedo surface, urban climate and effects of greening and high albedo surface, Transaction of AIJ, Journal of Environ. Transaction of AIJ, Journal of Environ. EngngEngng. , NO.577, p.55. , NO.577, p.55--62, Mar., 200462, Mar., 2004M. Ichinose, H. M. Ichinose, H. IshinoIshino, K. , K. KohriKohri and A. Nagata: Evaluation of and A. Nagata: Evaluation of rooftop greening as a method of heatrooftop greening as a method of heat--island reduction based on island reduction based on actual measurement, Transaction of AIJ, Journal of actual measurement, Transaction of AIJ, Journal of Environ.EngngEnviron.Engng. , NO.605, p.47. , NO.605, p.47--54, Jul.200654, Jul.2006

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OthersOthersY. Ashie, H. Li and S. Yoon: Analysis of exhaustion Y. Ashie, H. Li and S. Yoon: Analysis of exhaustion characteristics of anthropogenic exhaustion heat considering characteristics of anthropogenic exhaustion heat considering the differences of sensible and latent heat in Tokyo 23 wards, the differences of sensible and latent heat in Tokyo 23 wards, Transaction of the Society of Heating, AirTransaction of the Society of Heating, Air--Conditioning and Conditioning and Sanitary Engineers of Japan, No. 92, p.121Sanitary Engineers of Japan, No. 92, p.121--130, Jan., 2004130, Jan., 2004K. K. UmedaUmeda, H. , H. FukaoFukao, Y. , Y. NamikiNamiki, T. , T. UchiikeUchiike and K. Nagase: and K. Nagase: Experimental study on water retentive pavement using water Experimental study on water retentive pavement using water supply method by solar power generation, Transaction of AIJ, supply method by solar power generation, Transaction of AIJ, Journal of Journal of Environ.EngngEnviron.Engng. , NO.605 , p.71. , NO.605 , p.71--78, Jul.2006 78, Jul.2006

current state and future prospects of cool roof in japan5) s. wakama, m. nishioka and m. nabeshima:...

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