The document summarizes the present status of energy saving roof paints in Japan. It discusses the heat island phenomenon seen in major cities and how highly reflective cool roof paints work to reduce temperatures. Such paints selectively reflect infrared rays to keep roofs and rooms cooler. Japan has standardized testing and certification of solar reflective paints through a new JIS standard. A three-year demonstration of cool roofs in Thailand showed indoor temperature reductions of 1-1.3°C and electricity savings for air conditioning of up to 14% compared to ordinary paints. With the 2020 Tokyo Olympics approaching, Japan is actively promoting cool roofs to help mitigate high summer temperatures.

1. 1
1
Present Status of Energy Saving Roof
Paints in Japan
Thursday, August 6th, 2015
Japan Paint Manufacturers
Association (JPMA)
Toshiya Takahashi
2
Contents
• Heat Island Phenomena in Big Cities
• Principles of Highly Reflective Coating
Materials (Cool Roof Paints)
• Standardization of High Solar Reflectant
Paints in Japan
• Review of Demonstration Experiment of Cool
roof in Thailand (3 years)
• Toward Tokyo Olympic games (2020)

2. 2
3
Rises of Average Temperature in
Japan ( Metrological Agency, Japan)
City
Average Rises per 100 years
（℃／100 years）
Annual January August
Sapporo +2.3 +3.0 +1.5
Sendai +2.3 +3.5 +0.6
Tokyo +3.0 +3.8 +2.6
Nagoya +2.6 +3.6 +1.9
Kyoto +2.5 +3.2 +2.3
Fukuoka +2.5 +1.9 +2.1
Ave. in Big Cities +2.5 +3.2 +1.8
Ave. in Small Cities +1.0 +1.0 +1.0
4
Distribution in Total Hours When Temperature is
above 30℃ in Summer (Tokyo Area)
(Ministry of Environment)

3. 3
5
Countermeasures for
Heat Island Phenomena
• Green Roof (Plants)
• High Solar Reflectant Paint
• Others
• Tokyo Metropolitan Government
• Cool Roof Subvention
– Green Roof
– High Solar Reflectant Paint
6
Contents
• Heat Island Phenomena in Big Cities
• Principles of Highly Reflective Coating
Materials (Cool Roof Paints)
• Standardization of High Solar Reflectant
Paints in Japan
• Review of Demonstration Experiment of Cool
roof in Thailand (3 years)
• Toward Tokyo Olympic games (2020)

4. 4
Mechanism of Energy Saving
Reflect infrared Ray and Heat by Painting
Systems Coated on Outer Surface
Convection
Reflect
Heat
Thermal
Conduction
60～70℃
40～50℃
Outside Temperature
33℃
Outside Temperature
30℃
Room Temp.
at 28℃
Reflect
Heat
Energy
Saving
House without Solar
Reflective Paints
House with Solar
Reflective Paints
50～60℃
40～50℃
Back side of
the Roof
50℃ 40℃
SmallHighRadiation
Solar Reflective Paint
Heat Reflective Barrier
7
8
Out Door
Ordinary Paints
Coated
Material
(Galvanized
Plate or etc.) Room
inside
Temperature
inside rood shall
be warmed up
Temperature at room inside can be heated
up, since materials used in roof, wall etc.
are heated by infrared rays and the heat
can be transfered to internal spaces.
Infrared rays
Theory of Solar
Reflective Paints
Insolation contains infrared rays
which warm up building materials.
Paint films together with housing
materials absorb the heat from the
infrared rays and the heat can be
transferred to inside of the room.
Then the temperature room inside can
be warmed up. This warming up is
most intensively occured on the roof
or the housetop and is very dependent
on the color of the topcoat. The darker
color, the more heat can be transferred.
Paint Film Layer

5. 5
9
Selectively reflect infrared
rays on the surface of the
top coat
Out
Door
Room
inside
Infrared rays
Paint pigmented to be
more reflective
against Infrared rays
Solar Reflective Paints
Substrate
Solar
Reflective
Coating
Reflect the penetrated
infrared rays on the
surface of the intermediate
white coat
Out
Door
Room
inside
Infrared rays
Infrared Rays
penetrates into a top
coat can be reflected on
the surface of the
intermediate coat.
Substrate
Intermediate white/Metallic coat
Strategy to reflect the infrared rays
Draw-A
The infrared rays are to be reflected on the surface of the top coat thanks to the top coat formulated with more
Infrared-reflective pigments.
Draw-B
Even if there would be some infrared rays which are not reflected on the surface of the top coat and penetrate into
the top coat, such penetrated infrared rays are to be reflected on the surface of the intermediate coat.
Draw- A Draw-B
10
Reflectance spectrum by spectral photometer
（nm）
γray, X ray ← → Microwave, Radio
ReflectionCoefficient(%)
Reflectance spectrum detected by spectral photometer on
a gray color topcoat Wave length (nm)
Giving more impact
on warming up
A solar reflective paint
An ordinary paint
This figure shows that
a solar reflective paint
can selectively reflect
infrared rays very
efficiently.

6. 6
11
Contents
• Heat Island Phenomena in Big Cities
• Principles of Highly Reflective Coating
Materials (Cool Roof Paints)
• Standardization of High Solar Reflectant
Paints in Japan
• Review of Demonstration Experiment of Cool
roof in Thailand (3 years)
• Toward Tokyo Olympic games (2020)
5
12

7. 7
13
JIS K 5602 Determination of Reflectance of
Solar Radiation by Paint Film
Reflectance of Solar
Radiation
Eλ: Standard Sunlight Spectrum
Eλ・Δλ：Weight Coefficient (Wavelength 300～2500nm)
for JIS K 5675(780~2500nm)
ρλ: Reflectance Percentage
Eλ and Δλ : standardized by ISO 9845-1 (Solar energy−Reference
solar spectral irradiance at the ground at different
receiving conditions−Part 1: Direct normal and
hemispherical solar irradiance for air mass 1.5)
=
JIS and policy
support
Standard certification zone

8. 8
Solar Reflectant Paint
• Low Value (L* ≦40.0)
– Solar reflectance is higher than 40%.
• Middle Value （40.0＜L* ＜80.0）
– Solar reflectance is higher than its value
(Brightness).
• High Value （L*≧80.0）
– Solar reflectance is higher than 80%.
• Solar Reflectance Retention after 2 years
outdoor exposure
– Solar Reflectance Retention Percentage is
higher than 80%.
JIS K5675 major requirements
Durability grade
１ ２ ３ Low gloss（70>）
Artificial durability test 2500 hrs 1200 hrs 600 hrs
Initial Gloss % 80< 70< ー
Outdoor exposure 2 years
Gloss retention % 60< 40< 30< ー
Initial Solar reflectance % Defined as figure (former slide)
Solar reflectance
retention after 2 yeaｒs %
80<
Other quality
requirements
Same as JIS K 5658(High
durability paint for outdoor
archiecture)
Remark Solar reflectance(300~2800nm) value should be indicated

9. 9
17
Further Standardization and
Green Roof material certification
• Development and Standardization of Solar Heat Gain
Coefficient Measurement for Energy Saving Paint （In 2017 ,
new JIS will be published)
(On-Going Project)
Target completion year of the certification
system(2019)
Solar heat gain coefficient
measuring instrument
Heat reflux rate←Lower Higher →
RatingLabelview
(a) Substrate( Metal, slate, insulated roof products, etc.)
(b) Paint Film (f) Air flow sensor
(c) Surface Temp. sensor (g) Air blower
(d) High transparency glass (h） Out door Temp, sensor
(e) Sunlight analogous light source (i ) Heat flow Sensor
(j ) Heat sink
(h)
(i )
(j)
Green Roof material Certification
(Label Image)
18
Contents
• Heat Island Phenomena in Big Cities
• Principles of Highly Reflective Coating
Materials (Cool Roof Paints)
• Standardization of High Solar Reflectant
Paints in Japan
• Review of Demonstration Experiment of Cool
roof in Thailand (3 years)
• Toward Tokyo Olympic games (2020)

10. 10
Copyright 2015 by JPMA. All rights ｒｅserved.
Geographical Position of Thailand and Japan
19
Bangkok Tokyo
Lati 13°5′ N 35°41′ N
Iong 100°29′ E 139°44′ E
０°
1） Coating systems
20
Syste
m No.
Type
Brightness
(white /Black)
and
Hue
Additional
function
Solar Ref
(Total range/
near IR range)
ΔＳＲ （nＩＲ）
(Popular-
Cool roof)
Luminous Value
1 General paint Ｎ－８ Near White 54.7/ 49
34
80
2 Cool Roof paint Ｎ－８ Near White 70.3 / 83 80
3 Generalpaint Ｎ－６ Gray 26.0 / 22
53
59
4 Cool Roof paint Ｎ－６ Gray 50.9/ 75 59
5 General paint Ｎ－4 Brown 6.9/ 7
49
21
6 Cool Roof paint Ｎ－4 Brown 29.6/ 56 23
7 General paint Ｎ－６ Gray/Primer
Heat- insulating
Primer 300mμ 26.0 / 22
53
60
8 Cool Roof paint Ｎ－６ Gray/Primer
Heat- insulating
Primer 300mμ 50.6/ 75 59

11. 11
Copyright 2015 by JPMA. All rights ｒｅserved.
2. Layout of the Experimental Houses and Boxes
N
8
N
6
●ヨドハウス各部屋とサーバー室間の土工部の溝(穴)掘り
① ③ ⑤
⑦ サーバー室 ⑧
② ④ ⑥
N
S
EW
扉窓
エアコン
エアコン
室外機
簡易BOX
Ordinary
paint
Solar
reflective
paint
Brown
22
A Proving Test on Solar Reflective Paints in Thailand
A test house
Painting system adapted in this test
• System No. 2, 4, 6 & 8 : A series of Solar Reflective
Paints were applied as top coats.
• System No. 1, 3, 5 & 7 : A series of Ordinary Paints
were applied as top coats.
• System No.7 & 8 : A heat insulation paint was
applied as a intermediate.
Overview of the test site
in Bangkok, Thailand
A test box

12. 12
Copyright 2015 by JPMA. All rights ｒｅserved.
23
2.5 Sensors’positions in the test
house and the test Box
Copyright 2015 by JPMA. All rights ｒｅserved.
Indoor temperature of Test house No.5
General paint Cool Roof paint Difference
Ｎ８ 21.0 ℃ 19.7 ℃ 1.3 ℃
Ｎ６ 21.0 ℃ 19.8 ℃ 1.2 ℃
Brown 21.5 ℃ 20.5 ℃ 1.0 ℃
In 2014 (January to December) Test House indoor temperature
4.5 Summary of Electricity consumption
due to Air conditioner
Temperature difference
Air conditioner
exit temperature
air conditioner
intake temperature
Indoor temperature
Test HouseNo.5 Room: Ordinary
Brown

13. 13
Copyright 2015 by JPMA. All rights ｒｅserved.
Air conditioner power consumption reduction ratio ：
  100
paintGeneral
paintRoofCool-paintGeneral
ratio(%)reduction 
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
MAX. 12.0% 10.9% 5.5% 13.6% 13.7% 11.4% 8.9% 10.9% 9.4% 14.0% 9.2% 9.8%
Ave. 8.2% 6.2% 3.4% 9.8% 11.5% 6.7% 6.4% 7.4% 7.4% 8.2% 6.3% 6.1%
表9：Air conditioner consumption reduction ratio of month
5.5 Summary of Electricity consumption
due to Air conditioner
Brown Roof
26
Contents
• Heat Island Phenomena in Big Cities
• Principles of Highly Reflective Coating
Materials (Cool Roof Paints)
• Standardization of High Solar Reflectant
Paints in Japan
• Review of Demonstration Experiment of Cool
roof in Thailand (3 years)
• Toward Tokyo Olympic games (2020)

14. 14
Mid-summer Tokyo Olympic games dramatically
Accelerates Cool roof policy in Japan
• METI, MILT and Tokyo Metropolitan Government, are
pushing cool roof policy actively.
• Solar Heat Gain Coefficient Measurement for Energy
Saving Paint and roof materials will be an essential
standard to promote its policy.
• Overcoming the frame of vertically divided
administration, each ministry has been promoted a
number of demonstration projects in collaboration.
• I will show you some examples of Cool roof-related
projects.
27
Embodiments in building and pavements
28
Parking area
Food processing plants
Shopping mall rooftop Hotel foot path
Pedestrian precinct
Painting of all the pavement of the park

15. 15
29
Thank you for your attention.