Cool Roofs for UHI COUNTERMEASURE: a Green Building added value.

Abstract

APEC WORKSHOP ON THE IMPLEMENTATION OF GREEN BUILDING CONCEPTS AND POLICIES IN EMERGING COUNTRIES

Full text

UHI COUNTERMEASURE
Cool Roofs for
a Green Building added value
Universitas Pendidikan Indonesia (UPI) –Project Manager of Cool Roofs Indonesia
Deliver to: “GR -APEC WORKSHOP ON THE IMPLEMENTATION OF GREEN BUILDING
CONCEPTS AND POLICIES IN EMERGING COUNTRIES”

Three main things happen when solar radiation hits
the surface of the roof material
•Absorption :Some degree of heat is
absorbed by the surface and transferred to
the material (partially absorbed).
•Solar Reflectance :Reflecting roof
some of the sun's energy. Materials with a higher
solar reflectance allow less heat to be transferred
to the environment.
•Thermal Emittance :Roof emit some of the
absorbed heat back into the atmosphere. Materials
with higher thermal emissivity also allow less
heat to be transferred to the environment.
HEAT TRANSFER
from solar radiation

Materials with low albedo values
(small u-values) heat arrives, partially
reflected (short wave) partially absorbed in
the material and only released heat at night
resulted in Urban Heat Island
URBAN SURFACE
materials

Heat trapped on surface material -due to the density of the building, usually on the roof and ground
coverage. Material properties in cities are important, they must have a high u-value high albedo 
able to reflect solar radiation materials with high SRI (solar reflectance index) values
HEAT TRAPPED
on surface material

Solar reflectance index (SRI) is an indicator
of the surface temperature of amaterial
under solar radiation
The SRI value of a material depends on its
ability to:
1. Reflecting solar radiation
2. Emits heat from the sun
A perfect black body has an emissivity
equal to 1 (ε=1). The more reflective an
object is, then the object has an emissivity
close to 0
The heat transfer mechanism affecting the surface
temperature under solar radiation
What is SRI???

MATERIAL APPLICATION

Cool roofs are coating (generally on roofs and
can be used on walls) that reflect the solar
radiation so that reduce the temperature
difference. This is important for buildings without
artificial cooling (AC) in hot humid tropical
climates where daily maximum temperatures are
above 30℃.
What is COOL ROOFS?

How
COOL ROOFS
works?

COOL WALL
Experiment

Indonesia lies in hot and humid climate zone, with an
average daily sun duration of 10 -12 hours, the need
for materials that have a high SRI (solar reflectance
index) is a must.
Cool roofs or cool walls can be one of recommended
coating for surface material to improve SRI
Reflective paint is proven as one of UHI
COUNTERMEASURE in urban areas with high diurnal
temperatures
CLOSING REMARK

TERIMA KASIH