1. Innovative roof cool roofs by T.Maniammai & T.M.Supraja

2. What is a cool roof ? A cool roof reflects the sun’s heat and emits absorbed radiation back into the atmosphere.

3. Properties of cool roof
high solar reflectivity- degree to which a roof reflects heat
high emissivity- roof's ability to give off its absorbed heat.

4. Types of cool roof
Inherently cool roof
Coated roofs
Green roofs

5. Inherently cool roofs
Roofs made of materials that are inherently cool.
Coatings are not provided
Metal roofs and asphalt shingles are commonly used

6. Asphalt shingles Similar to rolled asphalt roofs
roofing granules pressed into the shingle while it is hot (and soft)
The roofing
granules are
1 millimeter-sized
stones
(e.g., of crushed granite)

7. Roofing tiles
Tile roofs often have enhanced air circulation compared to other roofing types
Roofing tiles can be ceramic or fabricated from cement concrete. Some of the lighter types use fibers (e.g., cellulose) added for strength.

8. Metal roofs
Aluminum and steel may have a solar reflectance of 60 % and low emittence
The reflectance and emittance of metals are very sensitive to the smoothness
Even a thin white coating "hides" the low emittance of the metal

9. “White” is new green White paint serve good Highly reflective coating
Economical
Easily available
Paint is easy to apply
and dries soon

10. White elastomeric solar coating
An elastomer is a polymer with the property of viscoelasticity
Soft and are amorphous polymers existing above their glass transition temperature
Examples: acrylic polymers, polyurethane

11. THE BETTER ELASTOMER POLYURETHANE……… Solvent based.
strong tensile strength.
exhibit greater adhesion.
often used with metal roofs.
At high solids levels meet VOC regulations.

12. WHY ACRYLIC IS NOT PREFERED
Not prefered for cold climate as it gets affected when comes into contact with water
The ASTM D-6083 standard defines the performance properties for an acrylic coating.
Should be used only when there is proper drainage.

13. Coating is better
The solar reflectence of asphalt is only 20 % whereas the elastomeric coating has a solar reflectance of 80% and hence it is prefered
Asphalt is prefered for sloped roofs

14. Selection of coating
Depends on substrate
Age of roof
Climate

15. Surface preparation Remove dirt and scum Pressure washing
Scratching the surface
Application of primer
In metal roofs if there is corrosion use inhibitors
Coating acts as sealant for water leaks

16. Substrate with coating

17. How to apply ?

18. Failure patterns

19. Prevention of failure
Weaknesses of the original roof system must be corrected
roof should be made watertight
Weather conditions during the project installation must be monitored.
The roof should drain properly
Roof should be maintained and coating should be replaced periodically

20. Green roofs Making the roof green……….
Improved air quality as the plants absorb and convert carbon dioxide to oxygen
Long lifespan - some green roofs in Europe have lasted more than 40 years
Excellent insulation
Cooled surrounding environment
increases the area of habitat for wildlife such as birds and insects

21. Green roofs

22. A special note on TiO2 provides opacity increase solar reflectance
reduce surface temperatures
absorbs UV radiation

23. SELF CLEANING
Photoactive TiO2 particles in the binder promote free radical attack at the surface of the system Inorganic dust remains but “glue” can be destroyed therefore reducing the adhesion force between the particles and the surface .When it rains these particles are washed away rejuvenating the surface.

24. Vermiculite
Vermiculite is a natural mineral that expands with the application of heat. The expansion process is called exfoliation .
It has low thermal conductivity ,light weight, not flammable.
Applied as weathering course by mixing with equal weight of cement and sufficient water

25. Policy and Code Bodies
ECBC--‐ ‐ Bureau of Energy Efficiency (BEE)
LEED --‐ Indian Green Building Council (IGBC)
GRIHA --‐ The Energy and Research Institute (TERI/ MNRE)
Ministry of Environment and Forests, Government of India--‐ MoEF –
Bureau of Indian Standards (BIS)
The Energy Conservation Building Code (ECBC)

26. Benefits of cool roof Reduce building heat-gain,
as a white or reflective roof
typically increases only 5–14 °C
above ambient temperature.
Create 15–30%  savings on
summertime air conditioning
expenditures.
Enhance the life expectancy of building’s cooling equipment.

27. Benefits Improve thermal efficiency of the roof insulation
Reduce the demand for electric power
Reduces greenhouse gas emissions.
If all urban, flat roofs worldwide were whitened, the reduction in carbon emissions would be 24 Gigatonnes, or equivalent to taking 300 million cars off the road for 20 years.