In construction, the R - value is the measurement of a material's capacity to resist heat flow from one side to the other. R - value measures the effectiveness of insulation and a higher number represents more effective insulation.
S.R.I (Solar Reflective Index) tiles are to be fixed in terrace after maintaining R- value in terrace. ECBC - 2017 (Energy Conservation Building Code - 2017) specifies R value for different climate zones. R value cannot be achieved by using normal concrete materials like cement, crusher jelly / chips and M sand etc.
8 inch Concrete Masonry unit (CMU) is having R value of 1.11.
1 inch Polyurethane Foam (Foamed at site) is having R value of 6.25.
1 inch Vermiculite is having R value of 2.0.
Roof slab is mainly composed of cement and crusher jelly. Screed concrete is required to maintain gradient over roof slab. If we use cement and crusher jelly / chips for gradient, R value specified by ECBC can never be achieved. S.R.I tile must be fixed only on well insulated terrace. ECBC suggests R value of 3.1 for roof (ECBC 2017 section 4.3.1).
If we use vermiculite concrete, R value can be achieved. Generally an average of 2 inch screed is required for smooth flow of rain water. R - value of 3.0 can be easily achieved in vermiculite concrete.. Alternately hydrated lime concrete also can be used. It needs proper sampling with locally available materials and test R value.
After R value exercises and screed work, fix S.R.I tiles (ECBC 2017 section 4.3.1.1).
R - value in terrace + S.R.I Tiles = Sustainable Cool Roof. (Green Pro certification for R value tested Screed / Mortar and S.R.I Tiles). This is to comply with ECBC 2017 norms under the sections of 4.3.1 and 4.3.1.1 respectively.
ABC is the first brand in ceramic cool tile and subsequently Cool Roof. Now a days, there are numerous suppliers claiming cool roof. Unless cool tile is fixed as per ECBC norms, no one can claim as I have fixed Cool Roof.
Fixing cool tile alone does not guarantee for cool roof. It is only superficial knowledge or half baked experience unless and until ECBC norm is fully grasped and followed. Cool tile or S.R.I Tile is one of the component in terrace. There are many other factors for a sustainable terrace.
ABC S.R.I Cool Tiles has taken initiative to get Green Pro certification for R - value products(Screed and Mortar). S.R.I Tiles already certified for Green Pro.
Source : https://www.abceramic.in/blog-what-are-r-values-and-how-r-value-is-related-to-cool-roof--21.php