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Solar Reflective Index(SRI) becomes an important parameter while selecting a highly reflective roof coating which keeps roof cool, lowers the indoor temperature and reduce the cooling cost in a building
The solar reflectance index (SRI) is a measure of the constructed surface’s ability to reflect solar heat, as shown by a small temperature rise. Thermal emittance is the relative abilility of a roof to emit (release the heat back into atmosphere) heat that has been absorbed.It is defined so that a standard black surface (reflectance 0.05, emittance 0.90) is 0 and a standard white surface (reflectance 0.80, emittance 0.90) is 100. It depends on something called Albedo, which is a measure of whiteness of a surface.Whiter the surface, more would be the reflective value of the incident sunlight on these surfaces.The Solar Reflective Index(SRI) in conjunction with Thermal Emittance(TE) is to be taken into account while evaluating the efficacy of a cool roof paint/coating.Therfore, the higher the SRI value is, the greater ability the coating has to reject solar heat absorption, maintaining a much cooler indoor ambient air temperature even without the need of air conditioning.The SRI solar reflectance index is a scale of 1 to 100 that is a measure of a roof’s combined thermal properties.
How to calculate SRI values?
By sending a small sample of your building material, the Surface Optics Measurements Lab can perform SRI testing in accordance with ASTM and LEED requirements. Lab will provide a report that includes the values shown in Table 1 for the provided sample(s). The SRI Report for a material can be submitted as documentation for LEED heat island reduction credit.
| Value | Test Method |
|---|---|
| Solar Reflectance | ASTM C1549 – Standard Test Method for Determination of Solar Reflectance |
| Thermal Emittance | ASTM E408 – Standard Test Method for Total Normal Emittance of Surfaces Using Inspection-Meter Techniques |
| Solar Reflectance Index | ASTM E 1980 – Standard Practice for Calculating Solar Reflectance Index of Horizontal and Low-Sloped Opaque Surfaces |
Surface Optics does not perform aged SRI testing.
In India Confederation of Indian Industry (CII) leading the way for sustainable practices. Confederation of Indian Industry (CII) formed the Indian Green Building Council (IGBC) in year 2001. Indian Green Building Council (IGBC) has licensed the LEED Green Building Standard from the USGBC. IGBC facilitates Indian green structures to become one of the green buildings.
LuminX solar heat reflective roof cooling coating for roofs
According the results reported by CEPT University – Ahemdabad for our LuminX cool roof test samples: LuminX Solar reflective summer cool roof coating provides the highest reflectivity capabilities availble to the roof coating market. LuminX delivered highest long-term solar reflectance and SRI rating of all the roof coatings in the market. This roof coating is excellent choice for professionals for rejecting heat absorption, lowering energy cooling costs and creating a cooler, more comfortable environment inside the building.
How to maintain high SRI values on your roof surfaces?
SRI value of a surface can change over time, subjected to many factors.
- Weathering: agents like rainwater and wind can erode surfaces, thereby decreasing SRI values.
- Dust accumulation: dust and soot can stick to roof surfaces and decrease the whiteness of roof surfaces,henceforth decreasing SRI values
- Biological growth: occurrence of moss, algae on roof surfaces can also lead to decrease in SRI values.
How to prevent SRI values from degrading?
A freshly prepared roof with solar reflective coating would definitely have a high SRI value as compared to a roof surface which has been denuded.In order to get the best results, proper maintainence and inspection of roofs is important.
Some of the tips are as follows:
- Ensure proper drainage of roof surfaces: rain water accumulation of rainwater on roof surfaces must be prevented.
- Floor preparation: ensuring proper cleaning of roof surfaces with professional tools before applying roof paint.
- Removing all forms of microbiological growth from the roof
- Timely cleaning of roof surfaces to remove the dust accumulation.
Why choose LUMINX to maintain a consistent SRI over long periods of time?
Besides having a high SRI value as established by vigorous lab tests,LuminX Roof Paint has certain unique properties
- Easy cleaning: its an acrylic based paint and is highly hydrophobic in nature. This ensures that the surfaces coated with LuminX can be easily cleansed.
- Product is anti fungal: preventing microbial growth on roof surfaces.
- Professional paint work: LuminX has a professional team which prepares the roof before coating the roof.This step is of great importance.
- Provides warranty: LuminX is confident of delivering the best product at the most affordable price.
