Window-to-Wall ratio calculation to meet the GRIHA compliance

Window-to-Wall Ratio determines the amount of natural light that can enter a building through fenestration. To conduct the Window-to-Wall Ratio (WWR) compliance to meet GRIHA compliance, follow these steps:

1. Determine the prescribed levels of WWR and/or Skylight-to-Roof Ratio (SSR) as per Appraisals 11.1.1 under Criterion 11: Achieving indoor comfort requirements (visual/thermal/acoustic) of the GRIHA Manual V-2015 i.e. WWR does not exceed 60%.
2. Calculate the total area of windows and walls in the building. This can be done using the building design drawings and specifications.
3. Calculate the WWR by dividing the total window area by the total wall area. Ensure that the WWR does not exceed the prescribed levels.
4. Similarly, calculate the SSR by dividing the total skylight area by the total roof area. Ensure that the SSR does not exceed the prescribed levels.

Here’s an example to illustrate the calculation of WWR compliance:

Assume a building has a total wall area of 1000 square meters and a total window area of 200 square meters.

WWR = (Total Window Area / Total Wall Area) x 100%
= (200 / 1000) x 100%
= 20%

If the prescribed WWR limit is 20%, then the building meets the compliance requirement.

It’s important to note that the WWR compliance is just one aspect of the daylight compliance requirements of GRIHA, and additional criteria must also be met to achieve compliance.