Our project includes a water feature that is designed to retain all rainwater falling on the site up to the 1.5 year, 24 hour peak discharge rate. Please confirm that the area of the water feature will be counted as a pervious surface for purposes of calculating compliance with Sustainable Sites Credit 7.1, Heat Island, Non-roof.
For urban heat island calculations, water features are not required to be counted as impervious surfaces. If the water feature is made from a material that becomes an exposed impervious surface when the water feature does not contain water, the project team should include it as a non-roof impervious surface in the calculations. This could be done by developing a methodology for inclusion in the calculations based on area and percentage of time exposed. If the exposed material has high albedo as defined by the credit requirements, including it in the calculations could contribute towards credit achievement. Applicable internationally.