We want to use paving block as one of the hardscape surfaces. Space between block can be fill with chippings/grit (photo: http://www.semmelrock.pl/semmelrock/export/sites/polen/_data/products/he...) or grass (photo: http://www.semmelrock.pl/semmelrock/export/sites/polen/_data/products/he...). As it can be seen at photos blocks are laid out in a pattern that exposes areas of the ground allowing vegetation to grow in the open cells. In case we use grass it will not need irrigation. Can we count it in our calculation to achieve this credit? Can we use grit according to architect’s intent or should it be grass?