Where groups of four or more contiguous businesses are located together or where a lesser number of stores total not less than 20,000 square feet of gross leasable area, one common freestanding sign denoting the name of the shopping facility shall be permitted, not exceeding 80 square feet (40 square feet per side) and with its bottom panel not more than eight feet above grade. All other signs shall be attached to buildings, of a wall, projecting or soffit-type, and coordinated in material, shape, lettering, color and/or decorative elements. Total signage permitted for the entire shopping center shall be calculated at the rate of two square foot of sign per lineal foot of building frontage, plus 1/4 square foot of lot frontage, not to exceed 450 square feet (including all sides of signs conveying a message), whichever is less.