The Village of Norridge requires that every residential property within the Village limits to have at least 65% green space on the property. This means that the homeowner can only have 35% of the property consist of impervious surface areas such as the building, garage, driveway, and patios. Any resident in violation of this policy can face fines and may be forced to make changes to their property. In the past, the Village would calculate the green space percentage by measuring the area of the parcels and the features using a ruler and a pencil. The Village asked the GIS department to come up with something that would aid in their analysis.
A map was created showing the percentage of green space for each parcel in the community. The percentage was calculated by combining all the building foot prints, driveways, garages, and sidewalks into one feature then dividing the area of impervious surface in a parcel by the area of the parcel itself. Even though the number is not necessarily exact due to some of the features, like patios, not being collected in the data, it provides a good starting point for any calculations and allows the village to see what properties may be in violation of the ordinance and then act accordingly. By using GIS, the village is able to cut down the amount of time calculating the green space area by hand and find properties that may be in violation that they might not have had a reason to check in the past.