Buffalo Grove in Illinois has created a Planned Unit Development (PUD) section within its Code of Ordinances, Section 17.28.050. Residential dwelling units within this PUD district shall be calculated on the net acreage of the site, where percentages will be applied to the base density. The PUD section does include a solar energy incentive when calculating the percentages for residential dwelling units. Under the incentive, Buffalo Grove will allocate three percent for the provision of solar housing design elements or if one hundred percent of the homes have substantial south/southeasterly facing windows and two percent for use of landscaping as a means of protecting the structure against impediments against solar energy systems.