Plain-language definitions of terms commonly used in zoning, planning, and municipal government documents. This glossary focuses on terms commonly used in Illinois data center zoning, permitting, infrastructure, and public finance documents. Some terminology varies by municipality.
- Air Permit
- A regulatory approval that may be required for equipment that emits air pollutants, such as diesel backup generators.
- Annexation
- The process by which a municipality incorporates land that was previously unincorporated or part of another jurisdiction. Developers often seek annexation to gain access to municipal utilities or more favorable zoning.
- Backup Generator
- On-site equipment used to provide electricity when utility power fails. Data centers often use multiple backup generators to maintain operations during outages.
- Comprehensive Plan
- A municipality's long-range policy document that guides future land use, growth, transportation, and infrastructure decisions. Zoning and development decisions are often expected to align with the comprehensive plan.
- Cooling System
- The equipment used to remove heat from servers and maintain proper operating temperatures. Depending on the design, cooling systems may rely on air cooling, chilled water, evaporative cooling, or other methods.
- Data Center
- A building or campus that houses computer servers and related equipment used to store, process, and transmit digital information. Data centers typically require significant electricity, backup power systems, and cooling infrastructure.
- Development Agreement
- A negotiated agreement between a developer and a local government that sets out project-specific obligations such as infrastructure improvements, construction timelines, incentives, and public benefits.
- Enterprise Zone
- A designated area where businesses receive state and local tax incentives to encourage economic development. Approval typically requires action by the Illinois Department of Commerce and Economic Opportunity.
- FOIA (Freedom of Information Act)
- Illinois law (5 ILCS 140) that gives residents the right to inspect and copy public records held by government agencies. Requests must be submitted in writing and agencies must respond within 5 business days.
- Noise Study
- A technical report analyzing expected sound levels from a project and whether those levels comply with applicable regulations or conditions of approval.
- Planned Unit Development (PUD)
- A type of zoning approval that allows a developer to build a project under a customized set of standards, often in exchange for community benefits. Requires approval from the planning commission and governing board.
- Rezoning
- A change to the official zoning designation of a parcel of land. Requires a petition, public notice, a public hearing, and a vote by the governing body.
- Site Plan
- A detailed plan showing the arrangement of buildings, parking, access drives, utilities, landscaping, lighting, and stormwater facilities on a property. Site plan review is often required before building permits are issued.
- Special Use Permit
- A permit allowing a land use that is not automatically allowed in a given zoning district but may be approved if certain conditions are met. Requires a public hearing.
- Stormwater Management
- Measures used to control runoff from rainfall or snowmelt so that development does not increase flooding, erosion, or water pollution.
- Substation
- An electrical facility that converts or routes power from the grid to end users. Large data center projects often require a new or expanded substation to meet power demand.
- TIF (Tax Increment Financing)
- A public financing mechanism where future increases in property tax revenue within a designated district are set aside to fund development costs within that district. Existing taxing bodies (schools, park districts) do not receive those incremental revenues for the life of the TIF.
- Traffic Impact Study
- A report evaluating how a proposed development will affect traffic volumes, road operations, and intersection performance, especially during peak periods or construction.
- UPS (Uninterruptible Power Supply)
- Equipment that provides immediate short-term power to critical systems when utility service is interrupted, usually until backup generators are operating.
- Variance
- An approval allowing relief from a specific zoning standard, such as building height, setback, or lot coverage. Variances do not typically change the underlying zoning district or permitted uses.
- Water Use
- The amount of water a facility consumes for cooling or other operational needs. Water demand can be an important issue in public review of data center proposals.
- Zoning
- A system of land-use regulations that divides a municipality into districts and specifies what types of buildings and activities are allowed in each district.