Principal data centers are allowed only in the Industrial Mixed-Use (IM) and Industrial General (IG) districts and require a special permit with conditions. Accessory data centers may be allowed only in specified residential, commercial, mixed-use, and industrial districts; in residential districts and the Mystic Downtown District, they cannot support a residential use and may be accessory only to a permitted institutional or commercial use. The permitted-use table classifies data centers as special-permit uses in IM and IG and limits accessory data centers to specified districts.

A data center, excluding space for personnel, office, and maintenance functions, may not exceed 12,500 square feet of total floor area, whether located in one structure or multiple structures. The size of any Data Center ... must not exceed 12,500 square feet.

An accessory data center may not exceed 20% of the principal use's gross floor area or 1,000 square feet, whichever is less, and must comply with the underlying district's dimensional, building, and lot standards. Any Accessory Data Center must be no greater in gross square footage than 20%.

A lot containing a data center generally must be at least 1,500 feet from another lot containing a data center, measured between the closest property lines. The separation requirement does not apply to accessory data centers, but an accessory data center may not be colocated with a principal data center. A lot with a Data Center cannot be located within 1,500 feet.

Facility cooling using water-evaporation techniques is prohibited. Facility cooling using water evaporation technique is prohibited.

On-site power generation using fossil fuels is prohibited, except when needed because of an unforeseen loss of off-site power. On-site power generation using fossil fuels is prohibited.

Data centers must comply with Connecticut noise standards for Class B emitters, and confirmation of compliance must be submitted to the Office of Planning and Development Services before a Certificate of Site Plan Compliance is issued. A Data Center must meet the standards for Class B emitters.

A written fire-suppression plan approved by the applicable fire chief is required, and fire-suppression systems must comply with National Fire Protection Association codes and standards. A written fire suppression plan acceptable to and approved by the Fire Chief.

A site-plan applicant must submit an agreement with the water and electric utilities demonstrating that the proposed data center's utility demands can be met at the site. An agreement with water and electrical utilities demonstrating that the Data Center’s utility demands can be met.

Data centers on lots abutting a district other than IG or IM, or abutting an existing residential use, must comply with the zoning regulations' buffer-area standards. All Data Centers on a lot abutting a property in any zoning district other than IG and IM.

A temporary moratorium added on July 15, 2022, restricted data-center activity during the moratorium period; Section 11.1 was later deleted on July 14, 2023, when Section 5.1-6.F governing data centers was added.

Allows data centers as principal uses in the Industrial Mixed-Use (IM) and Industrial General (IG) districts, subject to special-permit, site-plan, and other stated development requirements, providing a zoning pathway without a separate zoning amendment for each facility.

Allows data-center facilities to include the buildings, equipment, and associated utility infrastructure needed for their operation, subject to applicable development standards and approvals.

Allows accessory data centers in many residential, commercial, mixed-use, and industrial districts without a special permit; in residential districts and the MDD, they may be accessory only to permitted institutional or commercial uses, not residential uses.

Permits a principal data center to contain up to 12,500 square feet of data-center space, excluding personnel, office, and maintenance areas.

Permits an accessory data center to occupy up to 20% of the principal use's gross floor area or 1,000 square feet, whichever is less, while requiring compliance with applicable district, building, and lot standards.

Allows on-site fossil-fuel power generation for emergency backup when there is an unforeseen loss of off-site power.

Allows a data-center application to demonstrate that its proposed water and electrical demands can be met through an agreement with the relevant utilities.

Allows a lawfully established data center to continue as a legal nonconforming use if it later becomes prohibited, subject to nonconforming-use rules; certain alterations or changes to another nonconforming use may require a special permit, and expansions remain subject to limits.

Deletes the temporary moratorium on data centers, removing the temporary prohibition on data-center applications.

Temporary application-processing barrier for data centers over 5,000 square feet: no covered application was to be accepted or processed by the Planning and Zoning Commission or Office of Planning and Development Services. Contemporary reporting corroborates a halt to all applications for facilities larger than 5,000 square feet.

No affirmative incentive or approval entitlement is identified in the moratorium sources reviewed. Its threshold covered only data centers larger than 5,000 square feet; exclusion from this moratorium does not establish that smaller facilities were otherwise permitted. The later replacement amendment separately conditionally allows data centers and accessory data centers in certain zones; that is not an incentive created by the 2022 moratorium.