Writing Data Center Standards That Hold Up

1. What this is

This is the companion to A Framework for Public Deliberation on Data Center Siting (Part 1). Part 1 covers how a local body reaches a defensible answer. Part 2 covers what the resulting standard has to say so that it can be measured, checked and enforced.

It is written for planning staff drafting a data center ordinance or development standard, for the attorneys reviewing it, and for the commissions and councils adopting it. It applies whether or not a task force was convened.

It takes no position on whether a jurisdiction should permit, restrict, condition or prohibit data centers. It is not legal advice. Whether a provision is lawful and enforceable in a given jurisdiction is a determination for that jurisdiction's attorney.

2. Why it is needed

Local data center rules are being written quickly, often during a pause with a fixed end date. As of October 27, 2026, the Calyx register records 157 cities and counties in 31 states with a local pause in effect. Most of them will adopt standards before their pause ends. The record of rules already adopted shows three recurring problems.

Text and numbers are borrowed without a local basis. Drafting from a neighbor's ordinance is reasonable; most staff do it. But definitions, thresholds and setbacks travel with the text. The same definition sentence appears word for word in a Georgia city's zoning ordinance and in an Ohio city's 2026 data center ordinance. A borrowed number is only as good as the conditions it was written for.

Standards tie limits to a baseline without saying how to measure it. Several adopted noise standards limit sound to the ambient level found in a baseline study, but state no metric, measurement standard, averaging period, time of day or tonality provision. Where the baseline on file is a short daytime sample, the limit cannot be checked at night, and any reading can be contested on method alone.

Duties continue after approval, but no one is assigned to receive them. Post-construction studies, annual reports, generator test notices and financial certifications are common. In the record, most such filings are not posted, and many are visible only through a public records request. A requirement that no office reads is not enforced.

3. The test every standard must pass

Apply these seven questions to each standard in the draft. Any question the text does not answer is where a dispute will start.

4. The decisions, one by one

Each decision below lists what the jurisdiction must decide, the local data it needs, what the rule should state, and what record it should keep. None has a single correct answer. Each answer should trace to local conditions. Model provisions for several of them are available to public bodies on request (Appendix A).

4.1 Definition and threshold

• Decide: what counts as a data center (purpose, floor area, electrical load, or a combination), and how accessory server rooms and modular or containerized installations are treated.
• The trade-off: a purpose-only definition excludes a business's server room but includes a small containerized facility. A floor-area or load threshold excludes small facilities. Adopted thresholds range widely: one Arizona city's large-scale tier begins above 25,000 square feet or 20 MW; a Massachusetts executive order applies above 25 MW of peak demand; a proposed Massachusetts moratorium sets no size floor and names modular or networked facilities that function together as one.
• Local data: facilities already operating or proposed, with their floor area and electrical load.
• Write into the rule: the threshold, how multiple buildings or units on one site are aggregated, and how load is measured (design load, service capacity, or metered demand).

4.2 Where they may locate

• Decide: districts, setbacks, buffers, acreage limits.
• Local data: a map of sensitive receptors (homes, schools, hospitals, care facilities, trails), measured ambient sound at those receptors, and terrain.
• Write into the rule: each distance, from what to what, and the basis for it.
• Caution: a setback copied from another jurisdiction carries that jurisdiction's geography. Record why the distance fits here.

4.3 Noise

• Decide: a fixed limit, a limit relative to a measured baseline, or both (for example, the lower of a fixed number and baseline plus a margin).
• Write into the rule: the metric (A-weighted, plus C-weighted or a low-frequency measure for chillers, fans and transformers); a named measurement standard (for example, ANSI S12.9 or ISO 1996-2) and sound level meter class (for example, IEC 61672-1 Class 1); the measurement point and height; the averaging period and any maximum; separate day and night limits; and a tonal penalty.
• Baseline: measured before approval under the protocol in Section 5.
• After construction: a study at peak mechanical operation within a stated period after occupancy, then on a stated schedule, under the same protocol.
• Complaints: a stated trigger for a measurement directed by the jurisdiction.
• Construction period: hours and limits for construction, which is often the loudest phase and is frequently unaddressed.

4.4 Generators

• Decide: permitted uses (outage, utility request, testing), testing hours and frequency, emissions tier, and dispatch order where batteries are installed.
• Write into the rule: who receives test logs and how often; advance public notice of routine tests and where it is posted.
• Note: verifying run hours and engine condition is a mechanical inspection matter for a qualified inspector.

4.5 Water and cooling

• Decide: source, cooling type, any volume threshold that triggers review, and reporting.
• Write into the rule: annual reporting of water use to a named office, and whether the report is posted.

4.6 Electrical service and rates

• Rates and cost allocation are generally set by the state utility commission and the utility, not by local zoning.
• A local rule can require disclosure of service terms that matter locally (capacity, curtailment, who pays for upgrades) and documented coordination with the utility before approval.

4.7 Payments and security

• Decide: payments in lieu of taxes, community funds, the job and investment minimums behind any incentive, and decommissioning security (amount, form, review interval).
• Write into the rule or agreement: what is certified, by when, to whom, and what follows a shortfall.

4.8 The obligations calendar

• List every duty that continues after approval: what is required, when it is due, to whom, and where it is posted.
• Name the office responsible for receiving and reading each filing.
• Adopt the calendar with the rule (Section 7 has a format; model text is available on request).

5. Baseline sound measurement protocol

A limit tied to a baseline is only as good as the baseline. Ambient conditions cannot be reconstructed after construction begins, so the baseline must be measured first. At minimum:

1. Who: an independent acoustical professional selected by the jurisdiction. The applicant may pay; the applicant does not select.
2. Where: at the sensitive receptors nearest the site, and at the property line, at stated heights.
3. When: continuous measurement for at least seven consecutive days, including nights and a weekend, with weather logged. Seasonal conditions noted.
4. What is reported: hourly equivalent levels (Leq), a background statistic (for example, L90), maximum levels, A- and C-weighted, and one-third octave bands to identify tones.
5. Instruments: Class 1 meters, field-calibrated before and after each deployment, with calibration records filed.
6. Filing: the raw data, not only a summary, filed with a named office and retained for the life of the approval.
7. Repeat: post-construction and periodic studies use the same protocol, points and reporting, so results compare directly.

6. Before drafting: local data checklist

• Existing and proposed facilities, with floor area and electrical load.
• Sensitive receptor map.
• Baseline sound at receptors, day and night (Section 5).
• Water source, capacity and current demand.
• Utility capacity and planned transmission or substation work.
• The comparable rules under consideration: where each one's text and numbers came from, the authority under which it was adopted, and whether it has been enforced or challenged.

7. After adoption: the obligations calendar

One row per continuing duty, adopted with the rule and kept current by the receiving office:

Rows are illustrative. Each jurisdiction sets its own duties, intervals and offices.

8. Using borrowed text

Adopting a provision from another jurisdiction is often sensible. Before doing so, record:

1. The source of the text and the date it was adopted there.
2. Whether the source jurisdiction's authority matches this one's (for example, home rule, county zoning powers, state preemption).
3. Why each number fits local conditions, with the local data that supports it.
4. Whether the provision has been enforced or tested since adoption, and with what result.

9. Separation of determinations

• Legal sufficiency of any provision: the jurisdiction's attorney.
• Mechanical condition of generators and equipment: a qualified inspector.
• Measurement: an independent acoustical or environmental professional, selected by the jurisdiction.
• The policy choice: the elected body.

Appendix A — Model provisions

Model ordinance provisions for the decisions in Section 4 (definition and threshold, noise, generators, water reporting and the obligations calendar) are available to public bodies on request, with the PDF of this framework. Every value in them is left blank, to be filled from local data. Request them with your name, jurisdiction and role.

About this document

© 2026 Calyx Intelligence LLC. All rights reserved. A public body may use this framework in its own deliberation and rulemaking, and may adopt provisions adapted from it into its own ordinances, without fee. Any other reproduction, distribution or commercial use requires written permission from Calyx Intelligence. Any workstream it describes may be performed by staff, by any contractor, or by Calyx under separate engagement; nothing here reserves any of them.

The examples are drawn from the Calyx public register of data center provisions, where each entry is marked for whether it was read in the original document. Calyx does not provide advocacy, engineering design, certification of compliance, or legal determination.

register.calyxos.ai · calyxos.ai

Part 2, version 1.1, October 27, 2026. Revisions are versioned and dated.