Green Code Technical Standard 1
NRW Measurement Protocol, Energy Accounting, and Compliance Verification
§1 — Scope & Definitions
GCTS-1 defines the measurement, accounting, and verification requirements for Green Code Protocol compliance in municipal water systems and data center facilities.
This standard applies to: (a) municipal water utilities proposing to deploy acoustic non-revenue water detection under the Green Code Protocol; (b) data center facilities seeking compliance certification for municipal impact-fee structures based on the GCP ordinance model; (c) third-party auditors verifying compliance with either category.
This standard does not apply to: residential water use, agricultural irrigation systems, or any system with annual production volume below 500 million gallons.
| Term | Definition | Source |
|---|---|---|
| NRW | Non-Revenue Water: system input volume minus authorised consumption, expressed as percentage of system input or as absolute volume (m³/day) | IWA/AWWA M36, 4th Ed. |
| ILI | Infrastructure Leakage Index: ratio of current annual real losses to unavoidable annual real losses. ILI ≤ 1.0 is theoretical minimum | IWA/AWWA M36 §4.3 |
| PUE | Power Usage Effectiveness: total facility power / IT equipment power. Lower is better; 1.0 = theoretical perfect efficiency | The Green Grid / ASHRAE |
| WUE | Water Usage Effectiveness: annual site water usage (litres) / IT equipment energy (kWh). Target ≤ 1.8 L/kWh per The Green Grid | The Green Grid WUE v1.0 |
| Compliance facility | Any data center or AI compute facility exceeding the proposed capacity threshold (50 MW per-facility cap) within the GCP ordinance jurisdiction | GCTS-1 §4.1 |
| Closed-loop cooling | Cooling system where water circulates without evaporative discharge to the local water table; heat exchanged to ambient air or ground loops | ASHRAE TC 9.9, GCTS-1 §4 |
§2 — NRW Measurement Requirements
All NRW calculations under GCTS-1 use the IWA/AWWA M36 water balance methodology exclusively. No proprietary calculation method is permitted.
Required inputs: System Input Volume (metered), Authorised Consumption (billed metered + billed unmetered + unbilled metered + unbilled unmetered), and Apparent Losses (customer meter under-registration + unauthorised use).
NRW = System Input Volume − Authorised Consumption
Baseline assessment: Minimum 30-day continuous metered water balance required before pilot sensor deployment. Utility must confirm meter calibration within 12 months prior.
Source: AWWA M36 Water Audits and Loss Control Programs, 4th Ed.
This calculation method is used by USEPA ENERGY STAR Water Systems, AWWA WSPA, and WaterWatch Australia. It is the globally adopted standard — GCTS-1 applies it, does not replace it.
Projected NRW reduction range derived from IWA/AWWA M36 district metered area methodology applied to reference baseline conditions representative of aging US municipal pipe networks (15–30% NRW baseline range, AWWA SOWI 2024).
Actual NRW reduction for any specific system is quantified post-pilot from the water balance data collected under §2.1. The 12–28% range is a modeled design target — not a performance claim for any specific deployment.
§3 — Energy & Water-Use Accounting (>10 MW Facilities)
Compliance facilities must report PUE and WUE on a quarterly basis using The Green Grid standard metrics.
All compliance facilities must calculate and report annualised PUE quarterly to the municipal authority and to the GCP public ledger. PUE must be calculated per The Green Grid PUE v2.0 methodology.
Target PUE: ≤ 1.2 for new construction. ≤ 1.5 for retrofit of existing facilities. These are design targets; actual values are reported as-measured.
Precedent: EU Code of Conduct on Data Centre Energy Efficiency (Tier 3 target: PUE 1.2); ASHRAE A1–A4 thermal envelope standards.
All compliance facilities must calculate and report annual WUE (litres per kWh IT load) to the municipal authority and to the GCP public ledger. WUE is calculated per The Green Grid WUE v1.0 methodology.
Target WUE: ≤ 1.8 L/kWh for new construction. Retrofit facilities report actual WUE with reduction roadmap submitted within 90 days of ordinance effective date.
§4 — Closed-Loop Cooling Requirement
Compliance facilities must operate closed-loop cooling systems that do not discharge to the local water table. This requirement is based on precedented municipal impact-fee structures.
Compliance facilities must use one of the following approved cooling architectures: (a) air-cooled dry cooler with closed-loop primary circuit; (b) ground-source heat exchange with zero evaporative discharge; (c) direct liquid cooling (DLC) with closed-loop secondary coolant circuit and zero evaporative tower discharge; (d) immersion cooling with closed-loop dielectric fluid.
Open-loop evaporative cooling towers drawing from or discharging to municipal water supply are not permitted for compliance facilities.
Precedent policies: Clark County (NV) data center water-use ordinance (2022); Denver Water non-potable reuse mandate (2021); Singapore IMDA Green Data Centre Standard (2023). GCTS-1 applies these principles — no jurisdiction has enacted this specific ordinance yet.
§5 — Compliance Verification Process
Compliance is verified using the methodology described in the Verification Methodology page. This section summarises the requirements; see that page for full technical detail.
All sensor readings, water balance calculations, PUE/WUE figures, and audit findings are written to a SHA-256 hash-chained append-only log. Log integrity is independently verifiable by county staff using the published open-source tool.
Quarterly audits are conducted by an independent auditor selected and contracted by the municipal authority. Audit statements are published to /trust/.
ZK verification layer under development — not production-ready. When deployed, the ZK layer will provide cryptographic proof-of-calculation-correctness without exposing raw sensor data. It supplements, it does not replace, the physical audit under §5.1.
No performance figures (latency, proof size, energy cost) are specified in this version of GCTS-1 pending circuit development completion.
§6 — Protocol Hardening Additions (§PH-1 to §PH-6)
Added 2026-07-15. These sections address systemic risks identified during internal audit review.
| Section | Topic | Status |
|---|---|---|
§PH-1 | Sensor calibration anti-tamper protocol — physical seal + calibration certificate chain | PROPOSED |
§PH-2 | Water-Backed Token (WBT) reserve architecture — $0.10/1,000 L internal accounting reference rate; not a market instrument | PROPOSED |
§PH-3 | ZK verification layer specification — Rust Bulletproofs / Halo2 circuit design; open repository; no production timeline | PROPOSED |
§PH-4 | Cross-jurisdiction data portability — audit log export format (JSON-LD), county data ownership clause | PROPOSED |
§PH-5 | Adverse-event reporting — mandatory 48-hour disclosure to county authority on sensor failure or data gap >6 hours | PROPOSED |
§PH-6 | Hardware lifecycle — end-of-life sensor disposal, firmware update cadence, and replacement BOM disclosure | PROPOSED |
§7 — Versioning & Changelog
GCTS-1 follows semantic versioning. Major version = breaking change to a measurement method. Minor = additive. Patch = editorial.
Request via engineering@silxi.pages.dev
§8 — How to Submit Peer Review
Submit Peer Review
GCTS-1 is an open draft standard. Peer review is explicitly invited from water engineers, municipal utility managers, data center operators, and independent standards experts. All substantive comments will be addressed in the next version changelog.
What to review:
- §2 NRW measurement method — correctness against IWA/AWWA M36
- §3 PUE/WUE targets — alignment with current industry benchmarks
- §4 Cooling requirement — technical feasibility for retrofits
- §5 Audit process — adequacy for independent verification
- §PH-1 to §PH-6 — completeness of hardening additions
- Any claim, figure, or requirement you believe is incorrect or insufficiently evidenced
Reviews acknowledged within 5 business days. All reviewers credited in the changelog unless anonymity requested.