Status: implemented

Implemented — this change has shipped.

RFC 0039: Data-center module — the first product module on a module-declared asset class

RFC 0003 opened the asset-class enum to modules and RFC 0006 shipped the first module — but hospitality is a builtin class, so the module system's two halves have never been exercised together on a real vertical. Data centers are the obvious first: they are the asset class every "why not industrial?" conversation in RFC 0003 was about, the revenue unit is kilowatts rather than square feet, and the per-unit metrics the §XIII size-intensive registry refuses to hand a custom class (§X.2.4) are exactly the ones the vertical runs on. If RFC 0003 generalizes, this module proves it; where it does not, this RFC is where the gap gets named. No spec change; protocol and format versions do not move.

Summary

Ship @uwmd/module-data-center, a second reference module built against the published surface of @uwmd/core, declaring the custom asset class org.uwmd.data_center (fallback industrial), three sections (dc_capacity, dc_power, dc_revenue), eleven kilowatt-denominated calculations, and seven validations. The module is the first shipped consumer of declares_asset_classes; the existing com.example.data_center fixture under conformance/modules/asset-classes/ stays as the resolution fixture and is not replaced. A new example document and a conformance/modules/runtime/ suite land with it.

Motivation

• RFC 0003 has a fixture consumer but no product consumer. The resolution rules (§X.2), MOD-FALLBACK-001, MOD-DEPENDENCY-UNDECLARED and the three-segment identifier grammar are exercised only by a four-line fixture manifest that declares one required_sections entry and nothing else. Whether a module that declares a class and supplies sections, calculations, and validations for it composes cleanly — required sections from the declaration versus required: true on the section, the fallback render of a document whose headline numbers live in module sections a Tier-1 reader cannot interpret — is unverified. RFC 0006's lesson was that the module system's real gaps only surfaced when a real module was built; the custom-class half deserves the same treatment.
• Data centers are being underwritten as industrial today, which is the misuse RFC 0003 §Motivation named. The standard sections have nowhere to put critical IT load, PUE, redundancy topology, rent per kW-month, or the power pass-through terms that decide whether an operator's margin is 60% or 20%. A data-center deal authored against the standard sections loses every number a buyer actually asks about, and price_per_sqft on a powered shell is a meaningless denominator.
• The per-unit question is the real test of §X.2.4. A hotel is priced per key and the builtin size-intensive registry knows it. A data center is priced per commissioned kW (or MW) and the registry cannot know it — §X.2.4 refuses custom classes an entry on purpose. So the module must supply price_per_commissioned_kw and noi_per_commissioned_kw itself, from the standard sections' figures and its own capacity section. Whether that is enough, or whether a later RFC needs to let a module declare a per-unit denominator under controlled conditions, is a question this RFC is designed to answer with evidence rather than argument (§Unresolved).

Proposed change

New package: @uwmd/module-data-center

packages/uwmd-module-data-center/
├── package.json
├── scripts/emit-manifest.mjs   # the RFC 0006 shape: TS is the source of truth, dist/manifest.json is emitted
├── src/
│   ├── index.ts                # the typed ModuleManifest + exports
│   ├── view-models.ts          # SectionViewModel[] for the three sections
│   └── index.test.ts
├── test/fixtures/
│   └── mesa-gateway-data-center.uwx.md
└── README.md

TypeScript is the manifest source of truth and dist/manifest.json is generated at build time — the RFC 0006 implementation note 2 decision, adopted as-is.

Identifiers

	Value	Rule
Module id	org.uwmd.datacenters	reverse-DNS, the project's own namespace (as org.uwmd.hospitality)
Asset-class id	org.uwmd.data_center	three segments; final segment is not a builtin (§2.2a, INVALID-ASSET-CLASS-002)
Fallback	industrial	stated: a reader without the module renders property, noi_model, dcf, debt under the industrial view; the dc_* sections render as generic blocks

The fallback is deliberate rather than omitted. RFC 0003 says to omit fallback when no approximation is honest; here one is — the standard sections of a data-center deal are ordinary industrial real estate (a building, a lease, an NOI), and only the module sections are not. What the fallback reader loses is stated in §Compatibility.

The com.example.data_center class in conformance/modules/asset-classes/ is a different namespace and stays untouched. It is the resolution fixture (four byte-identical documents, verdict depends on the reader); this module is a product. MOD-ASSET-CLASS-CONFLICT-001 does not apply — different identifiers.

Manifest

const MANIFEST: ModuleManifest = {
  manifest_version: '1',
  id: 'org.uwmd.datacenters',
  name: 'Data Center Underwriting Module',
  version: '0.1.0',
  description: 'Declares the org.uwmd.data_center asset class; adds capacity, power-economics and revenue sections; kW-denominated calculations; PUE, utility-feed and utilization validations.',
  authors: ['UW Markdown contributors'],
  license: 'MIT',
  requires_protocol: '>=2.5.0',
  requires_format: '>=1.1',
  requires_tier: 'tier-3-calc-host',
  declares_asset_classes: [{
    id: 'org.uwmd.data_center',
    display_name: 'Data Center',
    fallback: 'industrial',
    required_sections: ['dc_capacity'],
    optional_sections: ['dc_power', 'dc_revenue'],
  }],
  sections: [ /* below */ ],
  calculations: [ /* below */ ],
  validations: [ /* below */ ],
  view_models: [...DATA_CENTER_VIEW_MODELS],
};

requires_protocol: '>=2.5.0' because the module's fixture carries dcf.returns.tax_basis (RFC 0038) and its validations are read alongside the RFC 0037 coverage channel; there is nothing in the module that needs 2.5.0 mechanically, but a module pinned below the protocol its own fixture needs is a lie the loader cannot catch.

Sections

Every rate is a fraction (format-wide rule); every power figure is in kW (the market quotes MW for capacity and $/kW/month for rent — one unit avoids the ×1000 mistake that the hospitality module's occupancy-as-percent rule exists to catch in its own domain).

dc_capacity (required — it is what makes the document a data center):

Field	Type	Meaning
critical_it_load_kw	number ≥ 0	Commissioned critical IT load — the capacity that can be sold today.
planned_it_load_kw	number ≥ 0	Full build-out critical load. Equals critical_it_load_kw when no further phases exist.
contracted_it_load_kw	number ≥ 0	Load under signed contract (leased/committed), including pre-leased future phases.
utility_feed_kw	number ≥ 0	Utility power available at the meter today.
design_pue	number ≥ 1	Design power usage effectiveness: total facility power ÷ IT power.
measured_pue	number ≥ 1 or null	Trailing measured PUE; null when the facility is not yet operating.
redundancy	enum n, n_plus_1, n_plus_2, 2n, 2n_plus_1	Electrical/mechanical topology. Not the Uptime tier — see §Unresolved.
raised_floor_sf	integer ≥ 0 or null	White space. Null for powered shells.
design_density_kw_per_rack	number ≥ 0 or null	Average design density.

dc_power (optional):

Field	Type	Meaning
utility_rate_per_kwh	number ≥ 0	Blended $/kWh, all charges.
billing	enum metered_pass_through, all_in, breakered	How power is billed to tenants.
power_margin	number ≥ 0 or null	Landlord margin on power as a fraction of cost; meaningful only under all_in / breakered.
stated_annual_power_cost	number ≥ 0 or null	The operator's stated annual utility bill, when known.

dc_revenue (optional; the calcs that need it stay null without it, §VIII.2):

Field	Type	Meaning
lease_type	enum powered_shell, wholesale_turnkey, retail_colocation, hyperscale_build_to_suit	Predominant lease structure.
rent_per_kw_month	number ≥ 0	Weighted-average contracted rent, $/kW/month, on contracted_it_load_kw.
interconnection_revenue_annual	number ≥ 0	Cross-connects, meet-me-room.
services_revenue_annual	number ≥ 0	Remote hands and other services.
market_rent_per_kw_month	number ≥ 0 or null	Comp rent; null means no comp set was obtained.

Calculations

Declaration order is load-bearing — the runtime threads prior_results, so each row may read only the rows above it.

id	Formula	Unit	round_to
utilization	dc_capacity.contracted_it_load_kw / dc_capacity.critical_it_load_kw	%	4
commissioned_share	dc_capacity.critical_it_load_kw / dc_capacity.planned_it_load_kw	%	4
facility_load_kw	dc_capacity.critical_it_load_kw * dc_capacity.design_pue	kW	2
annual_facility_kwh_at_contract	dc_capacity.contracted_it_load_kw * dc_capacity.design_pue * 8760	kWh	0
annual_power_cost	dc_power.stated_annual_power_cost != null ? dc_power.stated_annual_power_cost : annual_facility_kwh_at_contract * dc_power.utility_rate_per_kwh	$	2
power_cost_per_kw_month	annual_power_cost / (dc_capacity.contracted_it_load_kw * 12)	$	2
annual_rent_revenue	dc_revenue.rent_per_kw_month * dc_capacity.contracted_it_load_kw * 12	$	2
blended_revenue_per_kw_month	(annual_rent_revenue + dc_revenue.interconnection_revenue_annual + dc_revenue.services_revenue_annual) / (dc_capacity.contracted_it_load_kw * 12)	$	2
rent_index	dc_revenue.rent_per_kw_month / dc_revenue.market_rent_per_kw_month	x	4

Two calcs reference standard sections, and they are the point of the RFC:

id	Formula	Unit	round_to
price_per_commissioned_kw	quick_metrics.purchase_price / dc_capacity.critical_it_load_kw	$	2
noi_per_commissioned_kw	noi_model.noi / dc_capacity.critical_it_load_kw	$	2

These are the per-unit metrics §X.2.4 withholds from the registry, supplied by the module instead. Whether module formulas may read standard sections (quick_metrics, noi_model) is settled at implementation: the hospitality module reads only its own sections, so the runtime's scope for standard sections is unproven. If the scope does not reach them, the implementation MUST NOT widen the runtime silently for one module; it stops and this RFC's §Unresolved gets the answer (a runtime change is its own small RFC, since it changes what every third-party manifest can read).

Validations

Each rule asserts what must be TRUE; it fires on false and stays silent on null — the RFC 0006 note 1 posture.

Code	Severity	Rule	Message
CC-MOD-DC-01	error	dc_capacity.design_pue >= 1	PUE cannot be below 1.0 — total facility power includes the IT load.
CC-MOD-DC-02	warning	dc_capacity.design_pue <= 1.6	Design PUE above 1.6 — legacy-grade efficiency; confirm cooling topology and the power pass-through terms.
CC-MOD-DC-03	error	dc_capacity.critical_it_load_kw <= dc_capacity.planned_it_load_kw	Commissioned load exceeds the planned build-out.
CC-MOD-DC-04	warning	dc_capacity.contracted_it_load_kw <= dc_capacity.critical_it_load_kw	Contracted load exceeds commissioned load — pre-leased phases; confirm the delivery schedule and any rent-commencement gaps.
CC-MOD-DC-05	warning	facility_load_kw <= dc_capacity.utility_feed_kw	Utility feed is below the facility load at design PUE — confirm the utility upgrade, its cost, and its date.
CC-MOD-DC-06	warning	dc_capacity.measured_pue == null || dc_capacity.measured_pue <= dc_capacity.design_pue * 1.15	Measured PUE more than 15% above design — the power pass-through economics are not what the design assumed.
CC-MOD-DC-07	warning	dc_revenue.market_rent_per_kw_month == null || rent_index >= 0.85	Contracted rent more than 15% below market — verify the comp set or the lease vintage.

CC-MOD-DC-04 is a warning and not an error because pre-leasing future phases is the normal hyperscale shape; the number is not wrong, it is a schedule question. CC-MOD-DC-05 likewise: utility upgrades pending are common and are a cost line, not a defect.

Example document

examples/Mesa-Gateway-Data-Center-Mesa-AZ.uwx.md — the Arizona series already has one document per builtin class; this is the first custom-class example, and it is deliberately imperfect the way the hospitality fixture is: contracted load above commissioned (a pre-leased phase 2) and a comp rent the contract runs under, so CC-MOD-DC-04 and CC-MOD-DC-07 both fire on one file. The modules: frontmatter entry is present, so MOD-DEPENDENCY-UNDECLARED does not fire.

Compatibility analysis

• Existing .uw.md files — no impact. Nothing changes for a builtin class; the enum is untouched (RFC 0003 note 1).
• Tier-1 readers without the module — a data-center document resolves degraded under industrial with MOD-FALLBACK-001. What such a reader shows: address, purchase price, NOI, debt, returns, the DCF — all correct. What it cannot show: any kW figure, and it will label price_per_sqft from the industrial layout if the document carries square footage, which for a powered shell is the misleading denominator this RFC exists to retire. The example document sets the property square footage to the building footprint and carries raised_floor_sf separately so that at least the number is not wrong, only unhelpful. This is the honest fallback and §X.2.3 already marks it degraded.
• Tier-2 editors — ordinary edit policies; the dc_* sections are ordinary sections.
• Tier-3 calc hosts — the module's calcs run through evaluateModuleCalculations; no core change unless the standard-section scope question (above) says otherwise, in which case the change is its own RFC.
• Tier-4 agent hosts — the §4.27-style prohibition on inventing terms applies by analogy: an agent MUST NOT invent a PUE, a redundancy topology, or a utility feed figure; the fields are null/absent until a source supplies them.
• Modules — manifest schema unchanged. This RFC is a use of the existing surface.

No spec change. Protocol and format versions do not move. The module is published as @uwmd/[email protected], the first module package after hospitality; the release ritual's package list grows by one.

Conformance impact

New in conformance/modules/runtime/ (beside the hospitality suite):

Scenario	Pins
02-data-center-fixture	The module against its own example: eleven calcs compute (or nine, if the standard-section scope question closes "no"); CC-MOD-DC-04 and CC-MOD-DC-07 fire; no error.
03-data-center-pue-below-one	design_pue: 0.85 → CC-MOD-DC-01 (error).
04-data-center-no-comp	market_rent_per_kw_month: null → CC-MOD-DC-07 silent, rent_index null.
05-data-center-required-section	dc_capacity removed → MOD-SECTION-MISSING.
06-data-center-as-industrial	The same file relabelled asset_class: industrial with no modules: — nothing from the module runs (the hospitality suite's "relabelled office" twin).
07-data-center-fallback	Module not loaded → degraded, MOD-FALLBACK-001, display name absent. This is the RFC 0003 resolution path on a product module, not the fixture one.

Existing fixtures unchanged, including conformance/modules/asset-classes/. docs/wiki/13-status.md gains a module row; ROADMAP.md gains the 0039 row.

Reference implementation

• Files: packages/uwmd-module-data-center/ (new; copy the hospitality package's package.json, tsconfig*.json and scripts/emit-manifest.mjs verbatim, then change names), the example document, the six runtime fixtures, conformance/modules/README.md table, docs/wiki/13-status.md, ROADMAP.md, the RFC index, CHANGELOG.md, VERSIONS.md (new package row), the release workflow's publish matrix (.github/workflows/release.yml) and verify-versions if it enumerates packages.
• API surface: the package's exports (DATA_CENTER_MODULE_ID, DATA_CENTER_MODULE_VERSION, DATA_CENTER_MANIFEST, DATA_CENTER_VIEW_MODELS). No change to @uwmd/core exports.
• Test plan: index.test.ts loads the manifest through the published loadModule / createModuleRegistry, resolves the example's class as custom with the module loaded and degraded without it, evaluates every calc against hand-worked figures (choose the example's numbers so every calc is an exact decimal: 10,000 kW commissioned, 12,500 kW planned, 11,000 kW contracted, design PUE 1.25, $150/kW/month), asserts each validation on a document built to fire it, and asserts the manifest loads with zero PROTO-MOD-* issues. The build must emit dist/manifest.json and the emitted file must load standalone.
• Effort: small-to-medium. The package is mechanical after hospitality; the standard-section scope question is the only place discovery can happen.

Implementation notes (deviations from the proposal)

Shipped 2026-09-09. The module is @uwmd/module-data-center; the example is examples/Mesa-Gateway-Data-Center-Mesa-AZ.uwx.md; the runtime scenarios are conformance/modules/runtime/06-…11-…. No spec change; protocol and format versions do not move.

1. Standard sections ARE in scope for a module formula — the one expected discovery closed "yes". evaluateModuleCalculations hands evaluateCalc the whole parsed file, and the §VIII.2 resolver walks frontmatter first (so quick_metrics.purchase_price resolves), then any section by id (so noi_model.* resolves), then prior_results. Nothing about the hospitality module's own-sections-only habit was a limit of the runtime; it was a limit of hospitality. Both per-unit calcs ship, pinned at $16,000/kW and $1,120/kW on the example, and no runtime RFC follows. The second unresolved question (a module-declared per-unit denominator) now has its evidence: the module's price_per_commissioned_kw sits beside an empty standard price_per_unit slot, exactly as §X.2.4 intends, and nothing so far argues for declares_size_intensive.

2. A declaring module was not scoped to its declared class — the unexpected discovery, and the only core change. ModuleManifest.asset_classes is typed to the builtin enum (PROTO-MOD-008 refuses a custom id there), and the runtime's applicability filter read only that field, treating its absence as "applies to every document". A module that declares a custom class and lists no builtin — this one — therefore ran against every file in the corpus and would have raised MOD-SECTION-MISSING for dc_capacity on every office deal. This is the composition gap the Motivation predicted ("required sections from the declaration versus required: true on the section … is unverified"), one level down. applicableModules in module-runtime.ts now treats declares_asset_classes[].id as classes the module applies to, alongside asset_classes; a module naming neither still applies to all. This is not the standard-section widening the RFC forbade — it changes when a class-declaring module runs, not what any manifest can read — and the prior behaviour was not one any host could have wanted. Unit test in module-runtime.test.ts; conformance 10-data-center-as-industrial pins it on the product module.

3. noi_model.net_operating_income, not noi_model.noi. The RFC named a field the format does not carry. The noi_model section's NOI field is net_operating_income (format §4, and every calc pack reads it so); the calc reads that.

4. Conformance scenarios are numbered 06–11, not 02–07. The RFC's table reused the hospitality suite's numbers; runtime/02-…05-… already exist. The scenarios are otherwise the RFC's six, in its order, and the runner now dispatches on expected.module across both packages and accepts the RFC 0003 resolution keys (expected_status, known_declarations, load_module: false) so the fallback scenario can be asserted without a second suite.

5. 07-data-center-pue-below-one fires four codes, not one. With design_pue: 0.85 and nothing else changed, the fixture's measured PUE of 1.32 is now far more than 15% above design, so CC-MOD-DC-06 fires alongside CC-MOD-DC-01, and DC-04/DC-07 fire as they do on the fixture. Pinned as such rather than editing a second field to silence a rule that is, in that scenario, correct.

6. requires_protocol: '>=2.5.0' for a different reason than stated. The RFC said the fixture carries dcf.returns.tax_basis; the example follows the industrial example's section set and carries no dcf. The pin stays at 2.5.0 because the module's findings are read alongside the RFC 0037 coverage channel and the RFC 0038 return basis, both of which entered at 2.5.0.

7. The package fixture and the example are one document. RFC 0006 note 6 kept the hospitality fixture separate from the public hotel example; here the example is the first custom-class example and the fixture is its byte-identical copy, with a test that fails if they drift. The conformance deal files are derived from it by one edit each.

8. Not touched, by instruction: CHANGELOG.md released blocks, VERSIONS.md existing rows, and .github/workflows/release.yml (a release branch is moving versions in parallel). VERSIONS.md gained the one new package row; verify-versions, verify-lockfile and verify-packages gained the one new entry each. The release workflow's publish matrix is left for the release branch — the module is unpublished, as hospitality is.

Alternatives considered

1. Add data_center to the builtin enum. Rejected: it is the status quo RFC 0003 exists to end, and it would need a spec bump, a size-intensive registry entry, an Excel layout and a calc pack — the full builtin cost — for one vertical. The module route is what the format promised; if it cannot carry a data center, that is the finding.
2. Extend the existing fixture module (com.example.datacenters) into the product. Rejected: the fixture's value is that its four documents are byte-identical and its manifest is minimal, so the resolution verdict is visibly about the reader. Growing it into a real module would blur that demonstration, and com.example is not a namespace anyone should ship under.
3. Model capacity in MW and rent in $/kW/month, as the market quotes them. Rejected: mixed units invite a factor-of-1000 error that no rule can catch after the fact. One unit (kW) throughout, with the view models free to display MW.
4. Carry the Uptime Institute tier (tier_iii, tier_iv) as a field. Deferred (§Unresolved): "Tier III" is a certification mark as well as a design vocabulary, and most facilities that market a tier are not certified. The redundancy topology is the fact; the tier is a claim about it.
5. Ship life sciences, manufactured housing and medical office in the same RFC. Rejected for the RFC 0006 reason: one module proves the custom-class contract; build the rest against the proven contract. Data centers go first because they stress §X.2.4 (the per-unit denominator) hardest.

Unresolved questions

• Standard-section scope in module formulas. Whether evaluateModuleCalculations resolves quick_metrics.purchase_price and noi_model.noi for a module calc. Settled 2026-09-09: yes, with no runtime change — see implementation note 1. Both per-unit calcs ship in 0.1.0.
• A module-declared per-unit denominator. If the two per-unit calcs work, a host still cannot show price_per_unit for a data-center file, because the §XIII registry does not know the class — so the standard per-unit slot stays empty while the module's own price_per_commissioned_kw sits beside it. That may be exactly right (§X.2.4's reasoning stands) or it may argue for a narrowly scoped declares_size_intensive on the declaration, gated to the declaring module's own class. Evidence first.
• Uptime tier as a field. See alternative 4. Proposed name if it lands later: stated_uptime_tier with certified: boolean, so the claim and the certification are separate facts.
• Power revenue under all_in billing. Under all-in or breakered billing the landlord earns a margin on power; dc_power.power_margin records it but no calc yet folds it into blended_revenue_per_kw_month because the mechanics differ by contract (margin on cost versus a fixed $/kW power charge). A power_revenue_annual field or calc is the likely follow-on once a document needs it.
• Excel. Custom classes get no Excel layout (§X.2.4). The hospitality module has one in @uwmd/excel because hospitality is a builtin; whether @uwmd/excel should accept a module-supplied layout is a separate question for whoever needs the workbook.

Prior art

• RFC 0003 (the declaration and resolution rules this exercises) and RFC 0006 (the module shape, the null-is-not-false rule, TS as manifest source of truth — all adopted unchanged).
• The Green Grid's PUE definition (total facility energy ÷ IT equipment energy) — the vocabulary source for design_pue / measured_pue; PUE ≥ 1 by construction is CC-MOD-DC-01.
• Uptime Institute Tier Standard: Topology — the vocabulary behind the redundancy enum, referenced without adopting the tier marks.
• Industry rent quoting convention ($/kW/month on contracted critical load; capacity in MW) — the unit decision in alternative 3.