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ValueGrid Specification

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ValueGrid

The Open Ledger of Property Intelligence

ValueGrid is an open-source property intelligence platform designed to create a transparent, verifiable, and publicly accessible foundation for understanding real estate value.

By combining advanced valuation models, environmental risk analysis, survey intelligence, regulatory datasets, and a National Property Ledger, ValueGrid provides a trusted infrastructure for appraisers, lenders, researchers, developers, and the public. The goal is to build a system that meets or exceeds the capabilities of proprietary platforms.

ValueGrid is created to support professional appraisal workflows, regulatory compliance, and public transparency across the entire property ecosystem.

Core Principles

Transparency

All valuation logic, models, and datasets are openly documented.

Verifiability

Property records include version history and cryptographic verification to detect tampering.

Professional Utility

The platform is designed to support real-world appraisal workflows and lending processes.

Public Accessibility

Non-sensitive data can be explored by anyone through a public interface.

Open Collaboration

Researchers, developers, appraisers, and surveyors can contribute improvements.

Key Features

Advanced Property Valuation Engine

ValueGrid provides transparent property valuation models that can be inspected, audited, and improved by the community.

Features include:

  • Comparable sales analysis
  • Price trend modeling
  • Neighborhood market analysis
  • Liquidity scoring
  • Valuation confidence scoring
  • Valuation explanation reports

National Property Ledger

The National Property Ledger serves as the authoritative historical record for property intelligence.

Each property record contains versioned data including:

  • Property attributes
  • Valuation history
  • Survey data
  • Environmental risk layers
  • Zoning information
  • Permit and improvement history

All updates are timestamped and traceable.

Environmental Risk Intelligence

ValueGrid integrates authoritative environmental and geospatial datasets that directly influence property value, insurability, safety, development potential, and long-term risk. Rather than relying solely on traditional valuation inputs, the platform incorporates environmental intelligence into every property record and valuation analysis.

Environmental datasets may include:

  • Flood maps and flood zone classifications
  • Base Flood Elevation (BFE)
  • Historical flood events
  • Storm surge risk
  • Sea level rise projections
  • Wildfire risk
  • Radon risk zones
  • Wetlands and protected lands
  • Coastal erosion zones
  • Landslide susceptibility
  • Earthquake hazard zones
  • Sinkhole susceptibility
  • Soil stability and erosion potential
  • Drought risk
  • Extreme heat exposure
  • Air quality trends
  • Water quality advisories
  • Hazardous waste and contaminated site proximity
  • Superfund site proximity
  • Brownfield locations
  • Dam inundation zones
  • Levee protection areas
  • Hurricane exposure
  • Tornado risk
  • Severe weather history
  • Lightning frequency
  • Snow and ice risk (where applicable)
Airport Safety & Aviation Intelligence

ValueGrid incorporates aviation-related datasets to help identify risks and development limitations associated with nearby airports.

Layers include:

  • Airport locations
  • Airport safety zones
  • Runway Protection Zones (RPZ)
  • Airport Overlay Districts
  • Noise contour maps
  • Height restriction areas
  • Flight approach and departure corridors
  • Avigation easements
  • Military airspace restrictions (where publicly available)
Environmental Risk Scoring

Environmental data is combined into a comprehensive property risk profile that can be used alongside valuation models.

Example factors include:

  • Flood exposure
  • Radon probability
  • Wildfire exposure
  • Airport noise impact
  • Coastal risk
  • Storm surge exposure
  • Environmental contamination proximity
  • Climate resilience

The resulting Environmental Risk Score provides a transparent summary of the property’s overall environmental profile while allowing users to review each contributing factor individually.

National Property Ledger Integration

Environmental intelligence becomes part of each property’s permanent record within the National Property Ledger.

Each property record may include:

  • Environmental Risk Score
  • Flood Zone Classification
  • Base Flood Elevation
  • Flood Insurance Requirement
  • Flood History
  • Storm Surge Risk
  • Wildfire Risk
  • Radon Zone
  • Radon Test History (when available)
  • Wetlands Indicator
  • Protected Land Indicator
  • Coastal Erosion Risk
  • Sinkhole Risk
  • Earthquake Hazard Zone
  • Soil Stability Rating
  • Airport Safety Zone Status
  • Runway Protection Zone Indicator
  • Airport Noise Zone
  • Height Restriction Zone
  • Environmental Dataset Version
  • Last Environmental Update Date
Benefits

Integrating environmental intelligence provides:

  • More accurate property valuations
  • Better lending and underwriting decisions
  • Improved insurance risk analysis
  • Greater transparency for buyers and sellers
  • Enhanced appraisal support
  • Development feasibility insights
  • Long-term climate and resilience awareness
  • Publicly verifiable environmental property intelligence

Survey Intelligence Engine

ValueGrid can ingest and analyze professional land surveys including:

  • Boundary surveys
  • ALTA/NSPS land title surveys
  • Topographic surveys
  • Subdivision plats
  • Elevation certificates

The system extracts:

  • Property boundary geometry
  • Easements
  • Encroachments
  • Building placement
  • Elevation information

This allows precise spatial analysis and improved valuation accuracy.

GIS Mapping System

A fully interactive geospatial map allows users to visualize property intelligence layers.

Property layers

  • Parcel boundaries
  • Building footprints
  • Survey geometry

Environmental layers

  • Flood maps
  • Radon zones
  • Wildfire risk

Infrastructure layers

  • Transportation corridors
  • Utility proximity
  • Broadband availability

Regulatory & Zoning Intelligence

ValueGrid integrates zoning and land-use rules to help analyze development potential.

Capabilities include:

  • Setback compliance analysis
  • Buildable area calculation
  • Zoning classification mapping
  • Land use restrictions

Market Analytics

ValueGrid analyzes housing markets at multiple geographic levels.

Features include:

  • Price trends
  • Supply and demand metrics
  • Market liquidity indicators
  • Housing affordability indexes

Public Verification Database

A publicly accessible property intelligence database allows users to explore verified information.

Publicly viewable data may include:

  • Parcel boundaries
  • Environmental risks
  • Valuation ranges
  • Survey status
  • Zoning classification
  • Market trends

Sensitive information such as personal financial data is excluded.

Cryptographic Record Integrity

Each property record update generates a cryptographic hash fingerprint.

This allows anyone to verify that records have not been altered after publication.

Example record metadata:

Record Version: 12
Last Updated: 2026-03-12
Change: Flood zone update
Source: FEMA
Hash: a84e6d7b91f2b42...

Example Property Record

Property ID: US-FL-025-00012345
Lot Size: 9,850 sq ft
Structure Size: 2,100 sq ft
Year Built: 1994
Estimated Value: $415,000
Confidence Score: 83%
Flood Zone: AE
Radon Risk: Moderate
Airport Noise Zone: Low
Last Survey: 2021
Buildable Area: 7,200 sq ft

Public API

Developers can access property intelligence through open APIs.

Example endpoints:

/property/{id}
/valuation/{id}
/environment/{id}
/survey/{id}
/market/{region}

Example response:

GET /valuation/US-FL-025-00012345

{
  "estimated_value": 415000,
  "confidence": 0.83,
  "valuation_range_low": 398000,
  "valuation_range_high": 432000
}

Use Cases

ValueGrid supports a wide range of applications.

Appraisers

Transparent valuation models and professional analysis tools.

Lenders

Improved risk analysis for mortgage underwriting.

Researchers

Large-scale property datasets for housing research.

Developers

Land intelligence for project feasibility analysis.

Public Users

Clear, accessible information about property conditions and risks.

Specification Branding License (SBL)

Standard

Optional

License & Notice Requirements

ValueGrid is released under the GNU Affero General Public License v3.0 or later (AGPL-3.0+).

By contributing to this project, you agree that your contributions will also be released under this license.

Please note the following:

  • All contributions must comply with the AGPL-3.0+ terms.
  • Under Section 7 of the license, all redistributions, forks, and derivative works must preserve attribution to Roxanne Ardary and roxanneardary.com.
  • ValueGrid specifications are free to use with attribution. A Specification Branding License can be negotiated upon request.
  • The project’s notice.md file tracks attribution requirements and contributor acknowledgments. Any update that adds new contributors or modifies attribution should also update notice.md.
  • When submitting a pull request, ensure that any new files maintain the attribution headers where applicable.
  • Network-deployed versions of this software must also remain fully AGPL-3.0+ compliant, including exposure of source code modifications when applicable under the license.

For full legal details, please refer to the AGPL-3.0+ license and the project’s notice.md file.

Notice – ValueGrid

Attribution Requirement: Under Section 7 of the AGPL 3.0+ license, all redistributions, forks, and derivative works, including network-deployed versions of this project, must provide attribution to Roxanne Ardary and roxanneardary.com.

Contributors

This file tracks contributors and their specific contributions to the project.

  • Roxanne Ardary, roxanneardary.com – March 12, 2026
    Created the repository for ValueGrid. Established the project vision and foundational structure for an open, verifiable property intelligence platform.
  • [Add other contributors here] – [Date]
    [Describe contribution in one sentence]

License – ValueGrid

This repository is licensed under the GNU Affero General Public License v3.0 or later (AGPL-3.0+).

Key Points

  • You are free to use, modify, and distribute the code.
  • All redistributions, forks, and derivative works or network-deployed versions must also be licensed under AGPL-3.0+ and provide attribution to Roxanne Ardary and roxanneardary.com as required under Section 7 of the license.
  • The software is provided “as is,” without warranty of any kind.

For the full license text, see GNU AGPL-3.0 License.

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