Since its inception, Project Haystack has been known primarily as a tagging standard—the method used across the smart building industry to describe points and equipment using metadata. However, with the emergence of Haystack 5 and the introduction of Xeto, that definition is no longer accurate.
Today, Haystack has evolved from simple tagging into a full semantic modeling framework, or ontology, and the BENEFIT Project undertaken by Project Haystack and it’s partners has delivered Xeto, the engine that expresses, formalizes, validates, and operationalizes those semantics across devices, buildings, portfolios, and applications. Together, Haystack 5 Xeto represent something much bigger, it is a universal, open, machine-readable language for buildings. And it is here now!
What Haystack 5 Really Is
Haystack 5 is the latest evolution of the Haystack standard—a comprehensive semantic data model that describes in a formal, standardized, and validated way:
- What building assets are
- How they relate
- How they behave
- How they interact
- How data should be interpreted
It includes:
—A rich, extensible ontology: HVAC, energy, lighting, metering, IEQ, electrical systems, IoT sensors, and more.
—A graph-based modeling foundation: Describing systems in terms of their relationships—not just labels.
—A universal vocabulary of tags: For consistent meaning across platforms, vendors, and applications.
—A formal semantic structure: Meaningful models that analytics, digital twins, AI, and data platforms can rely on.
But Haystack 5 does something else—it sets the meaning, while Xeto sets the structure and enforcement.
Where Xeto Fits: Bringing Haystack Semantics to Life
Xeto is the modern semantic schema language that operationalizes Haystack 5. It provides the mechanisms to define:
- Official semantic models in a repository style system
- Equipment profiles defined by OEMs
- System definitions as agreed on by Subject Matter Experts
- Validation rules according to formalized grammer
- Inheritance and relationships to leverage existing work
- Portfolio-scale standardization to reduce labour and cost for deployment
With Xeto, you don’t just tag a VAV box. You define a VAV type, its required points, its potential relationships, its dependencies, and its expected behaviors—all in a machine-readable schema. In short, Haystack 5 defines the semantics.
Xeto defines the models, rules, and structure that bring those semantics into reality. Xeto is the missing link the industry has been waiting for a true, fit-for-purpose, modeling language built on open standards and aligned with modern digital building architectures.
Moving Beyond Tagging: The Haystack 5 Xeto Breakthrough
Tagging alone was never enough for the future. AI, analytics, digital twins, and next-generation BAS systems require structured semantics, not loose descriptions. Haystack 5 Xeto deliver this by moving the industry forwards, from:
- Metadata → Meaning: Understanding what something is and how it works.
- Points → Systems: Modeling equipment, relationships, loops, and full system hierarchies.
- Manual → Automated Modeling: Xeto allows repeatable, validated, auto-generatable models.
- Descriptions → Validation: Schemas ensure data quality, correctness, and consistency across a portfolio.
- Edge → Enterprise Scale: Semantic continuity from controller → device → building → portfolio → cloud.
- Open Tags → Open Models: Vendor-neutral models that anyone can adopt, extend, or integrate with.
How Haystack 5 Xeto Enable What the Industry Needs Now
Today’s buildings rely on:
- AI-driven insights
- Predictive maintenance
- Digital twins
- FDD and analytics
- Cloud-edge synchronization
- Cross-vendor data normalization
- Enterprise data integration
- Composable OT architectures
None of these can be powered by tags alone. They require semantic depth, model fidelity, and automated consistency—enabled only when Haystack 5 and Xeto are used together. With Haystack 5 you know what your assets mean. With Xeto, you know how they must be structured, built, validated, governed, and delivered.
Real-World Impact: What Haystack 5 Xeto Deliver
- AI-ready structures: Machine reasoning requires clear semantics and validated models—Xeto enforces both.
- Portfolio-wide standardization: No more reinventing models for every building; schemas are reusable across thousands.
- Digital twins that reflect real systems: Relationships and system behaviors are inherently defined.
- Automated workflows and data pipelines: Consistent schemas enable auto-tagging, auto-normalization, and auto-model assembly.
- Cross-platform interoperability: Analytics, visualization tools, IDLs, and digital twins all consume the same schema.
- Dramatically reduced integration labor: Schemas eliminate the guesswork and manual effort integrators have lived with for decades.
Haystack 5 Xeto Are the New Semantic Foundation of OT Data Management
Every major building data challenge—interoperability, normalization, duplication, inconsistency, and lack of context—comes down to meaning and structure.
Haystack 5 provides the meaning. Xeto provides the structure. Together, they create a universal, open semantic layer that sits beneath:
- OT data management platforms
- Independent data layers (IDLs)
- Digital twins
- Analytics and FDD platforms
- AI applications
- Edge controllers
- Cloud systems
- Enterprise integrations
This is the architecture modern buildings demand.
Summary
Haystack 5 Is More Than Tagging—It’s the Semantic Core That Xeto turns tnto an operational reality. Tagging was the beginning. Haystack 5 is the meaning layer. Xeto is the modeling and validation engine. Together, they enable buildings to:
- Understand themselves
- Model themselves
- Document themselves
- Communicate meaningfully
- Scale consistently
- Feed AI-ready data to any platform
Haystack 5 is the “what.” Xeto is the “how.” And together, they define ready for intelligent buildings.” This is the future of building semantics. the “why we’re finally
Marc Petock
Project Haystack Board of Directors
Vice President, Chief Marketing & Communications Officer, Lynxspring