February 2021

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Quantum: The Digital Twin Standard for Buildings

Quantum is the industry’s first true ontology: an existential definition of properties, behaviors, intent, and interactions between building objects.
Troy Harvey

Troy Harvey,

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Quantum is a new digital twin standard for buildings, developed through a partnership between PassiveLogic, the U.S. Department of Energy, and industry partners. Quantum is the industry’s first true ontology: an existential definition of properties, behaviors, intent, and interactions between building objects.

Ontology-based digital twins are a requirement for autonomous building systems, self-assembling data, unified building APIs, and smart city energy networks — filling a huge gap in the market that has until now been largely focused on the retrospective effort of tagging and topology semantics, or creating BIM-like digital twin middleware. The Quantum standard provides a complete building definition, allowing the description of everything in and around buildings including thermal zone connectivity, proxemics, systems, equipment and IoT component models, IT and data network structures, weather models, and occupant models. It can also embed the data time series for these features, for both histories and predictive futures.

Why a New Standard?
Why do we need a new standard? Previous standards have focused on communicating point labeling, or the post-hoc descriptions of equipment linkages. While standards like Haystack provide tagging, Brick adds taxonomy, and ASHRAE 223p is a formalization of the former concepts — these primarily define human-to-machine communication, but have limited utility in machine-to-machine and machine-to-self contexts. As such they are primarily what we'd call semantic standards.


Previously proposed digital twin prototypes have had many of the same limitations. Typically designed to be generalizations of BIM semantics or generalized semantics for data pools, they are still limited by their low descriptive power.

The study of semantics is primarily concerned with labeling or defining the formal names of things. But it does not answer the questions: “Who am I?” or “What do I do?” These questions are the province of ontologies, not semantics. An ontology describes the fundamental nature of being, while semantics deal in descriptive labeling. And while an ontology can certainly be serialized into a semantic, a semantic doesn’t have the framework for expressing an ontology — and exists at the wrong layer in the stack to retroactively bolt one on. Yet, evolving market needs and technological advances require more descriptive power and use cases that emerge from machine-to-self capability.

Equipment Existentialism
Quantum is concerned with “What it is”, whereas semantic tagging is "How to say it” in a protocol or disk format. For example a “chair" is merely tagged as “chair” in English, but carries no inherent meaning. It fundamentally is not a chair, but a gravity resistor that keeps your butt from hitting the ground (gravi-keister-limitor). You can translate the fundamental nature of a “gravi-keister-limitor” into many languages and protocols, but its existential purpose never changes. More compellingly, by defining object existentials using their underlying physics (RForce = Gravity x Massbutt) we can compute meaningful purpose in context to its application or control. After all, physics is the most Meta standard for defining “What”, “How”, and “Why”. So while semantics and existentials are both useful components of digital twins, it is important to understand the difference as we set the course for the next generation of control and the emergence of autonomous building systems.


Actors, Quanta, and Behaviors… Oh My!
In the context of building digital twins, Quantum represents a fully descriptive language for systems, buildings, and the interconnections between them. It inherits its name from quantum physics, the study of matter and energy at its most fundamental level. Similarly, Quantum Digital Twins describe buildings, automation, and IoT using the fundamental language of physics. 

In Quantum, the defining physics is classified into meaningful containers. These containers are easily expressed as small components of purpose. And unlike the environments of EnergyPlus or Modelica, where physics is an unstructured bag-of-math, here physics is definitional, composed, and purposeful. It defines the notion of what something is, how it does what it does, and the roles and behaviors of building components within a system. 

Quantum introduces new concepts of actor types, quanta (the currency of interchange), behaviors, computed properties, and observed properties. In its entirety a Quantum Digital Twin is an object’s description, computable AI with introspectable properties, and a transmittable format. These concepts are crucial in defining autonomous systems, generalized model based control, and self-describing equipment that communicates and is acted upon in real time.

Backwards Compatibility
While Quantum can be used as a complete stand-alone standard, it is also designed for backwards compatibility. Through a process called semantic lowering, it can consume tagging standards like Haystack, or protocol application layer standards like BACnet, KNX, or Zigbee. Similarly it can import or export Brick, EnergyPlus, GBXML, and IFC formats. Each of these are lossy exports, covering only a fraction of the descriptive power of Quantum — but it provides bridging and tooling for other standards where PassiveLogic’s Autonomy Studio software can serve as a front-end. 

Why Quantum Matters 
Quantum is not just an automation data standard, it enables a paradigm shift in our approach to buildings. It provides a continuous digital asset from architecture through implementation and into maintenance — enabling an integrated workflow for the automation market, including hand-offs from engineers to field technicians. Quantum provides deep context for building data, and automatically structures this data into information, generates inferences, and enables autonomous controls to make actionable decisions at the edge. 

Quantum contextualizes meaning and intent before a project even hits the ground, and maintains that information structure, data fusion, and data graphs throughout its life-cycle. This diverges from the market approach where you stream low-value data, add post-hoc labeling, and hope through data mining to eventually strike gold and find value.

Making Life Simple 
Perhaps most importantly, Quantum simplifies project workflow. Because digital twins are expressible in tangible visual terms, they are amenable to graphical UIs and generative CAD tools.

At PassiveLogic we’ve built the first integrated development environment (IDE), Autonomy Studio, around the Quantum standard. Autonomy Studio’s design process replaces the traditional CAD workflow that merely generates paper plans. Using digital twin components it instead generates the controls schema from the system drawings, validates the design against the physics, generates the controls system topology, commissions the building, and automatically classifies the analytics, all while preserving the building’s designed intent. No integration or bridging effort required.

The Future
Buildings are the largest controlled infrastructure in the world economy, yet our automation systems are still not equipped with the full picture of what they are supposed to control. Quantum Digital Twins can address this gap by providing the automation platform with a complete picture of the system that can self-introspect, and solve for the ideal optimization control path in real-time.

Quantum opens up significantly improved building operation that includes greater energy
efficiency, pinpoint occupant comfort, continuous automated commissioning, predictive maintenance and alerts, and longer lasting equipment. In addition, our industry involves many stakeholders on every project, and this standard allows stronger communication and the preservation of design intent throughout the life-cycle, preventing information loss.

Stay tuned for part 2 of this series where we’ll discuss how Quantum IS the AI. Part 3 will go into Autonomy Studio in detail.


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