A digital twin is a virtual model of a real building or asset that stays in step with it, fed by live data from sensors and building systems. BIM gives the twin its starting point - the geometry and asset information handed over at the end of construction - and the twin adds the live data, so owners can monitor performance, predict failures and plan maintenance.
This blog post shares quite a lot! I first introduce digital twins, discuss the three main types, and then share my top 5 uses of Digital Twins with Building Information Models (BIM) and sensors in buildings. Let's get started!
Digital twins are computer models that represent real-world objects. They can be used for many purposes, including product development, manufacturing and maintenance.
Digital twins come in many shapes and sizes. In building operations, they can track the performance of building systems, predict the life cycle of equipment, plan maintenance, monitor occupancy patterns, adjust systems and improve building safety and security.
In this article, I'll concentrate on digital twins for buildings, but I'll also go through a few examples from other industries that use digital twins, and why they're valuable there. Let's get this digital twin party started!
1) Digital Twin Meaning
Many industries already use digital twins, but the idea is still fairly new in some fields (like construction), so let me first describe how I define digital twins and digital twin technology.
1.1) What is a Digital Twin?
Digital twins are digital representations of physical objects or systems. In other words, they are computer models that can simulate the behaviour of real-world objects.
These digital models mirror their real-world counterparts in near real time, giving organisations valuable insight into how their physical assets are working now, and how they might perform in the future.
The definition I use is the Digital Twin Consortium's: a digital twin is a virtual representation of real-world entities and processes, synchronised at a specified frequency and fidelity. The last part matters - a twin doesn't need every bolt, updated every second. It needs the right detail, often enough, for the decisions it supports.
1.2) What is Digital Twin technology?
In a nutshell, digital twin technology is the hardware and software used to manage the digital replica of a real-world object or system, combined with data about that object or system.
These tools use the physical and functional characteristics of the object or system to simulate its real-world behaviour and test different scenarios before they happen in real life.
Digital twins are constantly updated with data from their physical counterparts, so the two stay as similar as possible. Teams then use dashboards to monitor the replica in real time, make predictions about the future and act on what they see - sometimes automatically!
1.3) Digital Twin Benefits
Digital twins can be used for a variety of purposes, such as:
- Understanding how a physical object will respond to specific conditions
- Planning maintenance or repairs
- Tracking the performance of a physical thing over time
- Predicting the life cycle of a physical object
- and many more that I describe in more detail below...
1.4) Digital twin vs BIM - what's the difference?
People often use the two words for the same thing, but a BIM model and a digital twin do different jobs:
| BIM model | Digital twin | |
|---|---|---|
| What it is | A shared model of the asset as designed and built | A live model of the asset as it runs |
| Data | Geometry and properties, updated at each milestone | Asset data plus live feeds from sensors, building management and maintenance systems |
| When | Design and construction, handed over at completion | Operation, for the life of the asset |
| Used by | Design and construction teams | Owners, operators and facility managers |
| The question it answers | Will it fit, and will it work? | How is it performing, and what will fail next? |
So a BIM model isn't a digital twin on its own, but a good one is the best place to start. Under ISO 19650, the information an owner needs to run the asset is set out in the asset information requirements (AIR), delivered by the project team and kept as the asset information model (AIM). Connect that to live data and you have the bones of a twin. The free lesson on asset information requirements (AIR) explains how to write them.
2) A brief history of Digital Twins
Digital Twin Origin: the idea of a twin goes back to the Apollo space program, when NASA kept simulators on the ground that mirrored the spacecraft in space. They weren't digital yet, but when Apollo 13 got into trouble in 1970, engineers used them to work out how to get the crew home.
Since then, digital twins have been used in many industries, including healthcare, automotive manufacturing, and oil and gas exploration. Here is a brief timeline of digital twins in history:
- 1960s-70s - NASA uses mirrored simulators of its spacecraft to test and solve problems on the ground
- 1970s - Oil and gas companies begin using computer models to explore for new reserves
- 1980s - Automotive companies use digital models to design and test new vehicles
- 1991 - The idea of software that mirrors the real world is described in the book Mirror Worlds, by David Gelernter
- 2000s - Healthcare organisations begin using digital models to plan patient care
- 2002 - Michael Grieves applies the idea of a virtual model linked to a physical product in the manufacturing industry
- 2010 - NASA creates digital simulations of spacecraft for testing, and the term "digital twin" is credited to John Vickers of NASA
- 2017 - Gartner names digital twins as one of the top 10 strategic technology trends
- 2018 - The Centre for Digital Built Britain publishes the Gemini Principles for digital twins of the built environment
- 2020 - The Digital Twin Consortium forms to drive awareness, adoption, interoperability and development of digital twin technology
- 2021 - Some of the world's largest owners, like Amazon, start planning and contracting for digital twins using Plannerly
3) The Three Types of Digital Twin
Let's look at the three most common forms of digital twin: the prototype, the instance and the aggregate. They have a lot in common, but each has its uses. For a building, the design model is the prototype, the twin of the finished building is the instance, and a campus or portfolio of connected twins is the aggregate.
3.1 Digital Twin Prototype (DTP)
A digital twin prototype, or DTP, is a digital representation of a physical counterpart before the physical product is made.
The DTP simulates real-world conditions, so organisations can see how the physical counterpart will perform without spending money making it. DTPs can assess everything from components and systems to entire buildings (using everything from BIM, from sketch to digital twin BIM!) and infrastructure projects.
Advantages:
- Lets you test different scenarios before committing to a physical product
- Helps you understand how the physical product will respond to specific conditions
Disadvantages:
- Can be expensive to create
- Needs high levels of accuracy and detail
Applications:
- Automotive design and testing
- Consumer products
A digital prototype of a car before it is manufactured allows different conditions, such as wind, weather or terrain, to be tested, so the vehicle can be designed to perform well in them.
3.2 Digital Twin Instance (DTI)
A digital twin instance, or DTI, is a digital replica of one real-world physical object or system, used to test how it will work in different or new situations.
DTIs are built from data collected from sensors and other sources, and they can monitor, simulate and optimise the performance of the physical counterpart.
Advantages:
- Can test how a product will work in different situations
- Helps you understand how the physical counterpart will perform
Disadvantages:
- Needs accurate and up-to-date data
Applications:
- Industrial plant maintenance
- Healthcare technology
- Smart buildings
For example, a DTI of an industrial plant could track production levels, identify bottlenecks and find ways to improve efficiency.
DTIs can also predict how a physical system will respond to changing conditions, such as weather events or traffic patterns. By understanding how the system is likely to behave, engineers can make better decisions about operating and maintaining it.
3.3 Digital Twin Aggregate (DTA)
A digital twin aggregate (DTA) - sometimes called a connected digital twin - is a group of digital twin instances linked together for real-time data sharing and analysis. DTAs are often used to monitor large, complex systems like power grids or transport networks.
Advantages:
- Can monitor large, complex systems in real time
- Helps you understand how different parts of a system are performing
Disadvantages:
- Needs accurate and up-to-date data from every digital twin instance
Applications:
- Power grid monitoring
- Transport network monitoring
- Smart city planning
For example, a DTA of the power grid could monitor electricity use across a city, so utilities can make better decisions about where to invest in new infrastructure and how to price their services.
DTAs can also help manage transport networks, such as railways or highways. By understanding how traffic flows, authorities can make better decisions about where to build new roads or improve existing ones.
4) Industries using Digital Twins
So we've talked about definitions and types of twin; now let's briefly look at five examples of how different industries actually use digital twins:
4.1) Digital twins used in manufacturing
In manufacturing, digital twins are virtual models of products, used for design and analysis as well as production planning and quality control. Examples could be my mobile phone, or a new smart lock I might want to fit on my front door. These twins simulate the product's behaviour and predict how it will perform in future.
4.2) Digital twins used in Engineering
Engineers use these models to test new designs before building them, and to make sure the design meets safety standards. They also use them to visualise the final product so they can see what it will look like.
For a wind farm, for example, a twin can help establish where it's best sited, which direction the turbines should face and how long they're expected to run before maintenance.
Engineering digital twins are also virtual models of whole systems, used for design and analysis as well as performance monitoring and fault detection.
4.3) Digital twins used in Healthcare
In healthcare, digital twins are used to create virtual models of patients. Yes, that's crazy. A virtual model of the human body!
These models can be used for personal diagnosis, treatment planning and even surgery rehearsal. A patient model can hold all the medical data about that patient, so doctors can see all the records at once rather than searching through multiple files.
Digital twins also help when developing new medical devices: a company can use a twin to test how a device interacts with human tissue.
4.4) Digital twins used in the Automotive Industry
In the automotive industry, digital twins are virtual models of vehicles, used for design and analysis as well as manufacturing and assembly planning.
An automotive digital twin holds all the relevant data about a car, so engineers can test different designs before building real ones - and car makers save the time and money they'd otherwise spend on prototypes that won't work.
4.5) Digital twin BIMs used in AECO (Architecture, Engineering, Construction, and Operations)
The most notable application of digital twins for me is using Building Information Modeling (BIM) for buildings.
The AECO industry uses BIM software to create virtual models for architecture, structure, mechanical, plumbing and electrical systems. These models are used for design simulation, construction planning, facility management and even sales.
It's pretty cool that a digital twin BIM can simulate a building project's environment before it begins and then support the whole life of the building's operation. Architects, for example, use digital twins to test new designs before construction teams start building them, by creating a 3D digital version of the building and testing different configurations.
Below (in part 6), I describe five ways digital twins and BIM are being used in AECO, but perhaps the biggest benefit is that digital twins can significantly reduce risk and improve decision-making across the whole AECO sector. With so much at stake, it's important that the construction industry gets on board and starts reaping the benefits.
5) Standards for Digital Twins
The work started by CDBB and the Digital Twin Consortium is encouraging. It's still early days for digital twin standards, but some great ideas are brewing.
In general, digital twins should:
- be accurate representations of the physical world
- be updated in real time
- be accessible to authorised users
- be secure
In order to:
- aid the operation and maintenance of existing assets and systems
- support the planning, design and construction of new assets and systems
- improve communication between project stakeholders
- help manage construction projects
- reduce costs and improve efficiency
- help with the handover of assets from construction to operations
- monitor and manage the performance of assets and systems during their working life
And result in these benefits:
- reduced risk and better decision-making
- increased efficiency and productivity
- improved safety and less downtime
- a better experience for the people who use the asset
5.1) Gemini Principles report from the Centre for Digital Built Britain (CDBB)
The Centre for Digital Built Britain released the Gemini Principles report in December 2018 to set out the concepts and principles of digital twins for the built environment. Its nine principles sit under three headings: purpose (public good, value creation, insight), trust (security, openness, quality) and function (federation, curation, evolution).
The report made several recommendations, including that:
- digital twins should be embedded in government policy and regulation
- standards and guidance should be developed for the use of digital twins
- funding should be made available to support the use of digital twins
The report said digital twins have the potential to transform the AECO sector and deliver significant benefits to society. Much work is still needed to realise that potential, but the report gives a clear roadmap. CDBB finished its work in 2022, and the Gemini Principles are still the reference point most people start from.
Download the report: The Gemini Principles - BIM and digital twins (PDF) (opens in a new tab)
5.2) Digital Twin Consortium (DTC)
Other movements supporting digital twins include the Digital Twin Consortium (DTC), which is helping our industry align everything from definitions to standards and guidance. The DTC has also published guidance to help healthcare organisations improve clinical care with digital health platforms, and runs regular webinars on practical implementation topics.
On 3 December 2020, to establish a foundation for future progress, the Digital Twin Consortium released the definition I quoted in part 1:
In 2022, the DTC also released the Digital Twin Capabilities Periodic Table (opens in a new tab) (an excellent guide by Pieter van Schalkwyk). It's aimed at organisations that want to design, develop, deploy and operate digital twins based on the capabilities their use cases need, rather than on the features of a particular technology. The main focus is on how to get started.
Download the guide: DTC Capabilities Periodic Table user guide (PDF) (opens in a new tab)
5.3) ISO 19650 and the asset information model
ISO 19650 isn't a digital twin standard, but it's where a building's twin gets its data. The owner's organisational information requirements (OIR) say what decisions the organisation needs to make; the asset information requirements (AIR) say which assets and properties it needs to make them; the project delivers that information; and the asset information model (AIM) holds it for the operational phase, which ISO 19650-3 covers. Our free lessons on the OIR and the AIR walk through both, and the AIR slides (PDF) (opens in a new tab) are free to download.
6) Digital Twin Use Cases in AEC - Five Ways Digital Twins and BIM are being used in AECO
You can use simple architectural and construction drawings to understand a building, but digital twins can be used in so many more ways. Here are some examples:
- Performance of building systems, to find potential issues before they cause problems
- Predict the life cycle of building systems and plan maintenance
- Create "virtual prototypes" of new buildings or renovations to test feasibility and optimise designs
- Monitor occupancy patterns and adjust heating, cooling and lighting
- Improve safety and security in buildings by tracking people and equipment movements
Let's take a look at each one:
6.1) Performance of building systems
Digital twins with BIM can monitor the performance of building systems. By connecting sensors to a digital model of the building, engineers can find potential issues before they cause problems. For example, if a sensor detects a water leak, the twin shows where the leak is, which pipe and valve serve it, and how to fix it.
6.2) Predict the project lifecycle of building systems and plan maintenance
Digital twins can also predict the life cycle of building systems so maintenance can be planned accordingly. By understanding how a system is used, the twin helps engineers decide when to service it. For example, if a twin predicts that a piece of equipment will need replacing in five years, the engineer can plan and budget for the replacement now.
6.3) Feasibility of using virtual prototyping to optimise designs
Digital twins can create "virtual prototypes" of new buildings or renovations. By modelling the proposed design, architects can test the project's feasibility and optimise it. For example, an architect designing a new office building can use a digital twin to test how it will respond to different weather conditions.
6.4) Monitor occupancy and adjust systems
Digital twins can monitor occupancy patterns and adjust heating, cooling and lighting accordingly. By understanding how people use a building, they help building managers save energy and improve comfort. For example, if a twin shows a room is only occupied for an hour a day, its heating and cooling can be turned down for the rest of the day.
6.5) Improve safety and security in buildings
Digital twins can also improve safety and security. By tracking the movement of people and equipment, they help building managers spot potential hazards and respond to emergencies. For example, if a twin shows a person in a dangerous area of the building, the security system can be alerted to protect them. More on this in how BIM affects health and safety.
Digital twins are a powerful tool with many applications, and by understanding how they work, engineers and architects can use them to improve the performance of buildings. What do you think? Are digital twins a valuable tool for building design and operations?
7) What you should do now
Digital twins are a versatile tool that can be used in almost any industry - now it's up to you to plan how you and your organisation will benefit.
When you plan your digital transformation, consider how digital twins might reduce risk, improve decision-making and deliver the main benefits for your company. Start with the basic questions: what exactly is a digital twin, why should we care, and what's the best way to get started?
Here are some questions you can use in your organisation to get people thinking about digital twins:
How to get from a BIM model to a digital twin
The sensors and dashboards get the attention, but most twins succeed or fail on the data handed over at the end of the project. Five steps:
- Start with the decisions. What should the twin help you decide - maintenance, energy, space? That's your organisational information requirements.
- Ask for the asset data precisely. Which assets, which properties, in what format (COBie is common). Write it into the AIR and the contracts, not a wish list - see how to write OIR, AIR and EIR.
- Check every model before you accept it. Turn the requirements into an IDS file the authors can check against, and check each delivered model against the same requirements - see model checking with IDS and Plannerly's Verify module.
- Hand over a clean asset information model and load it into your maintenance and facility management systems. The free lesson on BIM verification and COBie handover shows the whole step.
- Connect the live data - sensors, building management, work orders - and start with one of the five uses above, not all of them.
Projects usually fall down at steps 2 and 3: the data asked for was vague, and nobody checked it arrived. Get those right and the twin has something to stand on.
To help you, I also wrote some simple answers to the most common questions I've had to answer about digital twins. I hope they help you in your implementation!
I blog for the Five BIM Bloggers series, where every week we share different perspectives on important BIM topics. To hear our views first, join Plannerly free or browse the Plannerly BIM blog.
