Trial / Demo
The concept of the Digital Twin has seen a surge in popularity in recent years. So, it’s no surprise that our exclusive Defining Digital Twins session, held in partnership with the B1M, sparked significant interest. With nearly 100 questions submitted, addressing each one individually wasn’t feasible. However, common recurring themes emerged: with many inquiries centred around Data & Metering strategies for Digital Twin development.
To tackle these questions, we turned to Mark Gifford, our Associate Director of Energy Services and resident expert in data analytics and metering strategies. In this two-part Q&A series, he addresses several of the key questions raised during last month’s webinar.
Read on for part one, where Mark shares invaluable advice on current industry guidance, metering and sub-metering considerations, and the role of digital twins in facilities management.
Do you think TM39 (Metering) is prescriptive/detailed enough on the levels of sub-metering required in new buildings. Are current levels of sub-metering in building sufficient to provide the information needed for input into digital twins?
CIBSE’s TM39 provides some useful guidance on metering, and in combination with TM54’s lays a good foundation for developing a post-occupancy analysis framework. This facilitates comparative analysis back to Design stage energy predictions but in practice, there’s often still a gap between ambitious design stage guidance and what is practically implemented in reality due to a wide range of challenges.
For instance, while TM39 addresses some of the challenges around specifying meters, it lacks fully detailed specifications. It’s like setting out to buy a new car. Do you need a Petrol, Diesel or Electric? Manual or Automatic gearbox? Red, Blue, Silver other colour? Manufacturer / Model?
The design and specification of building energy metering infrastructure can be like this too. Simply specifying ‘Metering’ is not enough and can leave a lot of room for mismatches between the final installed metering solution vs the original design expectation. Pulsed output vs ModBus? Turbine, Diaphragm or Ultrasonic meters? Manufacturer / Model? Even when clients specify the right meters, contractors often make substitutions to cut costs via Value Engineering, impacting data quality and ease of interoperability. Plus, insufficient install and commissioning means that even well specified and selected meters might not be installed fully to manufacturer guidance, creating further logistical challenges.
Data granularity is another challenge. Highly detailed, room-by-room metering can provide unique insights but can easily overwhelm with too much data, making meaningful analysis difficult. A design aspect that is often missed is the suitable sizing of a Meter vs the line size and expected load magnitude that it’s fitted on. It’s like a 1, 10 vs 100 problem where it’s all too common to find a count size in the 100 range trying to monitor lower value changes in the 1-10 range (or vice-versa). Finding the ‘Goldilocks’ balance is key —not too little, but also not so much that it becomes unmanageable.
Metering setups also vary widely by building type and age. A modern commercial building may have extensive sub-metering infrastructure, while older buildings may not. Often, meters are not strategically placed, leaving high-energy systems, like HVAC, unmetered while low-use areas, like lifts and sprinkler systems, are over-metered, limiting data relevance.
The ideal metering strategy involves strategic placement of sub-meters in the right locations in order to provide accurate coverage of the main % components of building energy loads. This is where the energy modelling potential of a Digital Twin solution can offer unique capability. The Digital Twin is developed as a virtual replica of the building and operational energy/HVAC systems. Virtual sub-metering can then be used to better understand and predict % energy loads and physical meters can then be strategically located within the design solution to monitor these identified priority load profiles.
Do you think there’s a knowledge gap in metering strategy guidance for enabling in-use operational energy modelling? Given that TM39 (2009) and TM31 (2006) are outdated, and Building Regulations require 90% energy metering by end use but lack guidance on implementation? Could a more detailed metering strategy offer added value to building owners?
The Smart Building landscape is evolving rapidly and extends well beyond the traditional Mechanical and Electrical engineering disciplines and fields of expertise. IT Networking and Cyber Security have become critical elements too and traditional knowledge bases, even the Building Regulation Frameworks themselves, can struggle to find the identity they need in the complex project and corporate environments we face today.
Another significant challenge is the disconnect between Design and Facility Management (FM) teams, who often operate in silos and lack an understanding of each other’s priorities. Misalignment of this nature can result in a significant Performance Gap and often even the base infrastructure needed to manage the operational needs of the building effectively from an FM perspective can be lacking e.g. FM Manager is unable to access the BMS at a sufficient level of access, trend logging on required strategic monitoring points has not been configured etc.
Addressing these issues requires a more holistic approach to in-use operational energy modelling. Updated guidance is essential, but equally critical is the development of accurate energy profiles derived from real-world data rather than default National Calculation Methodology (NCM) profiles, which often fail to reflect actual building usage.
For effective operational modelling, a guiding framework—or "North Star"—is needed to ensure alignment. This would encourage modellers to base time schedules and profiles on observed data rather than assumptions. By adopting such an approach, building owners would gain a deeper understanding of their energy usage, unlocking the full potential of a well-defined metering strategy.
How "Smart" does a building have to be at the start to allow robust assessment? Does a simple BEMS connection suffice or would you add existing monitoring equipment? I am thinking in terms of aged estates for University buildings, where buildings are 100 years plus?
To start assessing a building's performance, having half-hourly data from the main incoming meter is a great first step. It’s often available—even if the facilities team isn’t aware they have access to it. Half-hourly data moves you from monthly utility bills to a much higher resolution, enabling a more robust analysis right away.
If half-hourly data alone doesn’t give enough insight, the next step is to look at sub-metering. In many buildings from the past 20 years, there’s often some existing sub-metering infrastructure in place due to Part L regulations or BREEAM requirements (2006+). Older buildings (pre-2000) may lack these sub-meters, so you may need to add them or re-commission any legacy meters that aren’t fully connected to a BEMS.
For older buildings, starting with half-hourly data and gradually upgrading to sub-metering if needed should provide a strong basis for assessment without overhauling the whole system.
Again, the level of data required really depends on the end-use case of the digital twin. Ensuring you have a clear vision of the use case for your digital twin is the first and foremost thing you should consider, and then you can look at what level of data is required to achieve this. Download our free guide: The Practicalities of Creating Performance Digital Twins, to understand the different levels of data granularity you can achieve depending on your end-use requirements.
How has the use and uptake of Digital Twin technology impacted within facilities management?
To date there have been challenges in using energy models in the building operational phase. In 2023 we commissioned a survey as part of a research paper exploring the appetite, benefits and challenges of using Digital Twins to facilitate whole-life performance modelling. The survey gathered insights from a number of AEC practitioners (consultants) and building owners, occupiers and facilities managers (clients) to understand how energy models were currently being used and shared between built environment project stakeholders, and the challenges and benefits of using these models from design through into the operational phase of buildings. The results revealed that while 90% of consultants and 89% of clients see the value in utilising Energy Models in operation to achieve net-zero goals, there are some major barriers (see below chart).
AEC consultants see the main barriers to using energy models in operation, as lack of understanding by clients (63%), cost to implement (62%), and accessibility of models (54%). Hence why we have developed IES Live (a cloud-based platform that connects near real-time operational building performance data to your digital twin) to act as that bridge between AEC consultants and their clients. IES Live increases model value & client understanding of building performance, and prevents energy models becoming out of date and keeps them accessible. IES Live delivers the value of digital twins to facilities managers and energy managers in a way that they can gather the information needed for their day-to-day jobs, but also support sustainability teams in delivering capital projects that deliver on net-zero targets.
The University of Liverpool is a great example of this – IES Live was installed on a campus building, allowing advanced energy and carbon management of the building, as well as live tracking and verification of savings made from an HVAC refurbishment undertaken on the building.
Read the full case study.
About Mark
Mark specialises in Energy Services, Monitoring Based Commissioning, Data Analytics and Measurement & Verification (M&V), and leads a specialist team of engineering consultants whose primary focus is Building Performance Optimisation projects via integration with smart metering and BMS controls data.
Contact our team for more information or visit our website.
Defining the Digital Twin
Missed our Defining the Digital Twin Webinar in partnership with the B1M? View the on-demand version to hear what industry experts had to say.
Want to discover the capability of IES' suite of Digital Twin technology? Sign up for our upcoming web demo.
