A vital part of decarbonising our existing building stock will involve working to reduce the performance gap between predicted and actual in-use energy performance. Technology will play a pivotal role in the industry’s ability to achieve this, and many buildings already hold the key to getting started.
3D design, energy compliance or BIM models, created in the design and development stage, exist for the vast majority of buildings. However, these are rarely used to their full potential throughout the building’s remaining life-cycle. We have developed and trademarked the Sleeping Digital Twin initiative – the idea that these dormant models can be ‘awakened’ and turned into performance digital twins – as a means to change this.
By this theory, existing models can be updated, calibrated, and integrated with real operational data to monitor, in real time, how well a building is performing and where there is scope for improvement. It also sheds light on why a building’s energy use might diverge from initial aspirations, enabling engineers to move beyond guesswork, identify any faults, and make informed decisions on the best solutions.
A digital twin can be used to investigate a variety of ‘what if’ scenarios to get a holistic view of the options before money is spent on specific improvement or retrofit measures. Cost, energy and emissions savings, payback periods, and the impact on internal comfort conditions can all be considered, to determine the best route to improving the performance of a building. Furthermore, once the chosen solution is in place, the digital twin can be used to measure its performance against expected outcomes.
Turning existing models into digital twins can play a role in accelerating the move to net zero
Of course, better building performance should mean improved energy efficiency and reduced emissions. As such, turning existing models into digital twins can play a role in accelerating the move to net zero. Lower energy consumption also means lower costs.
While a focus on energy efficiency is crucial, this can’t come at the expense of occupant comfort. The use of a digital twin enables a balance between the two, providing a means to see the impact of different measures on occupants and understand how efficiencies can be realised in a way that’s mindful of their needs. This provides the ability to fine-tune the operation of the building in line with different occupancy scenarios and heating and ventilation requirements.
Using existing energy models in operation can also aid post-occupancy evaluations. By referring back to original design intentions, it’s possible to highlight things that may have been missed, or changed, in the building’s development that could impact how it performs on completion. A digital twin can then be used to identify how to bring a building up to predicted performance levels. In addition, this helps to prevent the same errors from being repeated in the future, ultimately resulting in improved design, build and operation.
Finally, repurposing dormant digital assets into a digital twin can support the attainment of in-use performance certifications, such as Nabers, Breeam and Leed for O+M, by providing the level of data required to illustrate that targets have been met. With these certifications ensuring that optimal performance is obtained, energy, carbon and cost savings can be realised, and the building made more attractive to tenants or buyers.
Our research found that 90% of the 167 architecture, engineering and construction practitioners surveyed see the value of energy models in operation, with the top three benefits of doing so being: to close the performance gap; achieve sustainability goals; and improve operational performance.
The appetite is there for better use of existing models, and digitisation of building performance more broadly, but barriers to making this the norm are still in place. After all, for building services engineers to benefit from the models, they need to be able to access them, and stakeholder collaboration and model handover remain areas that require improvement.
The physical and virtual should always go hand in hand, but, often, it’s easier said than done to ensure continuity across the complete building life-cycle.
The next steps are not straightforward, but facilitating a shift towards this approach has the potential to ensure building performance is optimised at every stage and that we move closer, and more quickly, towards net zero goals.
About the author
Don McLean is CEO at IES