Trial / Demo
AtkinsRéalis have used IES Digital Twin technology to provide operational energy modelling and retro-commissioning services for more than 50 of Hong Kong’s government buildings, delivering significant energy savings to support the region’s net-zero by 2050 target.
In 2021, the Hong Kong Government announced its ambitious Climate Action Plan for 2050, pledging to reduce carbon emissions by 50% by 2030 and achieve carbon neutrality by 2050. Within this, they outlined four major decarbonisation strategies, a key area of focus being “energy saving and green buildings.”
As a major international financial and commercial centre, Hong Kong is known for its iconic skyline and impressive high-rise architecture. However, these structures pose significant sustainability challenges. Today, the region has approximately 50,000 buildings which account for 90% of its total electricity consumption, and over 60% of its carbon emissions. Addressing the energy performance of these existing buildings therefore presents significant opportunities to achieve Hong Kong’s decarbonisation goals.
As a world-leading design, engineering and project management organisation, with over 5,000 staff based in Asia Pacific alone, AtkinsRéalis have delivered many projects to help improve the energy and carbon performance of some of Hong Kong’s most iconic buildings. To support this, their Sustainable Building Design team have been using IESVE software for many years now to provide building energy modelling and green building consultancy services for new building design, including compliance with rating systems such as LEED, WELL and BEAM Plus. However, in recent years they have been exploring new ways they can expand the application of these energy models into the operational phase.
A key initiative advocated by the Hong Kong government under its Climate Action Plan is retro-commissioning (RCx) of the building stock in the community. This process involves the comprehensive evaluation of an existing building’s energy performance, encompassing the building’s systems, their components, and how they interact with one other, to identify operational improvements and energy saving opportunities (ESOs). AtkinsRéalis saw this as an opportunity to bring a fresh approach to the Hong Kong market – using energy models, developed into digital twins, to better understand the performance of these existing buildings and support the retro-commissioning process.
To date, the team has delivered retro-commissioning services for over 50 government buildings in Hong Kong, encompassing offices, disciplined and municipal services buildings, recreational facilities, and laboratories. For each of these projects, the process remains largely the same - always beginning with a whole-building energy model, created in IESVE, to represent the as-built geometry of the building, including the thermal properties of the building envelope, and building services, including HVAC and lighting systems. While many of these models are created from scratch, a number have also been “Sleeping Digital Twins” – i.e. existing models, previously created for the building during an earlier design or compliance phase, which are reutilised in operation, significantly reducing the modelling time.
These models are then calibrated with actual operational data, gathered from the building management systems, power loggers, IoT sensors and/or historic files, and visualised centrally via IES’s iSCAN data analytics platform. This generates real energy demand profiles to allow the IESVE energy model to be calibrated with actual data from the building, which is then continuously updated to create a highly accurate digital twin that mirrors the existing building in operation. All of the models created by AtkinsRealis are calibrated in line with industry best practices, such as ASHRAE Guideline 14, while the physics-based simulation capabilities offered by the IES technology suite helps to fill any missing data gaps. This makes the approach ideally suited to older buildings with limited operational data availability or inadequate sub-metering.
With the digital twin in place, the team is able to quickly identify any faulty equipment or improper operation of systems for immediate savings. They will then simulate the impact of further operational adjustments to determine the impact on building energy use and cost, as well as the building’s internal conditions, including temperature and CO2 levels. The digital twin enables clear visualisation and a detailed energy breakdown to compare the impact of different operational strategies, as well as “what-if” scenario forecasting of deeper retrofit interventions. Common measures tested include chiller plant replacements, air-side equipment upgrades, façade replacements and lighting upgrades. Meanwhile renewable installations, such as PV, can also be simulated to increase confidence in capital project investments.
Once measures have been selected and implemented within the building, the digital twin continues to serve as an invaluable measurement and verification (M&V) tool to help track the performance of any ESOs over time. The approach, which aligns to the International Performance Measurement and Verification Protocol (IPMVP) Option D, has been invaluable to the AtkinsRéalis team when proving the return on investment (ROI) for its government clients, with many projects demonstrating substantial energy savings within a reason payback of five years or less.
While results inevitably vary from building to building, the AtkinsRéalis team typically find that 5-10% operational energy savings can be readily identified through this digital twin approach, with savings as high as 15% being observed in some recreational buildings. They estimate that these projects have delivered annual electricity savings of ~7,000 MWh/year, making a significant contribution to Hong Kong’s net-zero future.
“Up until around five years ago, like many people, we were mostly using IES for compliance or green building certification purposes. However, when the Hong Kong government issued a series of tenders on retro-commissioning, we realised we could use digital twins to provide these services. While empirical calculations and simple projection estimations are typically used to derive potential energy savings, these do not consider the whole building holistically and are unable to assess indoor comfort conditions. With this innovative approach, we can actually mimic real building operations down to a very accurate time-step and see how measures will perform on different days and under different temperature conditions. This means our predictions are much more realistic for determining the impact of energy saving opportunities year-round, allowing for precise and exhaustive performance analysis of the entire building and sub-systems.”
- Peter Chan, Senior Technical Director, Sustainable Building Design, AtkinsRéalis
“Our clients especially appreciate the use of digital twins as an innovative approach to our retro-commissioning projects. This is because the model can illustrate, not only the energy consumption and energy savings that can be achieved, but also the indoor conditions of the building once various measures have been implemented. We can also run many “what if” scenario simulations before energy saving opportunities and capital investments are implemented, to better understand their impact.”
- Siu Hang Li, Associate Technical Director, Sustainable Building Design - MEP, AtkinsRéalis
