Electric Tower, one of the operation hubs of The Hongkong Electric Co., Ltd. (HK Electric), is a showcase of the Company’s excellent efforts in undertaking retro-commissioning (RCx) projects to reduce energy consumption.
Located at Electric Tower, HK Electric’s System Control Centre is the nerve centre of the Company. It dispatches electricity generated from Lamma Power Station and monitors in real time the electricity conveyed through the Company’s transmission and distribution network to about 580,000 customers, and ensures a highly reliable electricity supply to HK Island, Apleichau and Lamma Island. Also housed inside the building is a data centre, which is another key facility of the Company where IT systems are centralised. There, the Computer Room Air Conditioning (CRAC) units are configured at high performance to maintain appropriate temperature profile round-the-clock for the smooth operation of the temperature-sensitive IT equipment. For this energy-consuming operation, the HK Electric team has successfully identified room for energy saving through retro-commissioning.
To realise the Energy Saving Opportunity (ESO) in the data centre, smart sensors are installed to collect temperature data which are transmitted to an AI-based system for analysis. The cooling output is continuously and dynamically matching with the current load of the CRAC units so that the system can optimise the speed of variable-speed fans and shut down redundant CRAC units accordingly. Energy can then be significantly saved by reducing power consumption while enhancing effectiveness of power usage.
The HK Electric team has also upgraded the aged Mechanical Ventilation Air Conditioning (MVAC) equipment of the whole Electric Tower from air-cooled to water-cooled chilled water plant in order to provide the additional cooling capacity to the above-mentioned new data centre. This ESO includes a number of enhancement projects, as well as RCx analysis to identify room for improvement through reviewing the operation of the new system and optimising efficiency. Examples include installing magnetic bearing oil-free chillers and variable-speed-drive (VSD) control for all water-side equipment, plus replacing fixed-speed primary air units (PAUs) with variable-speed ones, the speed of which is controlled by the carbon dioxide content of the office areas. In addition, belt-driven air handling units were replaced with variable-speed and electronically commutated fans having energy–efficient motors. Adjustable control parameters and performance indicators are fully utilised in the building management system to achieve energy saving through on-going commissioning. Other special features such as “Overtime Buttons (OT Buttons)” are installed at individual zones for air-conditioning supply after office hours to further optimise energy usage. The buttons are manually operated based on actual needs. A feature of free cooling through PAUs when the ambient temperature falls below 16°C is also provided.
For further energy saving without compromising the safe operation of Electric Tower, lighting appliances in car park areas, staircases and warehouses have been replaced with more energy-efficient types such as T5 LED tubes featuring photocell and occupancy sensors for smart control.
The energy consumption of Electric Tower fell by 30% in the period 2013 to 2019 primarily due to retro-commissioning and the above-mentioned enhancement projects. Leveraging its experience and expertise in energy efficiency, HK Electric is committed to adopting retro-commissioning in its operations to identify ESO and formulates improvement strategies to support environmental conservation and reduction of carbon emissions.