JEC Project:
Energy Saving Thermal Storage System for The Hong Kong Institute of Education

DeveloperThe Hong Kong Institute of Education
JEC ScopeThermal Storage System Installation
LocationHong Kong
Project Completion Date2009

JEC installed a Thermal Storage System with a storage capacity of 1400 Ton-Hour for The Hong Kong Institute of Education. The system is connected to the existing chilled water supply system and has a storage capacity of 1400 Ton-Hour. The Thermal Storage System is an energy saving method of air-conditioning which applies Phase Change Material (PCM) technology.

Phase Change Material Technology
In this project, PCM with an 8 oC (+/-0.5 oC) phase change temperature was used and permanently sealed inside chemical inert plastic containers. The material has a high heat of fusion which is capable of storing and releasing large amounts of energy.
During off peak periods, water from the existing chiller plant is supplied to the thermal storage system. The water is supplied at 6oC which provides a 2oC temperature difference across the thermal tank. This lower temperature causes the PCM to solidify. The solid PCM is then stored at 6oC and later used to chill water during peak periods. The chilled water thus charges the Phase Change Material during off-peak periods when energy is cheaper with an estimated energy saving of 8%.

Building Management Control of the Thermal Storage System
The existing chiller plant’s demand charge is monitored in real time, with the data continuously transmitted to the existing Building Management System (BMS). If chiller demand exceeds a limiting value then a control signal is transmitted to the BMS and the Thermal Storage System. This signal controls the chiller plant load and triggers the Thermal Storage to release its stored cooled water. Cooled water stored at night can thus supplement the air conditioning system at peak times, which reduces the system’s required capacity and saves energy.

Image A member of the Jardine Matheson Group