July-August , 2022 | @ green
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By running 19 degrees Celsius water through pipes , the structure of the building becomes part of the cooling system . This cooling of the structural mass of the building can be done at night , only to be released during daytime .” a thermal storage capacity of 150 kWh . These tanks are placed on the flat concrete roof next to the chiller .
These chilled water storage tanks will typically be charged during the day when excess solar power can be used for additional chilled water production . In the morning hours before the solar panels can power the chiller , a small pump can draw chilled water for the chilled water storage tanks and provide the necessary cooling until the solar-powered chiller can start to kick in around 9.0am .
This way , the chilled water storage allows the building to operate without having to draw too much on the battery . Batteries have a limited number of charging / discharging cycles before the batteries need to be replaced . In contrast , there is no limit to a chilled water tank ’ s charging / discharging cycles .
And the environmental impact of water is minimal compared to that of batteries , another good reason for shifting part of energy storage away from batteries to thermal storage .
The building also has a small additional
thermal storage system , namely a thermally activated building system ( TABS , or floor slab cooling system ) consisting of embedded PEX pipes inside the reinforced concrete slabs .
By running 19 degrees Celsius water through pipes , the structure of the building becomes part of the cooling system . This cooling of the structural mass of the building can be done at night , only to be released during daytime .
Typically , the reinforced concrete will have a temperature swing of up to two degrees Celsius from day to night and can account for up to 40 per cent of the cooling .
This floor slab cooling system not only functions as a thermal energy storage system , but can also almost double the energy-efficiency of the chiller because the lift is greatly reduced when producing 19 degrees Celsius chilled water compared to the conventional six degree Celsius water .
For the UniKL Sustainable Energy Living Lab building , only a small area of the building uses this floor slab cooling system , namely for two of the living lab rooms only .
Stand-Alone Operation
The building has sufficient energy storage and solar panels for stand-alone operation , which means it is disconnected from the national electric grid . The stand-alone operation will be mainly for demonstration purposes , as the building typically will be grid-connected , exporting its excess energy to the surrounding UniKL buildings on campus .
Future : Grid Interactive Buildings
To avoid irreversible catastrophic climate change , the Paris Agreement stipulates that the world must slash its greenhouse gas emission to half by 2030 and fully decarbonise by the year 2050 .
This will mainly be achieved through an aggressive push for energy-efficiency and a transition to 100 per cent renewable energy . The UniKL Sustainable Energy Living Lab building does precisely that .
Moreover , with its substantive energy storage system , the building showcases the flexible demand response needed for the future electric grid powered – not by steady fossil fuel power plants – but by fluctuating renewable energy sources such as solar , wind and hydropower .
Once the electric grid becomes primarily powered by renewable energy , it becomes essential to match the demand with the supply . In other words , when the energy is available , for example , solar energy , it should be used and / or stored .
Whereas , during periods with scant energy production , for example , at night , the energy demand should be reduced and / or postponed . For this purpose , buildings can play a crucial role .
One of the dynamic loads will be parked electric vehicles , which can be told to charge / not charge / discharge when there is excess / just right / too little renewable energy available in the grid .
The charging / discharging regulation of electric cars will happen automatically . For example , we get fluctuating power rates across the day . The electric car can be programmed to charge only when the electricity rate drops below a certain rate , and at least 50 per cent charge by a particular hour , say , in the morning before going to work .
Likewise , buildings energy systems , such as cooling systems ( chilled water storage , floor slab cooling systems , fidges and freezers ), and heating systems ( hot water heating ), can be designed to be grid-interactive .
The UniKL Sustainable Energy Living Lab is an essential showcase for this new grid dynamic paradigm , where building as batteries is part of the sustainable transition . —@ Green
Gregers Reimann is from IEN Consultants Sdn Bhd - a pioneering green building consultancy in Malaysia specialising in energy-efficient and healthy buildings .