The Vlaams Instituut voor Biotechnologie VIB) renewed the cooling system of a research building in Zwijnaarde. In order to make the optimal choice for this extensive investment, the VIB asked Ingenium to work out various scenarios. We took a broad look at what was possible on the site, and how energy could be exchanged with other facilities in the future. Besides the concept, we were also responsible for the concrete design and the follow-up of the implementation.
The building with labs and offices on the Technologiepark in Zwijnaarde was commissioned in 2002. After 2 decades, the day and night running cooling installation needed to be replaced. It consisted of 2 ice water machines combined with 2 open cooling towers and the possibility of freecooling. The thermal capacity was 1.9 MW.
In all our scenarios we assumed changing outdoor conditions in the future. Because of climate change, we can expect higher temperatures in the summers than foreseen when the building was constructed in 2002. Moreover, there are more users in the building now than there were then. Based on a simulation, we decided to increase the total cooling capacity to 2.4 MW. To keep the system sufficiently redundant in the future, we installed 3 machines instead of 2. Because of this permanent availability, we provided a rental chiller during the works so that the activities in the building could continue continuously.
The labs in the building use 7-degree Celsius ice water that is distributed through a closed circuit. After use, the heated water must be cooled down again. For this, we examined several scenarios: air-water chillers, water-water chillers with dry coolers or metadiabatic coolers and water-water chillers with cooling towers. We also looked at 2 options in detail: freecooling (without active cooling) and heat recovery (instead of blowing off the heat).
In addition to the total investment and operating costs andCO2 emissions, we also took practical integration into account for each scenario: Noise production and space occupation were the main practical challenges and helped to decide on the final scenario: 3 chillers with open cooling towers.
Because we always like to work as sustainably and energy-efficiently as possible in our concept, we also envisioned scenarios where excess heat from the labs would be recovered from the refrigeration units to heat the lab building. This would reduce gas consumption by 60 percent. This option was not held back by the VIB at the time, but the new installations are designed to lift that option in the future anyway.
In the original installation, the ice water was permanently pumped around at full flow, regardless of the season and (thus) variations in demand. This was not the most energy-efficient option. So we converted that existing ice water circuit to a variable-flow system. This not only saves electricity, but is also better for the efficiency of the cooling systems.
Cooling towers normally operate on city water. Since heat is evacuated through evaporation, some of the water is always lost. To reduce city water consumption, we connected rainwater buffers to the cooling towers. In a break tank, city water is mixed with rainwater. From there, the water level in the cooling towers is kept permanently at the right level.
VIB 's investment should pay off over 2-3 decades. By examining and weighing various future scenarios with the broadest possible perspective, looking at both quick wins and possible long-term synergies, the total cost of ownership (TCO) becomes quite a bit more favorable.
Want to know more about making (cooling) installations in large buildings more sustainable?
Then contact our expert Nico Vandewiele: nico.vandewiele@ingenium.be - 050 40 45 30.
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