Gardens By The Bay - Environmental Sustainability

Gardens By The Bay
Marina South, Singapore
June 2013

After spending the day at Gardens By The Bay's "Flight Of Fancy", Merlion Wayfarer was wondering about the environmental impact of artificially cooling two huge conservatories and generating enough power to keep a seven-storey high waterfall running non-stop for 12 hours daily.

Curious, she did some research...

Comprising two glass biomes, the cooled conservatories - Flower Dome and Cloud Forest - replicate the cool-dry climate of the Mediterranean and the semi-arid sub-tropical regions and cool-moist climate of the Tropical Montane region . A diverse collection of plants not commonly seen in equatorial weather are housed here.

A series of cutting-edge technologies for energy-efficient solutions in cooling are built within the conservatories:
  • Use of biofuel
The energy used for powering the chillers is produced by a biomass furnace that uses horticultural waste produced within Gardens by the Bay and island-wide by National Parks Board.
  • Minimizing solar heat gain
The two conservatories are fitted with specially selected glass that allows optimal light in for plants, but reduces a substantial amount of heat. The roof is fitted with a sensor-operated retractable sails that opens automatically to provide shade to the plants when it gets too hot.
  • Cooling only the occupied zones
The Conservatories apply the strategy of cooling only the lower levels, thus reducing the volume of air to be cooled. This is achieved through thermal stratification - ground cooling by chilled water pipes cast within the floor slabs enabling cool air to settle at the lower occupied zone while the warm air rises and is vented out at high levels.
  • De-humidifying the air before cooling
To reduce the amount of energy required in the cooling process, the air in the conservatories is de-humidified by liquid desiccant (a drying agent) before it is cooled. This desiccant is recycled using the waste heat from the burning of the biomass and accumulated at the higher levels of the cooled conservatories.
  • Generating energy and harnessing waste heat
Electricity is generated on-site to run the chillers that cool the Conservatories. At the same time, waste heat is captured in the process to regenerate the liquid desiccant. This co-generation of energy is achieved by the use of a Combined Heat Power (CHP) steam turbine that is fed by horticultural waste from the Gardens and other parks around Singapore. This reduces dependency on the electrical grid.

(Source : Gardens By The Bay)

An energy modelling study showed that by applying the technologies, the energy consumption for the conservatories is comparable to that of an average commercial building in Singapore of the same footprint and height, normalized over a 24-hour cooling period.

This helps achieve at least 30% savings in energy consumption, compared to conventional cooling technologies.

(This article is part of Merlion Wayfarer Goes Green's Gardens By The Bay series.)

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