Singapore's national garden goes energy-efficient

The Flower Dome, spanning 1.2 hectares and 45 metres in height, replicates the cool-dry climate of the Mediterranean and semi-arid subtropical regions such as South Africa, Madagascar, Western Australia and the Mediterranean Basin.

The Dome is fitted with 3,332 glass panels of varying shapes and sizes. Spectrally-selective glass and light sensor-operated shadings help to minimize solar heat gain while allowing maximum light for plants.

Spectrally selective glass coatings filter out 40 percent to 70 percent of the heat normally transmitted through insulated window glass or glazing, so lesser heat will pass through.

To ensure cool air settles at the lower occupied zone, and warm air is allowed to rise and released at high levels, the process of thermal stratification is applied. Ground-cooling, which is achieved by chilled water pipes cast within the ground slabs are also added to enhance the process.

The Cloud Forest Conservatory, stretching 0.8 hectares, greets visitors with a 35-metre mountain and a 30-metre waterfall. The area replicates the Tropical Montane climate such as Mount Kinabalu in Sabah, Malaysia, and the higher regions of South America.

There are nine zones of biodiversity and ecology from different parts of the world within the conservatory itself. Some include the "Lost World" which features plants found at 2,000 meters above sea levels, and "Crystal Mountain" which resembles caves within a mountain.

At the top of the man-made mountain, hydraulic sprays are fitted around to keep the temperature between 23 to 25 degrees, to imitate the climatic state of 2,000 metres above sea levels.

A liquid desiccant system is used to achieve greater energy savings in the cooling process. It first de-humidifies the air with a liquid desiccant, then cools the dry air. This reduces the need to over-cool the air to remove its moisture as in a conventional air-conditioning system.

The 18 Supertrees in the Gardens were modelled and constructed after the form and function of mature trees. They create height to balance the current and future tall developments in the Marina Bay Sands area.

Some of them are embedded with photovoltaic cells to generate solar energy so they can light up at night. Others will be integrated with the Cooled Conservatories and serve as air exhaust receptacles.

The Supertree has four major parts: the reinforcement concrete core with an inner vertical structure that upholds the Supertree; the trunk which has a steel frame attached around the reinforcement concrete core; planting panels which are installed on the trunk in preparation for the planting of the living skin; and the canopy.

Shaped like an inverted umbrella, the canopy is assembled and hoisted through a hydraulic jack system, with the exception of the 50 metres Supertree canopy which will be assembled at its final height.

Dragonfly Lake, at the west side of Bay South Garden is about 960 meters in length, with 72,000 cubic metres of water. It is a natural filtration system for water from the Gardens' catchment and provides aquatic habitats for biodiversity. Water run-off from within the Gardens is captured by the lake system, cleaned by aquatic plants before being discharged into the reservoir. Naturally treated water from the lake system is also used in the built-in irrigation system for the Gardens.