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Urban Gardens: Livability and Sustainability Can Go Hand-in-Hand

Blog0314_Singapore_TreeGroveLast month, I was able to take a few days off for a vacation in Singapore. I had an amazing time and was thrilled to be in tank tops and shorts. Singapore is a small city state at the southern tip of the Malay Peninsula. It has a population of 5.3 million in an area of 274 sq miles. That is only slightly bigger than San Francisco but with more than 6 times the population. How to make such a crowded environment livable and yet sustainable is an enormous challenge.

Singapore's greening effort dated back 50 years when it first set the vision to become a Garden City. Despite its high population density, 50% of the country is covered by plants. Now the country is entering another stage of its greening effort. It has set its vision for the 21st century to become a City in a Garden.

Gardens by the Bay is an integral part of this new vision. I was captivated by the magnificent structures and their greening features. Here is a quick view through a tourist's eyes.

Singapore's Gardens by the Bay

Gardens by the Bay is a set of urban gardens constructed on reclaimed land by the waterfront. It consists of three interconnected gardens covering 101 hectares (about 250 acres), the equivalent of 177 soccer fields. The goal behind the project is to have a "horticultural themed garden that educates, entertains, and enriches" while maintaining a small footprint. The project has won many awards including the World Building of the Year award in 2012.

The first phase of the project, the Bay South Garden, was opened in 2012. The focal points of Bay South are two mega glass conservatories used to house plants from around the world and 18 supertrees.

The Glass Conservatories Incorporate Eco-Friendly Features

Blog0314_Singapore_ConservatoryAs in any greenhouse construction, one challenge for the glass conservatories is to balance the need of light to stimulate plant growth and the need to control temperature. At the same time, the solution has to be energy efficient. The project's requirement is to limit energy usage at the conservatories to not exceed that of a standard office building.

 

Structural Elements Balance Light & Heat

To maximize sunlight, the buildings were placed in a location without obstruction. Meanwhile, structural elements, such as the combination of arches and gridshells, were selected not only to provide the needed strength to withstand weather elements but to optimize sun exposure.

Materials Minimize Heat Gain

To reduce the heat trapped in the structures, custom Double Glazed Glass was used. By customizing the metal oxide in the glass combined with low-E coating, engineers were able to optimize light and heat transmission. Temperature control is supplemented by Computerized Sunshades which are automatically deployed by heat sensors.

Energy Efficient Cooling System

As dry air takes less energy to cool, external air is first passed through a liquid desiccant, which reduces the humidity of the air from 90% to 30%. After passing through the Liquid Desiccant Cooling System, the dried air is then passed onto the chiller.

The system emphasizes recycling. Singapore generates a large amount of biomass waste from its regular tree pruning program. The pruning waste is used to generate electricity to power the chiller. The waste heat in the process is used to recycle the liquid desiccant. Wood ashes from the generator are turned into fertilizers.

Blog0314_Singapore_TreeSupertrees Offer Eco-friendly Beauty

The supertrees are giant man-made "tree-like" structures that stand at 25 to 50 meters (about 8 to 16 stories) in height. The concept was inspired by the Valley of the Giants in Australia, where visitors can  walk amongst the huge ancient trees and experience nature.

There are a total of 18 supertrees, eleven of which have embedded environmental functions. Some of them are integrated with the conservatories and are used to delicately hide discharge functions for the conservatories cooling systems. The others have photovoltaic cells built on their canopies to power up light display at night.

The tree trunks serve as vertical garden housing over 162,900 plants, comprising more than 200 species and varieties of bromeliads, orchids, ferns and tropical flowering climbers.

Blog0314_Singapore_LakeThe Lakes Complete the Ecosystem

The Gardens consist of two lakes. Filter beds and aquatic plants serve as a natural filtration system for water catchment from the Gardens. They also offer an environment for aquatic habitats such as fishes and dragonflies.

Sustainability & Livability

Urban gardens are essential to an urban community. Research showed that these gardens can improve the physical and mental wellbeing of city dwellers by offering opportunities for physical exercises, relaxation, and socialization.  

Urban gardens can come in many different forms reflecting on local culture, preferences, needs, and city plans. But regardless of its format, sustainability can be part of the design. Livability and sustainability can go hand in hand.

References:

National Geographic Channel Productions Singapore

Gardens By the Bay, Singapore: Istructe Structural Awards 2013 Submission By Atelier One

About the Gardens