Effectiveness of Tensile Membrane Structures in Green Building

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    1 Espiritu

    Effectiveness

    of TensileMembrane

    Structures in

    GreenBuilding

    Espiritu,Arianne Rose F.

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    Effectiveness of Tensile Membrane Structures in Green Building

    I. IntroductionA. Background of the Study

    The advocacy of Green Building has been around for many years now. Individuals

    and organizations from different professions are one in the goal of discovering, reinventing

    and re-using green building materials and methods that are in line with this advocacy.

    Normally, what comes to mind when one strikes up a discussion regarding Green Building is

    the harnessing of the natural forces in order to provide for man's basic power needs. This is

    true but it does not fully encompass the essence of the Green Building advocacy. Green

    Building is also the use of context and climate in building a place for man that optimizes the

    use of the natural forces to create a holistic place of work, play and rest, among others. Green

    Building includes not only harnessing the natural forces to create electric power, but also

    implementing green building methods that have been used many centuries and have thrived

    in the rural areas of most countries since they have been replaced by fleeting new building

    styles that do not, in any manner, so to speak, take into consideration context and climate.

    Green building also includes the use of green building materials to be incorporated in the

    design in order to produce the minimum amount of carbon footprint during and after the

    building is constructed. These factors are to be taken into account if one is to follow green

    building into ones design.

    HARNESSING NATURES FORCES

    SOLAR ENERGY

    The sun gives the earth a total of 174 petawatts of energy. 30% of this amount is

    absorbed by the clouds, oceans and land masses which is 3,850,000 EJ. This is more than

    enough to provide for one hour of energy consumption in one years span. If harnessed

    properly, either through passive or active technologies, the suns energy would have

    efficiently provided for most of the power needs of man.

    There are two kinds of solar technology: passive solar and active solar technologies. Passive

    solar technologies include methods of building like orienting the building towards the sun

    and incorporating thermal materials into thebuildings faade. Active solar technologies on

    the other hand, include the use of photovoltaic cells and solar thermal collectors.

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    Since the ancient civilizations of the Greeks and Chinese, building orientations were

    referenced from the latitude of a place to the Sun in order to receive the optimum needed

    daylight to warmth and light the interiors. They oriented their buildings due South in order to

    achieve this. However, the captured heat was also released through open windows. The

    Romans came to a solution of using glass windows to trap the required amount of heat inside.

    This was around 50A.D. These glass windows were essential for the greenhouse effect to take

    place. The use of glass was so efficient that the wealthy classes in the Roman society had a

    room called the heeliocaminus added to their villas. However proliferate the use of glass was

    during the glory days of Rome, it also saw its decline with the fall of the Roman empire

    together with the use of solar energy. In the seventeenth century, however, better glass-

    making techniques were invented which thus led to the incorporation of solar energy in the

    buildings design once more.

    In the 1500s , photovoltaic power was discovered in the height of the Industrial Revolution,

    by Heinrich Becquerel when he witnessed solar power transformed into electric power. With

    this discovery, solar panels were built starting in the 1700s, to harness the suns energy and

    utilize it to help in supplying the electrical power needs of a community.

    RAINWATER HARVESTING

    Another prominent way of harnessing natures forces to produce energy needed by

    man is through rainwater collection or Rainwater Harvesting as it is more popularly known.

    The idea of rainwater harvesting was first conceived in 3 BC when farming communities of

    Baluchistan and Kutch used rain for irrigation. It was also used by the Chola Kings of the

    Ancient Tamil Nadu, India and the Indus Valley Civilizations.

    The practice of rainwater harvesting still proliferates to this day. Rainwater is used to provide

    for the domestic chores where water is needed such as watering plants, water for livestock

    and water for small irrigations. The use of this method has apparently been very effective in

    lowering the amount of water level dependencies around the world that new building laws in

    some places, like Bermuda and the US Virgin islands, require new construction projects to

    include rooftop rainwater collection systems to provide for the water needs of residents.

    Below is a diagram of the typical installation of a rainwater collection system.

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    As seen in the diagram, rainwater is flowed through pipes that lead to an outdoor storage

    tank. The level of purification the collected water undergoes depends on the type of use for

    which it is collected. Generally, water collected is used for watering plants and thereforerequires no purification at all. But on occasions when this water is collected and used for

    drinking purposes, then a high level of purification is needed.

    Other than Rainwater Harvesting, other methods for the collective reuse of water are also

    available. Some of these methods are the reed bed system and the Playpump system.

    The reed bed system is a method of water purification which utilizes either natural or man-

    made floodplains. Artificial reed bed systems are useful in removing pollutants from grey

    water. The process of purification that takes place in the system is very much similar to the

    conventional sewage treatment process without the artificial aeration, of course because the

    same organisms are used.

    The PlayPump system on the otherhand, is an innovative method of collecting and

    distributing water for communities which used to have unclean and unpurified water, or in

    worse cases, have no water at all. This system was first introduced in the rural areas of South

    Africa where most residents of the communities there have to travel a long way just to collect

    clean and safe water and travel back to return to their families.

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    The above photo shows a typical section of the Playpump. The concept behind this system is

    to incorporate work with play. Children are expected to use the knob (1) as a merry-go-round

    of sorts so that it could generate enough hydraulic power and momentum to pump water from

    the waterbed (2) until it reaches the storage tank(4). When the tank is full, people can now

    utilize the water stored. This Playpump system is usually situated in schools where a crowd

    of children could play without realizing that they are helping in collecting water for their

    community. However, this Playpump system was not designed to be the sole provider of the

    water needs of a community as opposed to what most have expected from it.

    GREEN BUILDING METHODS OF CONSTRUCTION

    PASSIVE COOLING

    According to Norbert Lechners book entitled Heating, Cooling, Lighting, there exists

    a three-tier design approach for passive cooling of a building. The first tier consists of heat

    Avoidance methods, tier 2: Passive Cooling, tier3: Mechanical Cooling.

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    At this level, the designer does everything possible to minimize heat gain in the building.

    Strategies at this level include appropriate use of shading, orientation, color, vegetation,

    insulation, daylight and control of internal heat sources. (Lechner, 258) But sure enough

    heat avoidance is not in itself sufficient to keep temperatures low enough. This is where

    passive cooling systems come in. Using these systems, the amount of heat in a structure is not

    only minimized but also, temperatures are lowered. When both passive cooling and heat

    avoidance strategies are insufficient in maintaining thermal comfort, Mechanical Cooling will

    be employed. But as much as possible, the first two tiers should be enough in keeping the

    thermal comfort level.

    Most of these heat avoidance strategies and methods have been around since the ancient

    times and are now thriving in the indigenous communities. Decades of experience in trying to

    construct buildings that would embody the culture of a place and society without of course

    neglecting the primary purpose of giving shelter to man, has brought us these indigenous and

    historical use of passive cooling. In Asia, for example, especially in countries in the

    Southeast, houses are on stilts that not only protect people from high tide (since houses were

    usually situated along bodies of water), but also allow wind to pass under the dwelling spaces

    w