Creating with nature: Green building basics
From the print edition
For local architect Rodrigo Carazo, green building means simply “adapting to our natural surroundings without damaging or destroying it,” through a “constant process of learning, adapting and experimenting.”
To Alberto Negrini, an architect and professor of environmental design, green building is a process of “relearning to live with nature.” He believes that true environmental design must spring from the surrounding nature and culture. The final objective of environmental design, he said at a recent symposium at the National University, “is achieving happiness arising from people living in harmony with their environment.”
Roberto Meza, an engineer specializing in certifying green buildings, aims even higher, positing that green building and design should not only avoid harming the environment, but also should actively work to restore and improve it: “We have to move from causing less harm to doing more good.”
Where all agree is that there is no established path to building sustainably; creativity, innovation and cooperation among those involved in a project, rather than following established formulas, are most important for achieving good results. Designers also agree that while green building seeks ambitious ends, it’s simpler than it sounds, often involving applying common sense or rediscovering traditional approaches to living with the environment.
In addition, because each building is in a different setting and responds to the needs of different inhabitants, none should be exactly alike. All green designers and builders also stress that green building, if done right, can be less expensive in both the short and long term.
At minimum, experts say, green buildings should strive to minimize the use of energy in both the construction and operation of buildings, use other resources such as water rationally, avoid the use of toxic materials and otherwise cause reduced impacts on the environment. Improving existing buildings to make them more environmentally friendly is also an important element of green building.
Form and function
While the use of environmentally friendly building materials and devices to save water and energy are part of green building, most experts say that more important are basic design elements that don’t require added investment or gadgetry. In a tropical climate, eliminating or reducing the need for air conditioning (often more than 60 percent of a building’s energy costs) is one of the most important goals, most easily achieved by ensuring cross-ventilation and minimizing exposure to sunlight.
In Costa Rica’s Central Valley, for example, this could entail creating a long and narrow building along an east-west axis, so that prevailing north-easterly winds ventilate all of the rooms, while the building, because of its orientation, would receive little direct morning or afternoon sun. Wide eaves, porches, awnings and the planting of shade trees serve the same function of preventing sunlight from heating the interior of a building. High ceilings, with ventilation in the roof and near the tops of the walls, can also make for cooler interiors.
In a very hot and wet climate, houses can be built on stilts to increase air circulation and reduce exposure to moisture. Conversely, a house in a hot, dry climate can be built close to the ground with thick walls, in order to use and conserve the coolness of the earth.
Green architects and builders are quick to point out that these features are elements of traditional construction in Costa Rica and around the world, showing that green design is nothing new, although much of it has been forgotten for a time.
Green building materials
While perhaps less crucial than basic design, the choice of building materials is very important in determining the ecological and aesthetic impact of a building. Following are some of the more popular options for green building in Costa Rica:
• Wood. In Costa Rica, the use of wood in construction is undergoing a rebirth. Once among the most common building materials, the use of wood dropped off steeply over the past decades as reinforced concrete became the norm, while supplies of native wood dried up because of indiscriminate harvesting, waste and destruction of forests.
More recently, builders, architects and – more importantly – their clients, have rediscovered the beauty, usefulness and practicality of wood. Meanwhile, thinking among many environmentalists regarding the widespread use of wood as a building material has taken a sharp turn; once seen as a threat to forests and biodiversity, it is now more likely to be perceived as a potent element in the fight against climate change because of wood’s ability to trap carbon dioxide from the atmosphere in long-lasting buildings, furniture and other goods.
However, assuring the supply of wood for construction without threatening natural forests and wildlife is still a challenge. While reforestation is helping meet growing demand, Costa Rica must import wood to meet demand, mostly from South America. Where the provenance of wood is unknown, the use of certified wood is recommended by green building experts to ensure that it has been grown and harvested with due regard for the environment.
• Bamboo. Most of what holds true for wood is doubly true for bamboo. Once widely used by traditional cultures in the Americas and elsewhere, the impressive qualities and beauty of bamboo as a building material are being rediscovered and widely applied by green architects and builders (TT, Sept. 30, 2011). Moreover, because bamboo, which is a grass, not a tree, grows very quickly, it is even more effective as a buffer against climate change than wood, while production can be more easily increased to meet demand. Like wood, bamboo must be properly selected, treated and utilized to avoid rot or damage by insects.
• Concrete. Because the process of making concrete is energy-intensive, releases large amounts of carbon dioxide into the atmosphere and also requires large-scale mining of rocks and minerals, the massive use of this material in construction – now the norm – is highly damaging to the environment. However, because of its low cost, strength and versatility, very few architects or builders would be willing to renounce its use altogether. In fact, most green buildings use concrete to a greater or lesser degree. Minimizing its use, however, is a goal most green designers share.
The cement industry worldwide has responded to criticism by making a significant effort to reduce carbon emissions and improve mining practices. (Holcim, a leading cement manufacturer, houses its local offices in an impressive green building in Alajuela.)
However, despite significant progress, even including the marketing of “green” cement, the process of making concrete, as even its advocates admit, is inherently polluting. That the industry has invested so much effort and money in improving its image and processes, however, is a good indication that the green building movement is here to stay.
• Earth. In hot climates, one strategy for green, low-energy building is to create more massive structures that will retain nighttime coolness throughout the day. Traditionally, adobe and stone structures in Latin America filled this role. While concrete block has largely taken the place of these materials, it does not retain coolness to the same degree, and is environmentally unfriendly in comparison. As an alternative, green designers and engineers have created building systems using blocks made of compacted earth, bags filled with soil, and variations on traditional adobe or earthen structures.
• Foam. A similar strategy of building to retain coolness, but in lightweight form, is represented by systems using styrofoam, usually based on a metal frame or mesh and coated with sprayed-on cement. These systems are extremely efficient in maintaining temperatures.
According to Diego Estrada, general manager of Panelco, a Costa Rican manufacturer of such systems, living in a home built with foam is like “living in an ice chest.” They are also versatile and inexpensive compared to many other building methods. However, one common criticism is that styrofoam, once manufactured, is difficult to dispose of, and will last for hundreds of years beyond the probable life span of the building.
• Metal. While the manufacture of steel and aluminum is energy-and resource-intensive and polluting, the judicious use of these materials to build lightweight structures – ideal for a mild climate like Costa Rica’s – saves a great deal of energy and resources compared with traditional concrete construction. These buildings often incorporate broad expanses of glass, along with panels of wood, fiber-cement or other materials.
• Reutilized and recycled materials. A basic tenet of sustainable building is to reuse or recycle materials whenever possible. Thus, wood, brick, stone, windows and doors from older structures are salvaged and reused, and new products made from recycled materials, such as steel and aluminum, also are used. Another basic precept is to use local materials wherever possible, to avoid the added cost and pollution incurred by shipping.
Water and Energy
Saving water, while less critical in rainy Costa Rica than other parts of the world, is still important, and will become more so if Costa Rica, as predicted, becomes hotter and drier as a result of climate change (TT, Aug. 12, 2011). Elements of green building that could contribute to saving water include systems to collect and use rainwater for household use and irrigation, reusing of water from sinks, baths and washing machines for irrigation (to this end, using biodegradable soaps and detergents is very important), as well as conservation measures such as reduced-flow nozzles in sinks and showers and double-flush toilets. Landscaping with native plants accustomed to the cycle of dry and rainy seasons requires less or no irrigation.
Many options for saving – and producing – energy for homes and other buildings exist, and will be the topic of next month’s Sustainable Living section.
Green Building Resources
Mario Carazo: www.carazoarquitectos.com
Bruno Stagno: www.brunostagno.info
Pietro Stagno and Luz Letelier: www.luzdepiedra.com
Adrián Bonilla: [email protected]
Eco Materiales: www.ecomaterialescr.com
Green Center: www.greencentercr.com
Green Pages Directory: www.paginasverdescr.com
Pura Verde Directory: www.pura-verde.com
Green Building Certification
Roberto Meza, Sphera Consultants: www.sphera-sbc.com
Costa Rica Green Building Council: www.costaricagbc.org
Herberth Méndez, FUDEU: [email protected]
Alexandra Rodríguez, INTECO: [email protected]
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