Green building refers to a structure and using process that is environmentally responsible and resource-efficient throughout a building’s life-cycle. The Green Building project differs from conventional building projects by assigning equal priorities to economical, social, and environmental goals. LCA recognized that it is critical to the design of environmentally responsible buildings. Research shows that such a building improves tenants’ satisfaction and health, enabling higher employee productivity. As a result of the increased interest in green building concepts and practices, a number of organizations have developed standards, codes and rating systems conservation of water, energy, and building materials, and occupant comfort and health.
Keywords: sustainability, life cycle assessment, photovoltaic technique,
Green building (also known as green construction or sustainable building) refers to a structure and using process that is environmentally responsible and resource-efficient throughout a building’s life-cycle: from site selection to design, construction, operation, maintenance, renovation, and demolition. This practice expands and complements the classical building design concerns of economy, utility, durability, and comfort
- Green building brings together a vast array of practices and techniques to reduce and ultimately eliminate the impacts of buildings on the environment and human health
- Green buildings are designed to reduce the overall impact of the built environment on human health and the natural environment by:
- Efficiently using energy, water, and other resources
- Protecting occupant health and improving employee productivity
- Reducing waste, pollution and environmental degradation
A similar concept is natural building, which is usually on a smaller scale and tends to focus on the use of natural materials that are locally. Other related topics include sustainable design and green architecture.
Sustainability may be defined as meeting the needs of present generations without compromising the ability of future generations to meet their need.A 2009 report by the U.S. General Services Administration found 12 sustainably designed buildings cost less to operate and have excellent energy performance. In addition, occupants were more satisfied with the overall building than those in typical commercial buildings.
Reducing environmental impact:
Green building practices aim to reduce the environmental impact of buildings, and the very first rule is, do not build in sprawl. No matter how much grass you put on your roof, no matter how many energy-efficient windows, etc., you use, if you build in sprawl, you’ve just defeated your purpose. Buildings account for a large amount of land .According to the National Resource Inventory, approximately 107 million acres (430,000 km2) of land in the United States are developed. The International Energy Agency released a publication that estimated that existing buildings are responsible for more that 40% of the world’s total primary energy consumption and for 24% of global carbon dioxide emissions.
It often emphasizes taking advantage of renewable resources, e.g., using sunlight through passive solar and active solar and photovoltaic techniques and using plants and trees through green roofs, rain gardens, and for reduction of rainwater run-off. Many other techniques, such as using packed gravel or permeable concrete instead of conventional concrete or asphalt to enhance replenishment of ground water, are used as well.
While the practices, or technologies, employed in green building they may differ from region to region, there are fundamental principles that persist from which the method is derived: Site selection and Structure Design Efficiency, Energy Efficiency, water efficiency , Materials efficiency, Indoor Environmental Quality Enhancement, Operations and Maintenance Optimization, and Waste and Toxics Reduction. The essence of green building is an optimization of one or more of these principles.
Life cycle assessment (LCA)
A life cycle assessment assesses a full range of impacts on environment associated with all the stages of a process from cradle-to-grave taken into account include embodied energy, global warming potential, resource use, air pollution, water pollution, and waste.LCA recognized that it is critical to the design of environmentally responsible buildings.
Athena software tools are especially useful early in the design process. They allow designers to experiment with different material mixes to achieve the most effective combination.
A more product-oriented tool is the BEES (Building for Environmental and Economic Sustainability) software, which combines environmental measures with economic indicators to provide a final rating. Particularly useful at the specification and procurement stage of a project, BEES 4.0 includes data on 230 products such as siding and sheathing.
Site selection and structure design efficiency
The foundation of any construction project is rooted in the concept and design stages. The concept stage, in fact, is one of the major steps in a project life cycle, as it has the largest impact on cost and performance. In designing environmentally optimal buildings, the objective is to minimize the total environmental impact associated with all life-cycle stages of the building project. However, building as a process is not as streamlined as an industrial process, and are much more complex products, composed of a multitude of materials and components each constituting various design variables to be decided at the design stage. A variation of every design variable may affect the environment during all the building’s relevant life-cycle stages.
Green buildings often include measures to reduce energy consumption – both the embodied energy required to extract, process, transport and install building materials and operating energy to provide services such as heating and power for equipment.
To reduce operating energy use, high-efficiency windows and insulation in walls, ceilings, and floors increase the efficiency of the building envelope . Another strategy, passive solar building design, is often implemented in low-energy homes. Designers orient windows and walls and place awnings, porches, and trees to shade windows and roofs during the summer while maximizing solar gain in the winter. In addition, effective window placement can provide more natural light and lessen the need for electric lighting during the day. Solar water heating further reduces energy costs.
Onsite generation of renewable energy through solar power , wind power, hydro power, or biomass can significantly reduce the environmental impact of the building. Power generation is generally the most expensive feature to add to a building.
Reducing water consumption and protecting water quality are key objectives in sustainable building. One critical issue of water consumption is that in many areas, the demands on the supplying aquifer exceed its ability to replenish itself. To the maximum extent feasible, facilities should increase their dependence on water that is collected, used, purified, and reused on-site. The protection and conservation of water throughout the life of a building may be accomplished by designing for dual plumbing that recycles water in toilet flushing. Waste-water may be minimized by utilizing water conserving fixtures such as ultra-low flush toilets and low-flow shower heads. Bidets help eliminate the use of toilet paper, reducing sewer traffic and increasing possibilities of re-using water on-site. Point of use water treatment and heating improves both water quality and energy efficiency while reducing the amount of water in circulation. The use of non-sewage and grey water for on-site use such as site-irrigation will minimize demands on the local aquifer.
Building materials typically considered to be ‘green’ include lumber from forests that have been certified to a third-party forest standard, rapidly renewable plant materials like bamboo and straw and other products that are non-toxic, reusable, renewable, and recyclable (e.g., , Linoleum, sheep wool, panels made from paper flakes, etc.) The EPA (Environmental Protection Agency) also suggests using recycled industrial goods, Building materials should be extracted and manufactured locally to the building site to minimize the energy embedded in their transportation. Where possible, building elements should be manufactured off-site and delivered to site, to increase benefits of off-site manufacture including reduce waste, increase recycling high quality elements, better OHS management, less noise and dust.
Indoor environmental quality enhancement
The Indoor Environmental Quality (IEQ) category in LEED standards, one of the five environmental categories, was created to provide comfort, well-being, and productivity of occupants. The LEED IEQ category addresses design and construction guidelines especially: indoor air quality (IAQ), thermal quality, and lighting quality.
Indoor Air Quality seeks to reduce volatile organic compounds, Buildings rely on a properly designed ventilation system provide adequate ventilation of cleaner air from outdoors or re-circulated, filtered air as well as isolated operations from other occupancies. During the design and construction process choosing construction materials and interior finish products with zero or low VOC emissions will improve IAQ. Most building materials and cleaning/maintenance products emit gases, some of them toxic, such as many VOCs including formaldehyde. These gases can have a detrimental impact on occupants’ health, comfort, and productivity. Avoiding these products will increase a building’s IEQ. LEED, HQ and Green Star contain specifications on use of low-emitting interior. Draft LEED 2012 is about to expand the scope of the involved products. BREEAM limits formaldehyde emissions, no other VOCs.
Also important to indoor air quality is the control of moisture accumulation leading to mold growth and the presence of bacteria and viruses as well as dust mites and other organisms and microbiological concerns. Water intrusion through a building’s envelope. A well-insulated and tightly-sealed envelope will reduce moisture problems but adequate ventilation is also necessary to eliminate moisture from sources indoors including human metabolic processes, cooking, bathing, cleaning, and other activities.
Personal temperature and airflow control over the HVAC system coupled with a properly designed building envelope will also aid in increasing a building’s thermal quality. Solid wood products, particularly flooring, are often specified in environments where occupants are known to have allergies to dust or other particulates. Wood itself is considered to be hypo-allergenic and its smooth surfaces prevent the buildup of particles common in soft finishes like carpetInteractions among all the indoor components and the occupants together form the processes that determine the indoor air quality
Operations and maintenance optimization
No matter how sustainable a building may have been in its design and construction, it can only remain so if it is operated responsibly and maintained properly. Ensuring operations and maintenance (O&M) Every aspect of green building is integrated into the O&M phase of a building’s life. The addition of new green technologies also falls on the O&M staff. Although the goal of waste reduction may be applied during the design, construction and demolition phases of a building’s lifecycle, it is in the O&M phase that green practices such as recycling and air quality enhancement take place.
Green architecture also seeks to reduce waste of energy, water and materials used during construction. For example, in California nearly 60% of the state’s waste comes from commercial building. During the construction phase, one goal should be to reduce the amount of material going to landfills. Well-designed buildings also help reduce the amount of waste generated by the occupants as well, by providing on-site solutions such as compost bins to reduce matter going to landfills.
When buildings reach the end of their useful life, they are typically demolished and hauled to landfills. Deconstruction is a method of harvesting what is commonly considered “waste” and reclaiming it into useful building material. Extending the useful life of a structure also reduces waste – building materials such as wood that are light and easy to work with make renovations easier.
To reduce the impact on wells or water treatment plants, several options exist. “Grey water”, wastewater from sources such as dishwashing or washing machines, can be used for subsurface irrigation, or if treated, for non-potable purposes, e.g., to flush toilets and wash cars. Rainwater collectors are used for similar purposes.
As a result of the increased interest in green building concepts and practices, a number of organizations have developed standards, codes and rating systems building professionals and consumers embrace green building with confidence.In some cases, codes are written so local governments can adopt them as bylaws to reduce the local environmental impact of buildings.
Green building rating systems such as BREEAM (United Kingdom), LEED (United States and Canada), and CASBEE (Japan) help consumers to determine a structure’s level of environmental performance. They award credits for optional building features that support green design in categories such as location and maintenance of building site.Conservation of water, energy, and building materials, and occupant comfort and health. The number of credits generally determines the level of achievement