23-09-2014, 03:16 PM
GREEN BUILDINGS
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Introduction
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 sitting to design, construction, operation, maintenance, renovation, and demolition. This requires close cooperation of the design team, the architects, the engineers, and the client at all project stages. The Green Building practice expands and complements the classical building design concerns of economy, utility, durability, and comfort.
Although new technologies are constantly being developed to complement current practices in creating greener structures, the common objective is that 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 available 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 needs.[4] Although some green building programs don't address the issue of the retrofitting existing homes, others do. Green construction principles can easily be applied to retrofit work as well as new construction.
Goals of green building
The concept of sustainable development can be traced to the energy (especially fossil oil) crisis and the environment pollution concern in the 1970s. The green building movement in the U.S. originated from the need and desire for more energy efficient and environmentally friendly construction practices. There are a number of motives for building green, including environmental, economic, and social benefits. However, modern sustainability initiatives call for an integrated and synergistic design to both new construction and in the retrofitting of existing structures. Also known as sustainable design, this approach integrates the building life-cycle with each green practice employed with a design-purpose to create a synergy among the practices used.
Green building brings together a vast array of practices, techniques, and skills to reduce and ultimately eliminate the impacts of buildings on the environment and human health. It often emphasizes taking advantage of renewable resources, e.g., using sunlight through passive solar, active solar, and photovoltaic techniques and using plants and trees through green roofs, rain gardens, and reduction of rainwater run-off. Many other techniques are used, such as using wood as a building material, or using packed gravel or permeable concrete instead of conventional concrete or asphalt to enhance replenishment of ground water
Need for Green buildings
According to the U.S. Environmental Protection Agency, Sick Building Syndrome
is caused by four major categories as listed below:-
Inadequate ventilation: In the early and mid-1900’s, building ventilation standards called for
approximately 15 cubic feet per minute (cfm) of outside air for each building occupant, primarily
to dilute and remove body odors. As a result of the 1973 oil embargo, however, national energy
conservation measures called for a reduction in the amount of outdoor air provided for
ventilation to 5 cfm per occupant. In many cases these reduced outdoor air ventilation rates were
found to be inadequate to maintain the health and comfort of building occupants. Inadequate
ventilation, which may also occur if heating, ventilating, and air conditioning (HVAC) systems
do not effectively distribute air to people in the building, is thought to be an important factor in
SBS. In an effort to achieve acceptable IAQ while minimizing energy consumption, the
American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) revised
its ventilation standard to provide a minimum of 15 cfm of outdoor air per person (20 cfm/person
in office spaces). Up to 60 cfm/person may be required in some spaces (such as smoking
lounges) depending on the activities that normally occur in that space (See ASHRAE Standard
62-1989).
Literature Review
GREEN BUILDINGS AND PRODUCTIVITY
Norm G. Miller, Quiana D. Gough, Susan M. Davis
Healthier space need not be new space. In fact, some new buildings are extremely
unhealthy as chemicals leach out into the air from glues, carpets, concrete and paint. There is no
reason this must be the case. The cost to provide healthier environments is modest compared to
the benefits. Healthier buildings reduce sick time and increase productivity, making it easier to
recruit and retain employees. The results provided here are based on a survey of over 500
tenants who have moved into either LEED or Energy Star labeled buildings managed by CBRE.
It is part of a much larger study that includes details on operating expenses, leasing and management available from the authors
Materials And Methods
Materials efficiency
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,dimension stone, recycled stone, recycled metal (see: copper sustainability and recyclability), and other products that are non-toxic, reusable, renewable, and/or recyclable (e.g., Trass, Linoleum, sheep wool, panels made from paper flakes, compressed earth block, adobe, baked earth, rammed earth, clay, vermiculite, flax linen, sisal, seagrass, cork, expanded clay grains, coconut, wood fibre plates, calcium sand stone, concrete (high and ultra high performance, roman self-healing concrete), etc.) The EPA (Environmental Protection Agency) also suggests using recycled industrial goods, such as coal combustion products, foundry sand, and demolition debris in construction projects 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 maximise benefits of off-site manufacture including minimising waste, maximising recycling (because manufacture is in one location), high quality elements, better OHS management, less noise and dust.
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) personnel are part of the project's planning and development process will help retain the green criteria designed at the onset of the project. 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 life-cycle, it is in the O&M phase that green practices such as recycling and air quality enhancement take place.
Data and Results
In May of 2009 a team from the University of San Diego surveyed 154 buildings
containing over 2,000 tenants that were deemed green by virtue of either the Energy Star label or
GREEN certification (at any level). Some 534 tenant responses were collected from buildings
spread across the country
While we should note that not all tenants found productivity increases and the literature suggests
that behavioral influences such as management mean as much or more than environmental
factors and we should also note that these buildings are for the most part Energy Star labeled
buildings and not necessarily GREEN buildings. If we take only those tenants who claimed an
increase in productivity we observe economic impacts based on salaries that approach the cost of
rent using a very conservative square feet per worker assumption. Total revenue enhancement
may be more or less. If we used 200 square feet per worker the results would be closer to or
exceed typical rents from this one single impact. The GREEN results were slightly better at 5.24% increased productivity but we use the entire sample here. We expect that future data on GREEN buildings, which score high on environmental dimensions, will see similar if not better results.
CONCLUSION
Analysis has lessons that can be learnt from occupants experiences and feedback in 22 Australian buildings specifically built with ESD objectives, compared with 23 conventional buildings surveyed using the Building Use Studies methodology And 154 buildings containing over 2,000 tenants that were deemed Green.
Review shows that in the green buildings studied:
• A wider spectrum of performance is evident, with the best green buildings outperforming conventional buildings, especially for thermal comfort and forgiveness. But the situation is not uniform and the green buildings studied are not better in all categories.
• Thermal comfort conditions in summer are generally poor, although there are some notable exceptions.
• Winter conditions can often be too cold.
• Ratings for design, image, health and needs are usually better.
• Perceived productivity scores are marginally lower on average, but a number of successful green buildings surpass conventional ones.
• Occupants seem to be more tolerant.
• Ratings for lighting are good.
• Internal noise is often worse.