Construction industry is one of the largest consumers of raw material and energy during its lifecycle and therefore has a profound impact on environment. Buildings not only protect us from extremes of nature, but they also affect the natural environment, human health and the economy. For example, to heat/cool and power our buildings, large amount of energy is consumed. This energy is obtained primarily by burning fossil fuels - oil, natural gas and coal – which generate significant amounts of carbon dioxide (CO2), the most widespread greenhouse gas (GHG). With modernization, environmental impact of buildings is becoming more apparent. Buildings may be associated with the release of GHG in other ways, for example, construction and demolition debris that degrades in landfills may generate methane, and the extraction and manufacturing of building materials may also generate GHG emissions.
According to World Green Building Council (WGBC) "buildings use 32% of the world's resources in construction. They are responsible for around 40% of global energy use and generate up to 30% of global GHG emissions." Therefore, to slowdown the pace of global climate change, efforts are to be put in reducing the energy use and GHG emissions produced by buildings during its lifecycle. If we do life cycle analysis of the building then same could be summ- arized as shown in the Table 1.
For these adverse impacts of a building, "Green Building Construction" concept is gaining importance. Green Building Construction is the practice of creating structures using processes that are environmentally responsible and resource-efficient during design, construction, operation, maintenance, renovation and deconstruction of a building, i.e. throughout its lifecycle. This practice expands and complements the classical building design concerns of economy, utility, durability and comfort. Green Buildings are designed to reduce the overall adverse impact of the built environment on human health and natural environment by:
- Efficiently using/conserving/restoring energy, water and other resources
- Protecting occupant health and improving productivity
- Reducing waste, pollution, heat island effect and environmental degradation
- Optimize life cycle economic performance
- Enhance and protect biodiversity and ecosystems
Some Terms Related To Green BuildingSustainability in its environmental usages refers to the potential longevity of vital human ecological support systems and balance with the impacts of unsustainable design. As per the World Commission on Environment and Development, 1987 (U.N. Brundtland Report), it is "meeting the needs of present generations without compromising the ability of future generations to meet their needs." Green Buildings are for sustainability and will incorporate sustainable materials (reused, recycled, or made from renewable resources) in the construction; create healthy indoor environment with minimal pollutants (reduced harmful emissions); and/or feature landscaping that reduces water usage (e.g. by using native plants that survive without extra watering).
Sustainable Design (also referred to as "green design", "eco-design", or "design for environment") is the art of designing physical objects and the built environment to comply with the principles of sustainability. It ranges from the microcosm of designing small objects for everyday use, through to the macrocosm of designing buildings, cities, and the earth's physical surface.
Zero Net Energy Building is another popular term. It is for a building with zero net energy consumption and zero carbon emissions annually. However, many people have to live in zero-energy buildings e.g. hut, tent, cave, etc. out of necessity. Zero net energy buildings achieve one key Green Building goal of "reducing energy use and greenhouse gas emissions for the life of the building". Zero net energy buildings may or may not be considered "green" in all areas, such as reducing waste, using recycled building materials, etc. However, zero net energy buildings do tend to have a much lower ecological impact over the life of the building compared with 'Green Buildings' that require additional energy to be habitable and meet the needs of occupants. Natural Building, a similar concept, is usually on a smaller scale and tends to focus on the use of natural materials that are available locally.
How to Build a Green Building?Effective Green Buildings are more than just a random collection of environment-friendly material & technologies. They require careful, systemic attention to the full life cycle impacts of the resources embodied in the building and to reduce consumption and pollution emissions over the complete life cycle of the building. This is accomplished through an integrated approach to architecture, blending design issues, use of energy-efficient materials, construction techniques, effective building systems and taking advantage of renewable energy supplies. Maximum benefit is achieved by implementing these from an early stage of the project. Environment-friendly architecture is a process that must be integrated into every phase of the construction project from beginning to end. To achieve true environment-friendly architecture, eco-friendly ideas need to be supported by everyone involved in the process from design to construction.
All buildings have the potential to become a Green Building. New buildings can be constructed with green method and operated to be Green Building. Existing buildings can also become green through remodeling, retrofitting and improved operations.
Economic Impact of a Green BuildingInitially Green Building, when compared to conventional building, may seem expensive because the green building materials may cost more. However, actually there is money saved over its life because of lower operating and maintenance costs. These savings may be more apparent through life-cycle assessment (LCA). LCA is the science of measuring the environmental effects of a building "from cradle to grave," i.e. from extraction of the materials used to make the building to its ultimate disposal. The incremental initial cost for the first few Green Buildings in India can be found in the Table 2 (source Indian Green Building Council (IGBC)).
The declining incremental cost over the years is evident. Most Green Buildings may cost an extra of <2%, but are likely to yield up to 10 times as much over the entire life of the building. It means, integrating sustainable or "green" building practices into the construction of building is an investment. Resale values of Green Buildings are usually greater than the buildings which are conventionally built. When we consider the cost benefits of Green Building in terms of energy savings, worker productivity and safer indoor air quality for occupants, longevity of the building, environmental footprint, etc., then the initial expenses should not be a concern.
Also the integrated design processes towards Green Building can reduce even the initial costs. For example, in some cases, when buildings are carefully designed to be energy efficient, heating/ventilation/air conditioning equipment can be downsized for significant savings. There are also many locally available green products and materials that cost the same or even less than conventional ones.
Environment-friendly Green Building MaterialsTo determine whether a building is "green", we need to consider the building materials used, among other things. A Green Building shall use the products that are non-toxic, reusable, renewable and recyclable wherever possible. Green Building materials will have a lesser or reduced effect on human health and the environment when compared with competing products for the same purpose. It is generally agreed that using "Environment- friendly material" will
- Improve the health of the occupants
- Protect our natural ecosystems and resources
- Reduce energy consumption
Usage of high strength steel reduces the input quantity. Also if quality coated steel is used, there is no need for replacement for a long time. Thus, quantity reduction during life cycle also happens because of longer life from usage of quality coated steel. Recyclability and reusability properties can become vital factors, if the waste management and landfill of building wastes becomes a problem. In addition, steel building
- Reduces installation costs by increasing productivity (quicker with local labour) and using less energy and water,
- Does not have adverse environmental impacts as there is no disturbance to local flora
- Reduces the heat island effect because of lower thermal mass and good thermal reflecting properties of special coated steels