In view of the environmental quandaries that our planet currently suffers from that cause human beings, green buildings or sustainable buildings came as one of the reactions to solve these quandaries. With incremented cognizance and the exigent need to truncate environmental pollution, architects have increasingly relied on green building design. Green buildings take into account environmental considerations at every stage of the construction, such as design, implementation, operation, maintenance and major considerations, which in turn take into account energy and water efficiency, resource efficiency and the quality of the internal environment of the building. We will additionally not forget the impact of the building on the surrounding environment, as the distinction between subsisting buildings and green buildings is that the design of green buildings seeks to ameliorate the properties of environmental sustainability, amend performance, and preserve construction costs.
The standards adopted in the evaluation of green buildings
It is not facile to judge a building belonging to the green building sector, as it requires a team of specialists to assess the degree of sustainability of this building and this evaluation depends on global systems. These regulations determine the degree of effectiveness of any environmentally friendly building, as classification systems differ from one country to another and the most famous of these systems is LEED (Leadership in Energy and Environmental Design). Green buildings are classified according to LEED organization into three levels: gold, silver and platinum according to the degree of quality of application of the criteria required for sustainability.
As mentioned previously, these standards depend on the construction site, the surrounding environment, and energy efficiency, where the energy sources used are renewable and water-efficient as they work to reduce water waste and choose more water-saving products. In addition to the quality of the facility\'s internal environment, an example of this is the reduction of health problems due to insufficient air quality, poor ventilation, lighting and other problems that some traditional buildings suffer from, as green buildings find appropriate solutions to all these problems (Castro-Lacouture, A.Sefairb, Flórezb, & L.Medaglia, 2008).
The effect of green buildings on health
A lot of research has been done around the world and its results have shown that environmentally friendly buildings are much better for the health of the people who live and work in them and it influences the level of activity of the individual and the quality of his sleep (Durmus-Pedini & Ashuri, 2010) (Kats, 2003). Also, some studies conducted on more than 69,000 buildings, homes, offices, and factories show that there are fewer diseases among residents and workers who have gone through the experience of green buildings, due to the quality of the internal environment, where Dr Joseph Allen and health researchers environmental teammates at Harvard T.H. Chan school of public health in the United States study reports from around the world in the green buildings lent to human health.
It was found through studies that green building occupants are generally more satisfied with the place in terms of indoor air quality, workspace, and building cleanliness and maintenance, as Dr Allen says. The research also adds a measure of indoor air quality, ventilation, filtering, lighting and acoustics, and the results showed that in green residential buildings there were fewer children suffering from asthma problems and respiratory diseases. This gives a clear picture of the importance of green buildings and their positive impact on waking, which makes us support the idea of green buildings.
Green building properties and benefits
One of the most important factors in designing green buildings is energy efficiency, which has a major impact on reducing carbon emissions by 33% (Durmus-Pedini & Ashuri, 2010). These factors include careful selection of windows, good insulation to maintain air temperature, insulation of air conditioning pipes, use of smart lighting systems, use of renewable energy such as wind, solar and bioenergy. The figure below shows the idea of green buildings and the most important factors in their design.
Considering that green buildings do not understand the meaning of wasting something, they are designed to be able to recycle rainwater and greywater (less polluted water) for reuse again. It has been proven that green buildings consume 54% less water. Moreover, green buildings\' reliance mainly on renewable energy instead of non-renewable energy such as oil and gas saves energy use in these buildings by 45% less than traditional buildings (Durmus-Pedini & Ashuri, 2010).
The impact of obstacles and barriers on the use of green buildings
Despite the importance of relying on green buildings as a future trend in the urban sector, this trend suffers from several obstacles that are likely to affect the speed of the spread of such facilities. The first obstacle is the high construction costs. Although green buildings depend on their construction on local materials to avoid shipping costs and recycled materials used in construction, in the absence of these materials, construction costs will be high. A study (Zhang, Platten, & Shen, 2011) has found that this problem of high prices for materials and green technologies is one of the barriers in building sustainable buildings in China. Another obstacle is the lack of teams with the required expertise and skills. This lack of experience raises the costs of designing and planning. It also costs additional time and effort which is not preferred by investors.
In addition, investors are not the biggest beneficiaries of such projects but rather the ultimate owners. Therefore, the additional costs of green buildings that can be offset in the long run are not a catalyst for investors. Here, the economic situation of countries plays an important role. In poor countries where tax incentives and financial support plans are absent, it is more difficult to stimulate investments in the sustainable building sector (Cheun Chan, Darko, Olanipekun, & Ameyaw, 2017). Finally, the lack of information available in societies about green buildings prevents building good confidence in them. This will compel investors to resort to advertising campaigns in order to create with the buyer for real estate marketing. That is not preferred by the investor, who in general is not inclined to adventure, but he favours the traditional method of guaranteeing profits.
The future of green buildings
Green buildings represent an important measure to mitigate the negative impacts of construction on various environmental and economic aspects. Despite the great obstacles facing building sustainable facilities, research and figures indicate a prosperous future for such industries. One of the most important current incentives that have contributed to promoting the idea of green building is the tendency of the governments of industrialized countries to support such projects through tax cuts and easy loans. \nAs governments are fully aware that the financial returns from these projects, in the long run, exceed the facilities offered to investors. Nor is the economic catalyst alone that motivates governments to support them, but the moral obligation to create appropriate environmental conditions for the next generations. In scientific terms, a noticeable increase has been recorded in the number of studies concerned with green buildings. This will help to raise the technical capabilities and skills of workers in this sector.